Merge pull request #593 from hathach/edpt_ISO_xfer

Edpt iso xfer

6 files changed, 1566 insertions, 660 deletions

diff --git a/src/class/audio/audio.h b/src/class/audio/audio.h
index 05e61f8df..936f09104 100644
--- a/src/class/audio/audio.h
+++ b/src/class/audio/audio.h
@@ -469,44 +469,28 @@ typedef enum
 /// Additional Audio Device Class Codes - Source: Audio Data Formats
 
 /// A.1 - Audio Class-Format Type Codes UAC2
-//typedef enum
-//{
-//  AUDIO_FORMAT_TYPE_UNDEFINED     = 0x00,
-//  AUDIO_FORMAT_TYPE_I             = 0x01,
-//  AUDIO_FORMAT_TYPE_II            = 0x02,
-//  AUDIO_FORMAT_TYPE_III           = 0x03,
-//  AUDIO_FORMAT_TYPE_IV            = 0x04,
-//  AUDIO_EXT_FORMAT_TYPE_I         = 0x81,
-//  AUDIO_EXT_FORMAT_TYPE_II        = 0x82,
-//  AUDIO_EXT_FORMAT_TYPE_III       = 0x83,
-//} audio_format_type_t;
-
-#define AUDIO_FORMAT_TYPE_UNDEFINED     0x00
-#define AUDIO_FORMAT_TYPE_I             0x01
-#define AUDIO_FORMAT_TYPE_II            0x02
-#define AUDIO_FORMAT_TYPE_III           0x03
-#define AUDIO_FORMAT_TYPE_IV            0x04
-#define AUDIO_EXT_FORMAT_TYPE_I         0x81
-#define AUDIO_EXT_FORMAT_TYPE_II        0x82
-#define AUDIO_EXT_FORMAT_TYPE_III       0x83
-
-/// A.2.1 - Audio Class-Audio Data Format Type I UAC2
-//typedef enum
-//{
-//  AUDIO_DATA_FORMAT_TYPE_I_PCM            = (uint32_t) (1 << 0),
-//  AUDIO_DATA_FORMAT_TYPE_I_PCM8           = (uint32_t) (1 << 1),
-//  AUDIO_DATA_FORMAT_TYPE_I_IEEE_FLOAT     = (uint32_t) (1 << 2),
-//  AUDIO_DATA_FORMAT_TYPE_I_ALAW           = (uint32_t) (1 << 3),
-//  AUDIO_DATA_FORMAT_TYPE_I_MULAW          = (uint32_t) (1 << 4),
-//  AUDIO_DATA_FORMAT_TYPE_I_RAW_DATA       = 0x100000000,
-//} audio_data_format_type_I_t;
+typedef enum
+{
+  AUDIO_FORMAT_TYPE_UNDEFINED     = 0x00,
+  AUDIO_FORMAT_TYPE_I             = 0x01,
+  AUDIO_FORMAT_TYPE_II            = 0x02,
+  AUDIO_FORMAT_TYPE_III           = 0x03,
+  AUDIO_FORMAT_TYPE_IV            = 0x04,
+  AUDIO_EXT_FORMAT_TYPE_I         = 0x81,
+  AUDIO_EXT_FORMAT_TYPE_II        = 0x82,
+  AUDIO_EXT_FORMAT_TYPE_III       = 0x83,
+} audio_format_type_t;
 
-#define AUDIO_DATA_FORMAT_TYPE_I_PCM            ((uint32_t) (1 << 0))
-#define AUDIO_DATA_FORMAT_TYPE_I_PCM8           ((uint32_t) (1 << 1))
-#define AUDIO_DATA_FORMAT_TYPE_I_IEEE_FLOAT     ((uint32_t) (1 << 2))
-#define AUDIO_DATA_FORMAT_TYPE_I_ALAW           ((uint32_t) (1 << 3))
-#define AUDIO_DATA_FORMAT_TYPE_I_MULAW          ((uint32_t) (1 << 4))
-#define AUDIO_DATA_FORMAT_TYPE_I_RAW_DATA       0x100000000
+// A.2.1 - Audio Class-Audio Data Format Type I UAC2
+typedef enum
+{
+  AUDIO_DATA_FORMAT_TYPE_I_PCM            = (uint32_t) (1 << 0),
+  AUDIO_DATA_FORMAT_TYPE_I_PCM8           = (uint32_t) (1 << 1),
+  AUDIO_DATA_FORMAT_TYPE_I_IEEE_FLOAT     = (uint32_t) (1 << 2),
+  AUDIO_DATA_FORMAT_TYPE_I_ALAW           = (uint32_t) (1 << 3),
+  AUDIO_DATA_FORMAT_TYPE_I_MULAW          = (uint32_t) (1 << 4),
+  AUDIO_DATA_FORMAT_TYPE_I_RAW_DATA       = 0x100000000,
+} audio_data_format_type_I_t;
 
 /// All remaining definitions are taken from the descriptor descriptions in the UAC2 main specification
 
@@ -901,7 +885,7 @@ typedef struct TU_ATTR_PACKED {
     } subrange[numSubRanges]    ;               \
 }
 
-    /// 5.2.3.2 2-byte Control RANGE Parameter Block
+/// 5.2.3.2 2-byte Control RANGE Parameter Block
 #define audio_control_range_2_n_t(numSubRanges) \
     struct TU_ATTR_PACKED {                     \
   uint16_t wNumSubRanges;                       \
@@ -912,7 +896,7 @@ typedef struct TU_ATTR_PACKED {
     } subrange[numSubRanges];                   \
 }
 
-    // 5.2.3.3 4-byte Control RANGE Parameter Block
+// 5.2.3.3 4-byte Control RANGE Parameter Block
 #define audio_control_range_4_n_t(numSubRanges) \
     struct TU_ATTR_PACKED {                     \
   uint16_t wNumSubRanges;                       \
@@ -923,12 +907,12 @@ typedef struct TU_ATTR_PACKED {
     } subrange[numSubRanges];                   \
 }
 
-    /** @} */
+/** @} */
 
 #ifdef __cplusplus
-  }
+}
 #endif
 
 #endif
 
-  /** @} */
+/** @} */
diff --git a/src/class/audio/audio_device.c b/src/class/audio/audio_device.c
index 8581925e4..4057f5f64 100644
--- a/src/class/audio/audio_device.c
+++ b/src/class/audio/audio_device.c
@@ -30,6 +30,22 @@
  *
  * In case you need more alternate interfaces, you need to define additional defines for this specific alternate interface. Just define them and set them in the set_interface function.
  *
+ * There are three data flow structures currently implemented, where at least one SW-FIFO is used to decouple the asynchronous processes MCU vs. host
+ *
+ * 1. Input data -> SW-FIFO -> MCU USB
+ *
+ * The most easiest version, available in case the target MCU can handle the software FIFO (SW-FIFO) and if it is implemented in the device driver (if yes then dcd_edpt_xfer_fifo() is available)
+ *
+ * 2. Input data -> SW-FIFO -> Linear buffer -> MCU USB
+ *
+ * In case the target MCU can not handle a SW-FIFO, a linear buffer is used. This uses the default function dcd_edpt_xfer(). In this case more memory is required.
+ *
+ * 3. (Input data 1 | Input data 2 | ... | Input data N) ->  (SW-FIFO 1 | SW-FIFO 2 | ... | SW-FIFO N) -> Linear buffer -> MCU USB
+ *
+ * This case is used if you have more channels which need to be combined into one stream. Every channel has its own SW-FIFO. All data is encoded into an Linear buffer.
+ *
+ * The same holds in the RX case.
+ *
  * */
 
 #include "tusb_option.h"
@@ -47,15 +63,179 @@
 // MACRO CONSTANT TYPEDEF
 //--------------------------------------------------------------------+
 
-#if CFG_TUD_AUDIO_EPSIZE_IN && CFG_TUD_AUDIO_TX_FIFO_SIZE
-#ifndef CFG_TUD_AUDIO_TX_FIFO_COUNT
-#define CFG_TUD_AUDIO_TX_FIFO_COUNT CFG_TUD_AUDIO_N_CHANNELS_TX
+// Linear buffer in case target MCU is not capable of handling a ring buffer FIFO e.g. no hardware buffer
+// is available or driver is would need to be changed dramatically
+
+// Only STM32 synopsys use non-linear buffer for now
+// Synopsys detection copied from dcd_synopsys.c (refactor later on)
+#if defined (STM32F105x8) || defined (STM32F105xB) || defined (STM32F105xC) || \
+    defined (STM32F107xB) || defined (STM32F107xC)
+#define STM32F1_SYNOPSYS
+#endif
+
+#if defined (STM32L475xx) || defined (STM32L476xx) ||                          \
+    defined (STM32L485xx) || defined (STM32L486xx) || defined (STM32L496xx) || \
+    defined (STM32L4R5xx) || defined (STM32L4R7xx) || defined (STM32L4R9xx) || \
+    defined (STM32L4S5xx) || defined (STM32L4S7xx) || defined (STM32L4S9xx)
+#define STM32L4_SYNOPSYS
+#endif
+
+#if (CFG_TUSB_MCU == OPT_MCU_STM32F1 && defined(STM32F1_SYNOPSYS)) || \
+    CFG_TUSB_MCU == OPT_MCU_STM32F2                               || \
+    CFG_TUSB_MCU == OPT_MCU_STM32F4                               || \
+    CFG_TUSB_MCU == OPT_MCU_STM32F7                               || \
+    CFG_TUSB_MCU == OPT_MCU_STM32H7                               || \
+    (CFG_TUSB_MCU == OPT_MCU_STM32L4 && defined(STM32L4_SYNOPSYS))
+#define  USE_LINEAR_BUFFER     0
+#else
+#define  USE_LINEAR_BUFFER     1
 #endif
+
+// Declaration of buffers
+
+// Check for maximum supported numbers
+#if CFG_TUD_AUDIO > 3
+#error Maximum number of audio functions restricted to three!
 #endif
 
-#if CFG_TUD_AUDIO_EPSIZE_OUT && CFG_TUD_AUDIO_RX_FIFO_SIZE
-#ifndef CFG_TUD_AUDIO_RX_FIFO_COUNT
-#define CFG_TUD_AUDIO_RX_FIFO_COUNT CFG_TUD_AUDIO_N_CHANNELS_RX
+// EP IN software buffers and mutexes
+#if CFG_TUD_AUDIO_ENABLE_EP_IN && !CFG_TUD_AUDIO_ENABLE_ENCODING
+#if CFG_TUD_AUDIO_FUNC_1_EP_IN_SW_BUF_SZ > 0
+CFG_TUSB_MEM_ALIGN uint8_t audio_ep_in_sw_buf_1[CFG_TUD_AUDIO_FUNC_1_EP_IN_SW_BUF_SZ];
+#if CFG_FIFO_MUTEX
+osal_mutex_def_t ep_in_ff_mutex_wr_1;                                                             // No need for read mutex as only USB driver reads from FIFO
+#endif
+#endif // CFG_TUD_AUDIO_FUNC_1_EP_IN_SW_BUF_SZ > 0
+#if CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_EP_IN_SW_BUF_SZ > 0
+CFG_TUSB_MEM_ALIGN uint8_t audio_ep_in_sw_buf_2[CFG_TUD_AUDIO_FUNC_2_EP_IN_SW_BUF_SZ];
+#if CFG_FIFO_MUTEX
+osal_mutex_def_t ep_in_ff_mutex_wr_2;                                                             // No need for read mutex as only USB driver reads from FIFO
+#endif
+#endif // CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_EP_IN_SW_BUF_SZ > 0
+#if CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_EP_IN_SW_BUF_SZ > 0
+CFG_TUSB_MEM_ALIGN uint8_t audio_ep_in_sw_buf_3[CFG_TUD_AUDIO_FUNC_3_EP_IN_SW_BUF_SZ];
+#if CFG_FIFO_MUTEX
+osal_mutex_def_t ep_in_ff_mutex_wr_3;                                                             // No need for read mutex as only USB driver reads from FIFO
+#endif
+#endif // CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_EP_IN_SW_BUF_SZ > 0
+#endif // CFG_TUD_AUDIO_ENABLE_EP_IN && !CFG_TUD_AUDIO_ENABLE_ENCODING
+
+// Linear buffer TX in case:
+// - target MCU is not capable of handling a ring buffer FIFO e.g. no hardware buffer is available or driver is would need to be changed dramatically OR
+// - the software encoding is used - in this case the linear buffers serve as a target memory where logical channels are encoded into
+#if CFG_TUD_AUDIO_ENABLE_EP_IN && (USE_LINEAR_BUFFER || CFG_TUD_AUDIO_ENABLE_ENCODING)
+#if CFG_TUD_AUDIO_FUNC_1_EP_IN_SZ_MAX > 0
+CFG_TUSB_MEM_ALIGN uint8_t lin_buf_in_1[CFG_TUD_AUDIO_FUNC_1_EP_IN_SZ_MAX];
+#endif
+#if CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_EP_IN_SZ_MAX > 0
+CFG_TUSB_MEM_ALIGN uint8_t lin_buf_in_2[CFG_TUD_AUDIO_FUNC_2_EP_IN_SZ_MAX];
+#endif
+#if CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_EP_IN_SZ_MAX > 0
+CFG_TUSB_MEM_ALIGN uint8_t lin_buf_in_3[CFG_TUD_AUDIO_FUNC_3_EP_IN_SZ_MAX];
+#endif
+#endif // CFG_TUD_AUDIO_ENABLE_EP_IN && (USE_LINEAR_BUFFER || CFG_TUD_AUDIO_ENABLE_DECODING)
+
+// EP OUT software buffers and mutexes
+#if CFG_TUD_AUDIO_ENABLE_EP_OUT && !CFG_TUD_AUDIO_ENABLE_DECODING
+#if CFG_TUD_AUDIO_FUNC_1_EP_OUT_SW_BUF_SZ > 0
+CFG_TUSB_MEM_ALIGN uint8_t audio_ep_out_sw_buf_1[CFG_TUD_AUDIO_FUNC_1_EP_OUT_SW_BUF_SZ];
+#if CFG_FIFO_MUTEX
+osal_mutex_def_t ep_out_ff_mutex_rd_1;                                                            // No need for write mutex as only USB driver writes into FIFO
+#endif
+#endif // CFG_TUD_AUDIO_FUNC_1_EP_OUT_SW_BUF_SZ > 0
+#if CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_EP_OUT_SW_BUF_SZ > 0
+CFG_TUSB_MEM_ALIGN uint8_t audio_ep_out_sw_buf_2[CFG_TUD_AUDIO_FUNC_2_EP_OUT_SW_BUF_SZ];
+#if CFG_FIFO_MUTEX
+osal_mutex_def_t ep_out_ff_mutex_rd_2;                                                            // No need for write mutex as only USB driver writes into FIFO
+#endif
+#endif // CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_EP_OUT_SW_BUF_SZ > 0
+#if CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_EP_OUT_SW_BUF_SZ > 0
+CFG_TUSB_MEM_ALIGN uint8_t audio_ep_out_sw_buf_3[CFG_TUD_AUDIO_FUNC_3_EP_OUT_SW_BUF_SZ];
+#if CFG_FIFO_MUTEX
+osal_mutex_def_t ep_out_ff_mutex_rd_3;                                                            // No need for write mutex as only USB driver writes into FIFO
+#endif
+#endif // CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_EP_OUT_SW_BUF_SZ > 0
+#endif // CFG_TUD_AUDIO_ENABLE_EP_OUT && !CFG_TUD_AUDIO_ENABLE_DECODING
+
+// Linear buffer RX in case:
+// - target MCU is not capable of handling a ring buffer FIFO e.g. no hardware buffer is available or driver is would need to be changed dramatically OR
+// - the software encoding is used - in this case the linear buffers serve as a target memory where logical channels are encoded into
+#if CFG_TUD_AUDIO_ENABLE_EP_OUT && (USE_LINEAR_BUFFER || CFG_TUD_AUDIO_ENABLE_DECODING)
+#if CFG_TUD_AUDIO_FUNC_1_EP_OUT_SZ_MAX > 0
+CFG_TUSB_MEM_ALIGN uint8_t lin_buf_out_1[CFG_TUD_AUDIO_FUNC_1_EP_OUT_SZ_MAX];
+#endif
+#if CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_EP_OUT_SZ_MAX > 0
+CFG_TUSB_MEM_ALIGN uint8_t lin_buf_out_2[CFG_TUD_AUDIO_FUNC_2_EP_OUT_SZ_MAX];
+#endif
+#if CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_EP_OUT_SZ_MAX > 0
+CFG_TUSB_MEM_ALIGN uint8_t lin_buf_out_3[CFG_TUD_AUDIO_FUNC_3_EP_OUT_SZ_MAX];
+#endif
+#endif // CFG_TUD_AUDIO_ENABLE_EP_OUT && (USE_LINEAR_BUFFER || CFG_TUD_AUDIO_ENABLE_DECODING)
+
+// Control buffers
+CFG_TUSB_MEM_ALIGN uint8_t ctrl_buf_1[CFG_TUD_AUDIO_FUNC_1_CTRL_BUF_SZ];
+#if CFG_TUD_AUDIO > 1
+CFG_TUSB_MEM_ALIGN uint8_t ctrl_buf_2[CFG_TUD_AUDIO_FUNC_2_CTRL_BUF_SZ];
+#endif
+#if CFG_TUD_AUDIO > 2
+CFG_TUSB_MEM_ALIGN uint8_t ctrl_buf_3[CFG_TUD_AUDIO_FUNC_3_CTRL_BUF_SZ];
+#endif
+
+// Active alternate setting of interfaces
+CFG_TUSB_MEM_ALIGN uint8_t alt_setting_1[CFG_TUD_AUDIO_FUNC_1_N_AS_INT];
+#if CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_N_AS_INT > 0
+CFG_TUSB_MEM_ALIGN uint8_t alt_setting_2[CFG_TUD_AUDIO_FUNC_2_N_AS_INT];
+#endif
+#if CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_N_AS_INT > 0
+CFG_TUSB_MEM_ALIGN uint8_t alt_setting_3[CFG_TUD_AUDIO_FUNC_3_N_AS_INT];
+#endif
+
+// Software encoding/decoding support FIFOs
+#if CFG_TUD_AUDIO_ENABLE_EP_IN && CFG_TUD_AUDIO_ENABLE_ENCODING
+#if CFG_TUD_AUDIO_FUNC_1_TX_SUPP_SW_FIFO_SZ > 0
+CFG_TUSB_MEM_ALIGN uint8_t tx_supp_ff_buf_1[CFG_TUD_AUDIO_FUNC_1_N_TX_SUPP_SW_FIFO][CFG_TUD_AUDIO_FUNC_1_TX_SUPP_SW_FIFO_SZ];
+tu_fifo_t tx_supp_ff_1[CFG_TUD_AUDIO_FUNC_1_N_TX_SUPP_SW_FIFO];
+#if CFG_FIFO_MUTEX
+osal_mutex_def_t tx_supp_ff_mutex_wr_1[CFG_TUD_AUDIO_FUNC_1_N_TX_SUPP_SW_FIFO];                   // No need for read mutex as only USB driver reads from FIFO
+#endif
+#endif
+#if CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_TX_SUPP_SW_FIFO_SZ > 0
+CFG_TUSB_MEM_ALIGN uint8_t tx_supp_ff_buf_2[CFG_TUD_AUDIO_FUNC_2_N_TX_SUPP_SW_FIFO][CFG_TUD_AUDIO_FUNC_2_TX_SUPP_SW_FIFO_SZ];
+tu_fifo_t tx_supp_ff_2[CFG_TUD_AUDIO_FUNC_2_N_TX_SUPP_SW_FIFO];
+#if CFG_FIFO_MUTEX
+osal_mutex_def_t tx_supp_ff_mutex_wr_2[CFG_TUD_AUDIO_FUNC_2_N_TX_SUPP_SW_FIFO];                   // No need for read mutex as only USB driver reads from FIFO
+#endif
+#endif
+#if CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_TX_SUPP_SW_FIFO_SZ > 0
+CFG_TUSB_MEM_ALIGN uint8_t tx_supp_ff_buf_3[CFG_TUD_AUDIO_FUNC_3_N_TX_SUPP_SW_FIFO][CFG_TUD_AUDIO_FUNC_3_TX_SUPP_SW_FIFO_SZ];
+tu_fifo_t tx_supp_ff_3[CFG_TUD_AUDIO_FUNC_3_N_TX_SUPP_SW_FIFO];
+#if CFG_FIFO_MUTEX
+osal_mutex_def_t tx_supp_ff_mutex_wr_3[CFG_TUD_AUDIO_FUNC_3_N_TX_SUPP_SW_FIFO];                   // No need for read mutex as only USB driver reads from FIFO
+#endif
+#endif
+#endif
+
+#if CFG_TUD_AUDIO_ENABLE_EP_OUT && CFG_TUD_AUDIO_ENABLE_DECODING
+#if CFG_TUD_AUDIO_FUNC_1_RX_SUPP_SW_FIFO_SZ > 0
+CFG_TUSB_MEM_ALIGN uint8_t rx_supp_ff_buf_1[CFG_TUD_AUDIO_FUNC_1_N_RX_SUPP_SW_FIFO][CFG_TUD_AUDIO_FUNC_1_RX_SUPP_SW_FIFO_SZ];
+tu_fifo_t rx_supp_ff_1[CFG_TUD_AUDIO_FUNC_1_N_RX_SUPP_SW_FIFO];
+#if CFG_FIFO_MUTEX
+osal_mutex_def_t rx_supp_ff_mutex_rd_1[CFG_TUD_AUDIO_FUNC_1_N_RX_SUPP_SW_FIFO];                   // No need for write mutex as only USB driver writes into FIFO
+#endif
+#endif
+#if CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_RX_SUPP_SW_FIFO_SZ > 0
+CFG_TUSB_MEM_ALIGN uint8_t rx_supp_ff_buf_2[CFG_TUD_AUDIO_FUNC_2_N_RX_SUPP_SW_FIFO][CFG_TUD_AUDIO_FUNC_2_RX_SUPP_SW_FIFO_SZ];
+tu_fifo_t rx_supp_ff_2[CFG_TUD_AUDIO_FUNC_2_N_RX_SUPP_SW_FIFO];
+#if CFG_FIFO_MUTEX
+osal_mutex_def_t rx_supp_ff_mutex_rd_2[CFG_TUD_AUDIO_FUNC_2_N_RX_SUPP_SW_FIFO];                   // No need for write mutex as only USB driver writes into FIFO
+#endif
+#endif
+#if CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_RX_SUPP_SW_FIFO_SZ > 0
+CFG_TUSB_MEM_ALIGN uint8_t rx_supp_ff_buf_3[CFG_TUD_AUDIO_FUNC_3_N_RX_SUPP_SW_FIFO][CFG_TUD_AUDIO_FUNC_3_RX_SUPP_SW_FIFO_SZ];
+tu_fifo_t rx_supp_ff_3[CFG_TUD_AUDIO_FUNC_3_N_RX_SUPP_SW_FIFO];
+#if CFG_FIFO_MUTEX
+osal_mutex_def_t rx_supp_ff_mutex_rd_3[CFG_TUD_AUDIO_FUNC_3_N_RX_SUPP_SW_FIFO];                   // No need for write mutex as only USB driver writes into FIFO
+#endif
 #endif
 #endif
 
@@ -64,14 +244,15 @@ typedef struct
   uint8_t rhport;
   uint8_t const * p_desc;       // Pointer pointing to Standard AC Interface Descriptor(4.7.1) - Audio Control descriptor defining audio function
 
-#if CFG_TUD_AUDIO_EPSIZE_IN
-  uint8_t ep_in;                // Outgoing (out of uC) audio data EP.
-  uint16_t epin_buf_cnt;        // Count filling status of EP in buffer - this is a shared state currently and is intended to be removed once EP buffers can be implemented as FIFOs!
+#if CFG_TUD_AUDIO_ENABLE_EP_IN
+  uint8_t ep_in;                // TX audio data EP.
+  uint16_t ep_in_sz;            // Current size of TX EP
   uint8_t ep_in_as_intf_num;    // Corresponding Standard AS Interface Descriptor (4.9.1) belonging to output terminal to which this EP belongs - 0 is invalid (this fits to UAC2 specification since AS interfaces can not have interface number equal to zero)
 #endif
 
-#if CFG_TUD_AUDIO_EPSIZE_OUT
+#if CFG_TUD_AUDIO_ENABLE_EP_OUT
   uint8_t ep_out;               // Incoming (into uC) audio data EP.
+  uint16_t ep_out_sz;           // Current size of RX EP
   uint8_t ep_out_as_intf_num;   // Corresponding Standard AS Interface Descriptor (4.9.1) belonging to input terminal to which this EP belongs - 0 is invalid (this fits to UAC2 specification since AS interfaces can not have interface number equal to zero)
 
 #if CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP
@@ -84,59 +265,98 @@ typedef struct
   uint8_t ep_int_ctr;           // Audio control interrupt EP.
 #endif
 
-#if CFG_TUD_AUDIO_N_AS_INT
-  uint8_t altSetting[CFG_TUD_AUDIO_N_AS_INT];   // We need to save the current alternate setting this way, because it is possible that there are AS interfaces which do not have an EP!
-#endif
+  uint8_t * alt_setting;   // We need to save the current alternate setting this way, because it is possible that there are AS interfaces which do not have an EP!
+
   /*------------- From this point, data is not cleared by bus reset -------------*/
 
+  //
+  uint16_t desc_length;         // Length of audio function descriptor
+
   // Buffer for control requests
-  CFG_TUSB_MEM_ALIGN uint8_t ctrl_buf[CFG_TUD_AUDIO_CTRL_BUF_SIZE];
+  uint8_t * ctrl_buf;
+  uint8_t ctrl_buf_sz;
 
-  // FIFO
-#if CFG_TUD_AUDIO_EPSIZE_IN && CFG_TUD_AUDIO_TX_FIFO_SIZE
-  tu_fifo_t tx_ff[CFG_TUD_AUDIO_TX_FIFO_COUNT];
-  CFG_TUSB_MEM_ALIGN uint8_t tx_ff_buf[CFG_TUD_AUDIO_TX_FIFO_COUNT][CFG_TUD_AUDIO_TX_FIFO_SIZE];
-#if CFG_FIFO_MUTEX
-  osal_mutex_def_t tx_ff_mutex[CFG_TUD_AUDIO_TX_FIFO_COUNT];
-#endif
+  // EP Transfer buffers and FIFOs
+#if CFG_TUD_AUDIO_ENABLE_EP_OUT
+#if !CFG_TUD_AUDIO_ENABLE_DECODING
+  tu_fifo_t ep_out_ff;
 #endif
 
-#if CFG_TUD_AUDIO_EPSIZE_OUT && CFG_TUD_AUDIO_RX_FIFO_SIZE
-  tu_fifo_t rx_ff[CFG_TUD_AUDIO_RX_FIFO_COUNT];
-  CFG_TUSB_MEM_ALIGN uint8_t rx_ff_buf[CFG_TUD_AUDIO_RX_FIFO_COUNT][CFG_TUD_AUDIO_RX_FIFO_SIZE];
-#if CFG_FIFO_MUTEX
-  osal_mutex_def_t rx_ff_mutex[CFG_TUD_AUDIO_RX_FIFO_COUNT];
+#if CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP
+  uint32_t fb_val;                                                              // Feedback value for asynchronous mode (in 16.16 format).
+#endif
 #endif
+
+#if CFG_TUD_AUDIO_ENABLE_EP_IN && !CFG_TUD_AUDIO_ENABLE_ENCODING
+  tu_fifo_t ep_in_ff;
 #endif
 
+  // Audio control interrupt buffer - no FIFO - 6 Bytes according to UAC 2 specification (p. 74)
 #if CFG_TUD_AUDIO_INT_CTR_EPSIZE_IN
-  tu_fifo_t int_ctr_ff;
-  CFG_TUSB_MEM_ALIGN uint8_t int_ctr_ff_buf[CFG_TUD_AUDIO_INT_CTR_BUFSIZE];
-#if CFG_FIFO_MUTEX
-  osal_mutex_def_t int_ctr_ff_mutex;
+  CFG_TUSB_MEM_ALIGN uint8_t ep_int_ctr_buf[CFG_TUD_AUDIO_INT_CTR_EP_IN_SW_BUFFER_SIZE];
+#endif
+
+  // Decoding parameters - parameters are set when alternate AS interface is set by host
+  // Coding is currently only supported for EP. Software coding corresponding to AS interfaces without EPs are not supported currently.
+#if CFG_TUD_AUDIO_ENABLE_EP_OUT && CFG_TUD_AUDIO_ENABLE_DECODING
+  audio_format_type_t format_type_rx;
+  uint8_t n_channels_rx;
+
+#if CFG_TUD_AUDIO_ENABLE_TYPE_I_DECODING
+  audio_data_format_type_I_t format_type_I_rx;
+  uint8_t n_bytes_per_sampe_rx;
+  uint8_t n_channels_per_ff_rx;
+  uint8_t n_ff_used_rx;
 #endif
 #endif
 
-  // Endpoint Transfer buffers
-#if CFG_TUD_AUDIO_EPSIZE_OUT
-  CFG_TUSB_MEM_ALIGN uint8_t epout_buf[CFG_TUD_AUDIO_EPSIZE_OUT];        // Bigger makes no sense for isochronous EP's (but technically possible here)
+  // Encoding parameters - parameters are set when alternate AS interface is set by host
+#if CFG_TUD_AUDIO_ENABLE_EP_IN && CFG_TUD_AUDIO_ENABLE_ENCODING
+  audio_format_type_t format_type_tx;
+  uint8_t n_channels_tx;
 
-#if CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP
-  uint32_t fb_val;                                                       // Feedback value for asynchronous mode (in 16.16 format).
+#if CFG_TUD_AUDIO_ENABLE_TYPE_I_ENCODING
+  audio_data_format_type_I_t format_type_I_tx;
+  uint8_t n_bytes_per_sampe_tx;
+  uint8_t n_channels_per_ff_tx;
+  uint8_t n_ff_used_tx;
+#endif
 #endif
 
+  // Support FIFOs for software encoding and decoding
+#if CFG_TUD_AUDIO_ENABLE_EP_OUT && CFG_TUD_AUDIO_ENABLE_DECODING
+  tu_fifo_t * rx_supp_ff;
+  uint8_t n_rx_supp_ff;
+  uint16_t rx_supp_ff_sz_max;
 #endif
 
-#if CFG_TUD_AUDIO_EPSIZE_IN
-  CFG_TUSB_MEM_ALIGN uint8_t epin_buf[CFG_TUD_AUDIO_EPSIZE_IN];         // Bigger makes no sense for isochronous EP's (but technically possible here)
+#if CFG_TUD_AUDIO_ENABLE_EP_IN && CFG_TUD_AUDIO_ENABLE_ENCODING
+  tu_fifo_t * tx_supp_ff;
+  uint8_t n_tx_supp_ff;
+  uint16_t tx_supp_ff_sz_max;
 #endif
 
-#if CFG_TUD_AUDIO_INT_CTR_EPSIZE_IN
-  CFG_TUSB_MEM_ALIGN uint8_t ep_int_ctr_buf[CFG_TUD_AUDIO_INT_CTR_EPSIZE_IN];
+  // Linear buffer in case target MCU is not capable of handling a ring buffer FIFO e.g. no hardware buffer is available or driver is would need to be changed dramatically OR the support FIFOs are used
+#if CFG_TUD_AUDIO_ENABLE_EP_OUT && (USE_LINEAR_BUFFER || CFG_TUD_AUDIO_ENABLE_DECODING)
+  uint8_t * lin_buf_out;
+#define USE_LINEAR_BUFFER_RX   1
+#endif
+
+#if CFG_TUD_AUDIO_ENABLE_EP_IN && (USE_LINEAR_BUFFER || CFG_TUD_AUDIO_ENABLE_ENCODING)
+  uint8_t * lin_buf_in;
+#define USE_LINEAR_BUFFER_TX   1
 #endif
 
 } audiod_interface_t;
 
+#ifndef USE_LINEAR_BUFFER_TX
+#define USE_LINEAR_BUFFER_TX   0
+#endif
+
+#ifndef USE_LINEAR_BUFFER_RX
+#define USE_LINEAR_BUFFER_RX   0
+#endif
+
 #define ITF_MEM_RESET_SIZE   offsetof(audiod_interface_t, ctrl_buf)
 
 //--------------------------------------------------------------------+
@@ -144,14 +364,20 @@ typedef struct
 //--------------------------------------------------------------------+
 CFG_TUSB_MEM_SECTION audiod_interface_t _audiod_itf[CFG_TUD_AUDIO];
 
-extern const uint16_t tud_audio_desc_lengths[];
+#if CFG_TUD_AUDIO_ENABLE_EP_OUT
+static bool audiod_rx_done_cb(uint8_t rhport, audiod_interface_t* audio, uint16_t n_bytes_received);
+#endif
+
+#if CFG_TUD_AUDIO_ENABLE_DECODING && CFG_TUD_AUDIO_ENABLE_EP_OUT
+static bool audiod_decode_type_I_pcm(uint8_t rhport, audiod_interface_t* audio, uint16_t n_bytes_received);
+#endif
 
-#if CFG_TUD_AUDIO_EPSIZE_OUT
-static bool audio_rx_done_type_I_pcm_ff_cb(uint8_t rhport, audiod_interface_t* audio, uint8_t * buffer, uint16_t bufsize);
+#if CFG_TUD_AUDIO_ENABLE_EP_IN
+static bool audiod_tx_done_cb(uint8_t rhport, audiod_interface_t* audio);
 #endif
 
-#if CFG_TUD_AUDIO_EPSIZE_IN
-static bool audiod_tx_done_type_I_pcm_ff_cb(uint8_t rhport, audiod_interface_t* audio);
+#if CFG_TUD_AUDIO_ENABLE_ENCODING && CFG_TUD_AUDIO_ENABLE_EP_IN
+static uint16_t audiod_encode_type_I_pcm(uint8_t rhport, audiod_interface_t* audio);
 #endif
 
 static bool audiod_get_interface(uint8_t rhport, tusb_control_request_t const * p_request);
@@ -162,36 +388,34 @@ static bool audiod_verify_entity_exists(uint8_t itf, uint8_t entityID, uint8_t *
 static bool audiod_verify_itf_exists(uint8_t itf, uint8_t *idxDriver);
 static bool audiod_verify_ep_exists(uint8_t ep, uint8_t *idxDriver);
 
+#if CFG_TUD_AUDIO_ENABLE_ENCODING || CFG_TUD_AUDIO_ENABLE_DECODING
+static void audiod_parse_for_AS_params(audiod_interface_t* audio, uint8_t const * p_desc, uint8_t const * p_desc_end, uint8_t const itf);
+#endif
+
+static inline uint8_t tu_desc_subtype(void const* desc)
+{
+  return ((uint8_t const*) desc)[2];
+}
+
 bool tud_audio_n_mounted(uint8_t itf)
 {
+  TU_VERIFY(itf < CFG_TUD_AUDIO);
   audiod_interface_t* audio = &_audiod_itf[itf];
 
-#if CFG_TUD_AUDIO_EPSIZE_OUT
-  if (audio->ep_out == 0)
-  {
-    return false;
-  }
+#if CFG_TUD_AUDIO_ENABLE_EP_OUT
+  if (audio->ep_out == 0) return false;
 #endif
 
-#if CFG_TUD_AUDIO_EPSIZE_IN
-  if (audio->ep_in == 0)
-  {
-    return false;
-  }
+#if CFG_TUD_AUDIO_ENABLE_EP_IN
+  if (audio->ep_in == 0) return false;
 #endif
 
 #if CFG_TUD_AUDIO_INT_CTR_EPSIZE_IN
-  if (audio->ep_int_ctr == 0)
-  {
-    return false;
-  }
+  if (audio->ep_int_ctr == 0) return false;
 #endif
 
 #if CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP
-  if (audio->ep_fb == 0)
-  {
-    return false;
-  }
+  if (audio->ep_fb == 0) return false;
 #endif
 
   return true;
@@ -201,70 +425,68 @@ bool tud_audio_n_mounted(uint8_t itf)
 // READ API
 //--------------------------------------------------------------------+
 
-#if CFG_TUD_AUDIO_EPSIZE_OUT && CFG_TUD_AUDIO_RX_FIFO_SIZE
-#if CFG_TUD_AUDIO_RX_FIFO_COUNT > 1
-uint16_t tud_audio_n_available(uint8_t itf, uint8_t channelId)
-{
-  TU_VERIFY(channelId < CFG_TUD_AUDIO_N_CHANNELS_RX);
-  return tu_fifo_count(&_audiod_itf[itf].rx_ff[channelId]);
-}
+#if CFG_TUD_AUDIO_ENABLE_EP_OUT && !CFG_TUD_AUDIO_ENABLE_DECODING
 
-uint16_t tud_audio_n_read(uint8_t itf, uint8_t channelId, void* buffer, uint16_t bufsize)
-{
-  TU_VERIFY(channelId < CFG_TUD_AUDIO_N_CHANNELS_RX);
-  return tu_fifo_read_n(&_audiod_itf[itf].rx_ff[channelId], buffer, bufsize);
-}
-
-void tud_audio_n_read_flush (uint8_t itf, uint8_t channelId)
-{
-  TU_VERIFY(channelId < CFG_TUD_AUDIO_N_CHANNELS_RX, );
-  tu_fifo_clear(&_audiod_itf[itf].rx_ff[channelId]);
-}
-#else
 uint16_t tud_audio_n_available(uint8_t itf)
 {
-  return tu_fifo_count(&_audiod_itf[itf].rx_ff[0]);
+  TU_VERIFY(itf < CFG_TUD_AUDIO && _audiod_itf[itf].p_desc != NULL);
+  return tu_fifo_count(&_audiod_itf[itf].ep_out_ff);
 }
 
 uint16_t tud_audio_n_read(uint8_t itf, void* buffer, uint16_t bufsize)
 {
-  return tu_fifo_read_n(&_audiod_itf[itf].rx_ff[0], buffer, bufsize);
+  TU_VERIFY(itf < CFG_TUD_AUDIO && _audiod_itf[itf].p_desc != NULL);
+  return tu_fifo_read_n(&_audiod_itf[itf].ep_out_ff, buffer, bufsize);
 }
 
-void tud_audio_n_read_flush (uint8_t itf)
+bool tud_audio_n_clear_ep_out_ff(uint8_t itf)
 {
-  tu_fifo_clear(&_audiod_itf[itf].rx_ff[0]);
+  TU_VERIFY(itf < CFG_TUD_AUDIO && _audiod_itf[itf].p_desc != NULL);
+  return tu_fifo_clear(&_audiod_itf[itf].ep_out_ff);
 }
-#endif
-#endif
 
-#if CFG_TUD_AUDIO_INT_CTR_EPSIZE_IN
+#endif
 
-uint16_t tud_audio_int_ctr_n_available(uint8_t itf)
+#if CFG_TUD_AUDIO_ENABLE_DECODING && CFG_TUD_AUDIO_ENABLE_EP_OUT
+// Delete all content in the support RX FIFOs
+bool tud_audio_n_clear_rx_support_ff(uint8_t itf, uint8_t channelId)
 {
-  return tu_fifo_count(&_audiod_itf[itf].int_ctr_ff);
+  TU_VERIFY(itf < CFG_TUD_AUDIO && _audiod_itf[itf].p_desc != NULL, channelId < _audiod_itf[itf].n_rx_supp_ff);
+  return tu_fifo_clear(&_audiod_itf[itf].rx_supp_ff[channelId]);
 }
 
-uint16_t tud_audio_int_ctr_n_read(uint8_t itf, void* buffer, uint16_t bufsize)
+uint16_t tud_audio_n_available_support_ff(uint8_t itf, uint8_t channelId)
 {
-  return tu_fifo_read_n(&_audiod_itf[itf].int_ctr_ff, buffer, bufsize);
+  TU_VERIFY(itf < CFG_TUD_AUDIO && _audiod_itf[itf].p_desc != NULL, channelId < _audiod_itf[itf].n_rx_supp_ff);
+  return tu_fifo_count(&_audiod_itf[itf].rx_supp_ff[channelId]);
 }
 
-void tud_audio_int_ctr_n_read_flush (uint8_t itf)
+uint16_t tud_audio_n_read_support_ff(uint8_t itf, uint8_t channelId, void* buffer, uint16_t bufsize)
 {
-  tu_fifo_clear(&_audiod_itf[itf].int_ctr_ff);
+  TU_VERIFY(itf < CFG_TUD_AUDIO && _audiod_itf[itf].p_desc != NULL, channelId < _audiod_itf[itf].n_rx_supp_ff);
+  return tu_fifo_read_n(&_audiod_itf[itf].rx_supp_ff[channelId], buffer, bufsize);
 }
-
 #endif
 
-// This function is called once something is received by USB and is responsible for decoding received stream into audio channels.
-// If you prefer your own (more efficient) implementation suiting your purpose set CFG_TUD_AUDIO_RX_FIFO_SIZE = 0.
+// This function is called once an audio packet is received by the USB and is responsible for putting data from USB memory into EP_OUT_FIFO (or support FIFOs + decoding of received stream into audio channels).
+// If you prefer your own (more efficient) implementation suiting your purpose set CFG_TUD_AUDIO_ENABLE_DECODING = 0.
 
-#if CFG_TUD_AUDIO_EPSIZE_OUT
+#if CFG_TUD_AUDIO_ENABLE_EP_OUT
 
-static bool audio_rx_done_cb(uint8_t rhport, audiod_interface_t* audio, uint8_t* buffer, uint16_t bufsize)
+static bool audiod_rx_done_cb(uint8_t rhport, audiod_interface_t* audio, uint16_t n_bytes_received)
 {
-  switch (CFG_TUD_AUDIO_FORMAT_TYPE_RX)
+  uint8_t idxDriver, idxItf;
+  uint8_t const *dummy2;
+
+  // Find index of audio streaming interface and index of interface
+  TU_VERIFY(audiod_get_AS_interface_index(audio->ep_out_as_intf_num, &idxDriver, &idxItf, &dummy2));
+
+  // Call a weak callback here - a possibility for user to get informed an audio packet was received and data gets now loaded into EP FIFO (or decoded into support RX software FIFO)
+  if (tud_audio_rx_done_pre_read_cb) TU_VERIFY(tud_audio_rx_done_pre_read_cb(rhport, n_bytes_received, idxDriver, audio->ep_out, audio->alt_setting[idxItf]));
+
+#if CFG_TUD_AUDIO_ENABLE_DECODING && CFG_TUD_AUDIO_ENABLE_EP_OUT
+
+  switch (audio->format_type_rx)
   {
     case AUDIO_FORMAT_TYPE_UNDEFINED:
       // INDIVIDUAL DECODING PROCEDURE REQUIRED HERE!
@@ -274,15 +496,10 @@ static bool audio_rx_done_cb(uint8_t rhport, audiod_interface_t* audio, uint8_t*
 
     case AUDIO_FORMAT_TYPE_I:
 
-      switch (CFG_TUD_AUDIO_FORMAT_TYPE_I_RX)
+      switch (audio->format_type_I_tx)
       {
         case AUDIO_DATA_FORMAT_TYPE_I_PCM:
-
-#if CFG_TUD_AUDIO_RX_FIFO_SIZE
-          TU_VERIFY(audio_rx_done_type_I_pcm_ff_cb(rhport, audio, buffer, bufsize));
-#else
-#error YOUR DECODING AND BUFFERING IS REQUIRED HERE!
-#endif
+          TU_VERIFY(audiod_decode_type_I_pcm(rhport, audio, n_bytes_received));
           break;
 
         default:
@@ -300,75 +517,159 @@ static bool audio_rx_done_cb(uint8_t rhport, audiod_interface_t* audio, uint8_t*
           break;
   }
 
-  // Call a weak callback here - a possibility for user to get informed RX was completed
-  if (tud_audio_rx_done_cb) TU_VERIFY(tud_audio_rx_done_cb(rhport, buffer, bufsize));
+  // Prepare for next transmission
+  TU_VERIFY(usbd_edpt_xfer(rhport, audio->ep_out, audio->lin_buf_out, audio->ep_out_sz), false);
+
+#else
+
+#if USE_LINEAR_BUFFER_RX
+  // Data currently is in linear buffer, copy into EP OUT FIFO
+  TU_VERIFY(tu_fifo_write_n(&audio->ep_out_ff, audio->lin_buf_out, n_bytes_received));
+
+  // Schedule for next receive
+  TU_VERIFY(usbd_edpt_xfer(rhport, audio->ep_out, audio->lin_buf_out, audio->ep_out_sz), false);
+#else
+  // Data is already placed in EP FIFO, schedule for next receive
+  TU_VERIFY(usbd_edpt_iso_xfer(rhport, audio->ep_out, &audio->ep_out_ff, audio->ep_out_sz), false);
+#endif
+
+#endif
+
+  // Call a weak callback here - a possibility for user to get informed decoding was completed
+  if (tud_audio_rx_done_post_read_cb) TU_VERIFY(tud_audio_rx_done_post_read_cb(rhport, n_bytes_received, idxDriver, audio->ep_out, audio->alt_setting[idxItf]));
 
   return true;
 }
 
-#endif //CFG_TUD_AUDIO_EPSIZE_OUT
+#endif //CFG_TUD_AUDIO_ENABLE_EP_OUT
+
+// The following functions are used in case CFG_TUD_AUDIO_ENABLE_DECODING != 0
+#if CFG_TUD_AUDIO_ENABLE_DECODING && CFG_TUD_AUDIO_ENABLE_EP_OUT
 
-// The following functions are used in case CFG_TUD_AUDIO_RX_FIFO_SIZE != 0
-#if CFG_TUD_AUDIO_RX_FIFO_SIZE
-#if CFG_TUD_AUDIO_RX_FIFO_COUNT > 1
-static bool audio_rx_done_type_I_pcm_ff_cb(uint8_t rhport, audiod_interface_t* audio, uint8_t * buffer, uint16_t bufsize)
+// Decoding according to 2.3.1.5 Audio Streams
+
+// Helper function
+static inline uint8_t * audiod_interleaved_copy_bytes_fast_decode(uint16_t const nBytesToCopy, void * dst, uint8_t * dst_end, uint8_t * src, uint8_t const n_ff_used)
 {
-  (void) rhport;
 
-  // We expect to get a multiple of CFG_TUD_AUDIO_N_BYTES_PER_SAMPLE_RX * CFG_TUD_AUDIO_N_CHANNELS_RX per channel
-  if (bufsize % (CFG_TUD_AUDIO_N_BYTES_PER_SAMPLE_RX * CFG_TUD_AUDIO_N_CHANNELS_RX) != 0)
-  {
-    return false;
-  }
+  // This function is an optimized version of
+  //  while((uint8_t *)dst < dst_end)
+  //  {
+  //    memcpy(dst, src, nBytesToCopy);
+  //    dst = (uint8_t *)dst + nBytesToCopy;
+  //    src += nBytesToCopy * n_ff_used;
+  //  }
 
-  uint8_t chId = 0;
-  uint16_t cnt;
-#if CFG_TUD_AUDIO_N_BYTES_PER_SAMPLE_RX == 1
-  uint8_t sample = 0;
-#elif CFG_TUD_AUDIO_N_BYTES_PER_SAMPLE_RX == 2
-  uint16_t sample = 0;
-#else
-  uint32_t sample = 0;
-#endif
+  // Optimize for fast half word copies
+  typedef struct{
+    uint16_t val;
+  } __attribute((__packed__)) unaligned_uint16_t;
 
-  for(cnt = 0; cnt < bufsize; cnt += CFG_TUD_AUDIO_N_BYTES_PER_SAMPLE_RX)
+  // Optimize for fast word copies
+  typedef struct{
+    uint32_t val;
+  } __attribute((__packed__)) unaligned_uint32_t;
+
+  switch (nBytesToCopy)
   {
-    // Let alignment problems be handled by memcpy
-    memcpy(&sample, &buffer[cnt], CFG_TUD_AUDIO_N_BYTES_PER_SAMPLE_RX);
-    if(tu_fifo_write_n(&audio->rx_ff[chId++], &sample, CFG_TUD_AUDIO_RX_ITEMSIZE) != CFG_TUD_AUDIO_RX_ITEMSIZE)
-    {
-      // Buffer overflow
-      return false;
-    }
+    case 1:
+      while((uint8_t *)dst < dst_end)
+      {
+        *(uint8_t *)dst++ = *src;
+        src += n_ff_used;
+      }
+      break;
 
-    if (chId == CFG_TUD_AUDIO_N_CHANNELS_RX)
-    {
-      chId = 0;
-    }
+    case 2:
+      while((uint8_t *)dst < dst_end)
+      {
+        *(unaligned_uint16_t*)dst = *(unaligned_uint16_t*)src;
+        dst += 2;
+        src += 2 * n_ff_used;
+      }
+      break;
+
+    case 3:
+      while((uint8_t *)dst < dst_end)
+      {
+        //        memcpy(dst, src, 3);
+        //        dst = (uint8_t *)dst + 3;
+        //        src += 3 * n_ff_used;
+
+        // TODO: Is there a faster way to copy 3 bytes?
+        *(uint8_t *)dst++ = *src++;
+        *(uint8_t *)dst++ = *src++;
+        *(uint8_t *)dst++ = *src++;
+
+        src += 3 * (n_ff_used - 1);
+      }
+      break;
+
+    case 4:
+      while((uint8_t *)dst < dst_end)
+      {
+        *(unaligned_uint32_t*)dst = *(unaligned_uint32_t*)src;
+        dst += 4;
+        src += 4 * n_ff_used;
+      }
+      break;
   }
-  return true;
+
+  return src;
 }
-#else
-static bool audio_rx_done_type_I_pcm_ff_cb(uint8_t rhport, audiod_interface_t *audio, uint8_t *buffer, uint16_t bufsize)
+
+static bool audiod_decode_type_I_pcm(uint8_t rhport, audiod_interface_t* audio, uint16_t n_bytes_received)
 {
   (void) rhport;
 
-  // We expect to get a multiple of CFG_TUD_AUDIO_N_BYTES_PER_SAMPLE_RX * CFG_TUD_AUDIO_N_CHANNELS_RX per channel
-  if (bufsize % (CFG_TUD_AUDIO_N_BYTES_PER_SAMPLE_RX * CFG_TUD_AUDIO_N_CHANNELS_RX) != 0)
+  // Determine amount of samples
+  uint8_t const n_ff_used               = audio->n_ff_used_rx;
+  uint16_t const nBytesToCopy           = audio->n_channels_per_ff_rx * audio->n_bytes_per_sampe_rx;
+  uint16_t const nBytesPerFFToRead      = n_bytes_received / n_ff_used;
+  uint8_t cnt_ff;
+
+  // Decode
+  void * dst;
+  uint8_t * src;
+  uint8_t * dst_end;
+  uint16_t len;
+
+  for (cnt_ff = 0; cnt_ff < n_ff_used; cnt_ff++)
   {
-    return false;
+    src = &audio->lin_buf_out[cnt_ff*audio->n_channels_per_ff_rx * audio->n_bytes_per_sampe_rx];
+
+    len = tu_fifo_get_linear_write_info(&audio->rx_supp_ff[cnt_ff], 0, &dst, nBytesPerFFToRead);
+    tu_fifo_advance_write_pointer(&audio->rx_supp_ff[cnt_ff], len);
+
+    dst_end = dst + len;
+
+    src = audiod_interleaved_copy_bytes_fast_decode(nBytesToCopy, dst, dst_end, src, n_ff_used);
+
+    // Handle wrapped part of FIFO
+    if (len < nBytesPerFFToRead)
+    {
+      len = tu_fifo_get_linear_write_info(&audio->rx_supp_ff[cnt_ff], 0, &dst, nBytesPerFFToRead - len);
+      tu_fifo_advance_write_pointer(&audio->rx_supp_ff[cnt_ff], len);
+
+      dst_end = dst + len;
+
+      audiod_interleaved_copy_bytes_fast_decode(nBytesToCopy, dst, dst_end, src, n_ff_used);
+    }
   }
 
-  tu_fifo_write_n(&audio->rx_ff[0], buffer, bufsize);
+  // Number of bytes should be a multiple of CFG_TUD_AUDIO_N_BYTES_PER_SAMPLE_RX * CFG_TUD_AUDIO_N_CHANNELS_RX but checking makes no sense - no way to correct it
+  // TU_VERIFY(cnt != n_bytes);
+
   return true;
 }
-#endif // CFG_TUD_AUDIO_RX_FIFO_COUNT > 1
-#endif //CFG_TUD_AUDIO_RX_FIFO_SIZE
+#endif //CFG_TUD_AUDIO_ENABLE_DECODING
 
 //--------------------------------------------------------------------+
 // WRITE API
 //--------------------------------------------------------------------+
 
+#if CFG_TUD_AUDIO_ENABLE_EP_IN && !CFG_TUD_AUDIO_ENABLE_ENCODING
+
 /**
  * \brief           Write data to EP in buffer
  *
@@ -380,137 +681,118 @@ static bool audio_rx_done_type_I_pcm_ff_cb(uint8_t rhport, audiod_interface_t *a
  * \param[in]       len: # of array elements to copy
  * \return          Number of bytes actually written
  */
-#if CFG_TUD_AUDIO_EPSIZE_IN
-#if !CFG_TUD_AUDIO_TX_FIFO_SIZE
-/*  This function is intended for later use once EP buffers (at least for ISO EPs) are implemented as ring buffers
-uint16_t tud_audio_n_write_ep_in_buffer(uint8_t itf, const void * data, uint16_t len)
+uint16_t tud_audio_n_write(uint8_t itf, const void * data, uint16_t len)
 {
-  audiod_interface_t* audio = &_audiod_itf[itf];
-  if (audio->p_desc == NULL) {
-    return 0;
-  }
+  TU_VERIFY(itf < CFG_TUD_AUDIO && _audiod_itf[itf].p_desc != NULL);
+  return tu_fifo_write_n(&_audiod_itf[itf].ep_in_ff, data, len);
+}
 
-  // THIS IS A CRITICAL SECTION - audio->epin_buf_cnt MUST NOT BE MODIFIED FROM HERE - happens if audiod_tx_done_cb() is executed in between!
+bool tud_audio_n_clear_ep_in_ff(uint8_t itf)                          // Delete all content in the EP IN FIFO
+{
+  TU_VERIFY(itf < CFG_TUD_AUDIO && _audiod_itf[itf].p_desc != NULL);
+  return tu_fifo_clear(&_audiod_itf[itf].ep_in_ff);
+}
 
-  // FOR SINGLE THREADED OPERATION:
-  // AS LONG AS THIS FUNCTION IS NOT EXECUTED WITHIN AN INTERRUPT ALL IS FINE!
+#endif
 
-  // Determine free space
-  uint16_t free = CFG_TUD_AUDIO_EPSIZE_IN - audio->epin_buf_cnt;
+#if CFG_TUD_AUDIO_ENABLE_ENCODING && CFG_TUD_AUDIO_ENABLE_EP_IN
+uint16_t tud_audio_n_flush_tx_support_ff(uint8_t itf)                 // Force all content in the support TX FIFOs to be written into linear buffer and schedule a transmit
+{
+  TU_VERIFY(itf < CFG_TUD_AUDIO && _audiod_itf[itf].p_desc != NULL);
+  audiod_interface_t* audio = &_audiod_itf[itf];
 
-  // Clip length if needed
-  if (len > free) len = free;
+  uint16_t n_bytes_copied = tu_fifo_count(&audio->tx_supp_ff[0]);
 
-  // Write data
-  memcpy((void *) &audio->epin_buf[audio->epin_buf_cnt], data, len);
+  TU_VERIFY(audiod_tx_done_cb(audio->rhport, audio));
 
-  audio->epin_buf_cnt += len;
+  n_bytes_copied -= tu_fifo_count(&audio->tx_supp_ff[0]);
+  n_bytes_copied = n_bytes_copied*audio->tx_supp_ff[0].item_size;
 
-  // Return number of bytes written
-  return len;
+  return n_bytes_copied;
 }
-*/
-
-#else
 
-#if CFG_TUD_AUDIO_TX_FIFO_COUNT == 1
-uint16_t tud_audio_n_write(uint8_t itf, void const* data, uint16_t len)
+bool tud_audio_n_clear_tx_support_ff(uint8_t itf, uint8_t channelId)
 {
-  {
-    audiod_interface_t* audio = &_audiod_itf[itf];
-    if (audio->p_desc == NULL)
-    {
-      return 0;
-    }
-    return tu_fifo_write_n(&audio->tx_ff[0], data, len);
-  }
+  TU_VERIFY(itf < CFG_TUD_AUDIO && _audiod_itf[itf].p_desc != NULL, channelId < _audiod_itf[itf].n_tx_supp_ff);
+  return tu_fifo_clear(&_audiod_itf[itf].tx_supp_ff[channelId]);
 }
-#else
-uint16_t tud_audio_n_write(uint8_t itf, uint8_t channelId, const void * data, uint16_t len)
-{
-  audiod_interface_t* audio = &_audiod_itf[itf];
-  if (audio->p_desc == NULL) {
-    return 0;
-  }
 
-  return tu_fifo_write_n(&audio->tx_ff[channelId], data, len);
+uint16_t tud_audio_n_write_support_ff(uint8_t itf, uint8_t channelId, const void * data, uint16_t len)
+{
+  TU_VERIFY(itf < CFG_TUD_AUDIO && _audiod_itf[itf].p_desc != NULL, channelId < _audiod_itf[itf].n_tx_supp_ff);
+  return tu_fifo_write_n(&_audiod_itf[itf].tx_supp_ff[channelId], data, len);
 }
 #endif
 
-static bool audiod_tx_done_cb(uint8_t rhport, audiod_interface_t* audio, uint16_t * n_bytes_copied);
 
-uint16_t tud_audio_n_write_flush(uint8_t itf)
+#if CFG_TUD_AUDIO_INT_CTR_EPSIZE_IN
+
+// If no interrupt transmit is pending bytes get written into buffer and a transmit is scheduled - once transmit completed tud_audio_int_ctr_done_cb() is called in inform user
+uint16_t tud_audio_int_ctr_n_write(uint8_t itf, uint8_t const* buffer, uint16_t len)
 {
-  audiod_interface_t *audio = &_audiod_itf[itf];
-  if (audio->p_desc == NULL) {
-    return 0;
-  }
+  TU_VERIFY(itf < CFG_TUD_AUDIO && _audiod_itf[itf].p_desc != NULL);
 
-  uint16_t n_bytes_copied;
-  TU_VERIFY(audiod_tx_done_cb(audio->rhport, audio, &n_bytes_copied));
-  return n_bytes_copied;
-}
+  // We write directly into the EP's buffer - abort if previous transfer not complete
+  TU_VERIFY(!usbd_edpt_busy(_audiod_itf[itf].rhport, _audiod_itf[itf].ep_int_ctr));
 
-#endif
-#endif
+  // Check length
+  TU_VERIFY(len <= CFG_TUD_AUDIO_INT_CTR_EP_IN_SW_BUFFER_SIZE);
 
-#if CFG_TUD_AUDIO_INT_CTR_EPSIZE_IN > 0
-uint32_t tud_audio_int_ctr_n_write(uint8_t itf, uint8_t const* buffer, uint32_t bufsize)
-{
-  audiod_interface_t* audio = &_audiod_itf[itf];
-  if (audio->p_desc == NULL) {
-    return 0;
-  }
+  memcpy(_audiod_itf[itf].ep_int_ctr_buf, buffer, len);
 
-  return tu_fifo_write_n(&audio->int_ctr_ff, buffer, bufsize);
+  // Schedule transmit
+  TU_VERIFY(usbd_edpt_xfer(_audiod_itf[itf].rhport, _audiod_itf[itf].ep_int_ctr, _audiod_itf[itf].ep_int_ctr_buf, len));
+
+  return true;
 }
 #endif
 
 
 // This function is called once a transmit of an audio packet was successfully completed. Here, we encode samples and place it in IN EP's buffer for next transmission.
-// If you prefer your own (more efficient) implementation suiting your purpose set CFG_TUD_AUDIO_TX_FIFO_SIZE = 0 and use tud_audio_n_write_ep_in_buffer() (NOT IMPLEMENTED SO FAR).
+// If you prefer your own (more efficient) implementation suiting your purpose set CFG_TUD_AUDIO_ENABLE_ENCODING = 0 and use tud_audio_n_write.
 
 // n_bytes_copied - Informs caller how many bytes were loaded. In case n_bytes_copied = 0, a ZLP is scheduled to inform host no data is available for current frame.
-#if CFG_TUD_AUDIO_EPSIZE_IN
-static bool audiod_tx_done_cb(uint8_t rhport, audiod_interface_t* audio, uint16_t * n_bytes_copied)
+#if CFG_TUD_AUDIO_ENABLE_EP_IN
+static bool audiod_tx_done_cb(uint8_t rhport, audiod_interface_t * audio)
 {
   uint8_t idxDriver, idxItf;
   uint8_t const *dummy2;
 
-  // If a callback is used determine current alternate setting of
-  if (tud_audio_tx_done_pre_load_cb || tud_audio_tx_done_post_load_cb)
-  {
-    // Find index of audio streaming interface and index of interface
-    TU_VERIFY(audiod_get_AS_interface_index(audio->ep_in_as_intf_num, &idxDriver, &idxItf, &dummy2));
-  }
+  // If a callback is used determine current alternate setting of - find index of audio streaming interface and index of interface
+  if (tud_audio_tx_done_pre_load_cb || tud_audio_tx_done_post_load_cb) TU_VERIFY(audiod_get_AS_interface_index(audio->ep_in_as_intf_num, &idxDriver, &idxItf, &dummy2));
 
   // Call a weak callback here - a possibility for user to get informed former TX was completed and data gets now loaded into EP in buffer (in case FIFOs are used) or
-  // if no FIFOs are used the user may use this call back to load its data into the EP in buffer by use of tud_audio_n_write_ep_in_buffer().
-  if (tud_audio_tx_done_pre_load_cb) TU_VERIFY(tud_audio_tx_done_pre_load_cb(rhport, idxDriver, audio->ep_in, audio->altSetting[idxItf]));
+  // if no FIFOs are used the user may use this call back to load its data into the EP IN buffer by use of tud_audio_n_write_ep_in_buffer().
+  if (tud_audio_tx_done_pre_load_cb) TU_VERIFY(tud_audio_tx_done_pre_load_cb(rhport, idxDriver, audio->ep_in, audio->alt_setting[idxItf]));
 
-#if CFG_TUD_AUDIO_TX_FIFO_SIZE
-  switch (CFG_TUD_AUDIO_FORMAT_TYPE_TX)
+  // Send everything in ISO EP FIFO
+  uint16_t n_bytes_tx;
+
+  // If support FIFOs are used, encode and schedule transmit
+#if CFG_TUD_AUDIO_ENABLE_ENCODING && CFG_TUD_AUDIO_ENABLE_EP_IN
+  switch (audio->format_type_tx)
   {
     case AUDIO_FORMAT_TYPE_UNDEFINED:
       // INDIVIDUAL ENCODING PROCEDURE REQUIRED HERE!
       TU_LOG2("  Desired CFG_TUD_AUDIO_FORMAT encoding not implemented!\r\n");
       TU_BREAKPOINT();
+      n_bytes_tx = 0;
       break;
 
     case AUDIO_FORMAT_TYPE_I:
 
-      switch (CFG_TUD_AUDIO_FORMAT_TYPE_I_TX)
+      switch (audio->format_type_I_tx)
       {
         case AUDIO_DATA_FORMAT_TYPE_I_PCM:
 
-          TU_VERIFY(audiod_tx_done_type_I_pcm_ff_cb(rhport, audio));
-
+          n_bytes_tx = audiod_encode_type_I_pcm(rhport, audio);
           break;
 
         default:
           // YOUR ENCODING IS REQUIRED HERE!
           TU_LOG2("  Desired CFG_TUD_AUDIO_FORMAT_TYPE_I_TX encoding not implemented!\r\n");
           TU_BREAKPOINT();
+          n_bytes_tx = 0;
           break;
       }
       break;
@@ -519,199 +801,186 @@ static bool audiod_tx_done_cb(uint8_t rhport, audiod_interface_t* audio, uint16_
           // Desired CFG_TUD_AUDIO_FORMAT_TYPE_TX not implemented!
           TU_LOG2("  Desired CFG_TUD_AUDIO_FORMAT_TYPE_TX not implemented!\r\n");
           TU_BREAKPOINT();
+          n_bytes_tx = 0;
           break;
   }
-#endif
-
-  // THIS IS A CRITICAL SECTION - audio->epin_buf_cnt MUST NOT BE MODIFIED FROM HERE - happens if tud_audio_n_write_ep_in_buffer() is executed in between!
 
-  // THIS IS NOT SOLVED SO FAR!
+  TU_VERIFY(usbd_edpt_xfer(rhport, audio->ep_in, audio->lin_buf_in, n_bytes_tx));
 
-  // FOR SINGLE THREADED OPERATION:
-  // THIS FUNCTION IS NOT EXECUTED WITHIN AN INTERRUPT SO IT DOES NOT INTERRUPT tud_audio_n_write_ep_in_buffer()! AS LONG AS tud_audio_n_write_ep_in_buffer() IS NOT EXECUTED WITHIN AN INTERRUPT ALL IS FINE!
-
-  // Schedule transmit
-  TU_VERIFY(usbd_edpt_xfer(rhport, audio->ep_in, audio->epin_buf, audio->epin_buf_cnt));
+#else
+  // No support FIFOs, if no linear buffer required schedule transmit, else put data into linear buffer and schedule
 
-  // Inform how many bytes were copied
-  *n_bytes_copied = audio->epin_buf_cnt;
+  n_bytes_tx = tu_min16(tu_fifo_count(&audio->ep_in_ff), audio->ep_in_sz);      // Limit up to max packet size, more can not be done for ISO
 
-  // Declare EP in buffer empty
-  audio->epin_buf_cnt = 0;
+#if USE_LINEAR_BUFFER_TX
+  tu_fifo_read_n(&audio->ep_in_ff, audio->lin_buf_in, n_bytes_tx);
+  TU_VERIFY(usbd_edpt_xfer(rhport, audio->ep_in, audio->lin_buf_in, n_bytes_tx));
+#else
+  // Send everything in ISO EP FIFO
+  TU_VERIFY(usbd_edpt_iso_xfer(rhport, audio->ep_in, &audio->ep_in_ff, n_bytes_tx));
+#endif
 
-  // TO HERE
+#endif
 
   // Call a weak callback here - a possibility for user to get informed former TX was completed and how many bytes were loaded for the next frame
-  if (tud_audio_tx_done_post_load_cb) TU_VERIFY(tud_audio_tx_done_post_load_cb(rhport, *n_bytes_copied, idxDriver, audio->ep_in, audio->altSetting[idxItf]));
+  if (tud_audio_tx_done_post_load_cb) TU_VERIFY(tud_audio_tx_done_post_load_cb(rhport, n_bytes_tx, idxDriver, audio->ep_in, audio->alt_setting[idxItf]));
 
   return true;
 }
 
-#endif //CFG_TUD_AUDIO_EPSIZE_IN
+#endif //CFG_TUD_AUDIO_ENABLE_EP_IN
 
-#if CFG_TUD_AUDIO_TX_FIFO_SIZE
-#if CFG_TUD_AUDIO_TX_FIFO_COUNT > 1 || (CFG_TUD_AUDIO_N_BYTES_PER_SAMPLE_TX != CFG_TUD_AUDIO_TX_ITEMSIZE)
-static bool audiod_tx_done_type_I_pcm_ff_cb(uint8_t rhport, audiod_interface_t* audio)
-{
-  // We encode directly into IN EP's buffer - abort if previous transfer not complete
-  TU_VERIFY(!usbd_edpt_busy(rhport, audio->ep_in));
+#if CFG_TUD_AUDIO_ENABLE_ENCODING && CFG_TUD_AUDIO_ENABLE_EP_IN
+// Take samples from the support buffer and encode them into the IN EP software FIFO
+// Returns number of bytes written into linear buffer
 
-  // Determine amount of samples
-  uint16_t const nEndpointSampleCapacity = CFG_TUD_AUDIO_EPSIZE_IN / CFG_TUD_AUDIO_N_CHANNELS_TX / CFG_TUD_AUDIO_N_BYTES_PER_SAMPLE_TX;
-  uint16_t nSamplesPerChannelToSend = tu_fifo_count(&audio->tx_ff[0]) / CFG_TUD_AUDIO_TX_ITEMSIZE;
-  uint16_t nBytesToSend;
-  uint8_t cntChannel;
+/* 2.3.1.7.1 PCM Format
+The PCM (Pulse Coded Modulation) format is the most commonly used audio format to represent audio
+data streams. The audio data is not compressed and uses a signed two’s-complement fixed point format. It
+is left-justified (the sign bit is the Msb) and data is padded with trailing zeros to fill the remaining unused
+bits of the subslot. The binary point is located to the right of the sign bit so that all values lie within the
+range [-1, +1)
+ */
 
-  for (cntChannel = 1; cntChannel < CFG_TUD_AUDIO_N_CHANNELS_TX; cntChannel++)
-  {
-    uint16_t const count = tu_fifo_count(&audio->tx_ff[cntChannel]);
-    if (count / CFG_TUD_AUDIO_TX_ITEMSIZE < nSamplesPerChannelToSend)
-    {
-      nSamplesPerChannelToSend = count * CFG_TUD_AUDIO_TX_ITEMSIZE;
-    }
-  }
+/*
+ * This function encodes channels saved within the support FIFOs into one stream by interleaving the PCM samples
+ * in the support FIFOs according to 2.3.1.5 Audio Streams. It does not control justification (left or right) and
+ * does not change the number of bytes per sample.
+ * */
 
-  // Check if there is enough
-  if (nSamplesPerChannelToSend == 0)
+// Helper function
+static inline uint8_t * audiod_interleaved_copy_bytes_fast_encode(uint16_t const nBytesToCopy, void * src, uint8_t * src_end, uint8_t * dst, uint8_t const n_ff_used)
+{
+  // Optimize for fast half word copies
+  typedef struct{
+    uint16_t val;
+  } __attribute((__packed__)) unaligned_uint16_t;
+
+  // Optimize for fast word copies
+  typedef struct{
+    uint32_t val;
+  } __attribute((__packed__)) unaligned_uint32_t;
+
+  switch (nBytesToCopy)
   {
-    audio->epin_buf_cnt = 0;
-    return true;
-  }
+    case 1:
+      while((uint8_t *)src < src_end)
+      {
+        *dst = *(uint8_t *)src++;
+        dst += n_ff_used;
+      }
+      break;
 
-  // Limit to maximum sample number - THIS IS A POSSIBLE ERROR SOURCE IF TOO MANY SAMPLE WOULD NEED TO BE SENT BUT CAN NOT!
-  nSamplesPerChannelToSend = tu_min16(nSamplesPerChannelToSend, nEndpointSampleCapacity);
-  nBytesToSend = nSamplesPerChannelToSend * CFG_TUD_AUDIO_N_CHANNELS_TX * CFG_TUD_AUDIO_N_BYTES_PER_SAMPLE_TX;
+    case 2:
+      while((uint8_t *)src < src_end)
+      {
+        *(unaligned_uint16_t*)dst = *(unaligned_uint16_t*)src;
+        src += 2;
+        dst += 2 * n_ff_used;
+      }
+      break;
 
-  // Encode
-  uint16_t cntSample;
-  uint8_t * pBuff = audio->epin_buf;
-#if CFG_TUD_AUDIO_N_BYTES_PER_SAMPLE_TX == 1
-  uint8_t sample;
-#elif CFG_TUD_AUDIO_N_BYTES_PER_SAMPLE_TX == 2
-  uint16_t sample;
-#else
-  uint32_t sample;
-#endif
+    case 3:
+      while((uint8_t *)src < src_end)
+      {
+        //        memcpy(dst, src, 3);
+        //        src = (uint8_t *)src + 3;
+        //        dst += 3 * n_ff_used;
 
-  // TODO: Big endianess handling
-  for (cntSample = 0; cntSample < nSamplesPerChannelToSend; cntSample++)
-  {
-    for (cntChannel = 0; cntChannel < CFG_TUD_AUDIO_N_CHANNELS_TX; cntChannel++)
-    {
-      // Get sample from buffer
-      tu_fifo_read_n(&audio->tx_ff[cntChannel], &sample, CFG_TUD_AUDIO_TX_ITEMSIZE);
+        // TODO: Is there a faster way to copy 3 bytes?
+        *dst++ = *(uint8_t *)src++;
+        *dst++ = *(uint8_t *)src++;
+        *dst++ = *(uint8_t *)src++;
 
-      // Put it into EP's buffer - Let alignment problems be handled by memcpy
-      memcpy(pBuff, &sample, CFG_TUD_AUDIO_N_BYTES_PER_SAMPLE_TX);
+        dst += 3 * (n_ff_used - 1);
+      }
+      break;
 
-      // Advance pointer
-      pBuff += CFG_TUD_AUDIO_N_BYTES_PER_SAMPLE_TX;
-    }
+    case 4:
+      while((uint8_t *)src < src_end)
+      {
+        *(unaligned_uint32_t*)dst = *(unaligned_uint32_t*)src;
+        src += 4;
+        dst += 4 * n_ff_used;
+      }
+      break;
   }
 
-  audio->epin_buf_cnt = nBytesToSend;
-
-  return true;
+  return dst;
 }
 
-#else
-static bool audiod_tx_done_type_I_pcm_ff_cb(uint8_t rhport, audiod_interface_t* audio)
+static uint16_t audiod_encode_type_I_pcm(uint8_t rhport, audiod_interface_t* audio)
 {
-  // We encode directly into IN EP's buffer - abort if previous transfer not complete
+  // This function relies on the fact that the length of the support FIFOs was configured to be a multiple of the active sample size in bytes s.t. no sample is split within a wrap
+  // This is ensured within set_interface, where the FIFOs are reconfigured according to this size
+
+  // We encode directly into IN EP's linear buffer - abort if previous transfer not complete
   TU_VERIFY(!usbd_edpt_busy(rhport, audio->ep_in));
 
   // Determine amount of samples
-  uint16_t nByteCount = tu_fifo_count(&audio->tx_ff[0]);
-
-  nByteCount = tu_min16(nByteCount, CFG_TUD_AUDIO_EPSIZE_IN);
+  uint8_t const n_ff_used               = audio->n_ff_used_tx;
+  uint16_t const nBytesToCopy           = audio->n_channels_per_ff_tx * audio->n_bytes_per_sampe_tx;
+  uint16_t const capPerFF               = audio->ep_in_sz / n_ff_used;                                        // Sample capacity per FIFO in bytes
+  uint16_t nBytesPerFFToSend            = tu_fifo_count(&audio->tx_supp_ff[0]);
+  uint8_t cnt_ff;
 
-  // Check if there is enough
-  if (nByteCount == 0)
+  for (cnt_ff = 1; cnt_ff < n_ff_used; cnt_ff++)
   {
-    return true;
+    uint16_t const count = tu_fifo_count(&audio->tx_supp_ff[cnt_ff]);
+    if (count < nBytesPerFFToSend)
+    {
+      nBytesPerFFToSend = count;
+    }
   }
 
-  nByteCount = tu_fifo_read_n(&audio->tx_ff[0], audio->epin_buf, nByteCount);
-  audio->epin_buf_cnt = nByteCount;
-
-  return true;
-}
-#endif // CFG_TUD_AUDIO_TX_FIFO_COUNT > 1 || (CFG_TUD_AUDIO_N_BYTES_PER_SAMPLE_TX != CFG_TUD_AUDIO_TX_ITEMSIZE)
+  // Check if there is enough
+  if (nBytesPerFFToSend == 0)    return 0;
 
-#endif //CFG_TUD_AUDIO_TX_FIFO_SIZE
+  // Limit to maximum sample number - THIS IS A POSSIBLE ERROR SOURCE IF TOO MANY SAMPLE WOULD NEED TO BE SENT BUT CAN NOT!
+  nBytesPerFFToSend = tu_min16(nBytesPerFFToSend, capPerFF);
 
-// This function is called once a transmit of an feedback packet was successfully completed. Here, we get the next feedback value to be sent
+  // Round to full number of samples (flooring)
+  nBytesPerFFToSend = (nBytesPerFFToSend / nBytesToCopy) * nBytesToCopy;
 
-#if CFG_TUD_AUDIO_EPSIZE_OUT && CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP
-static bool audio_fb_send(uint8_t rhport, audiod_interface_t *audio)
-{
-  uint8_t fb[4];
+  // Encode
+  void * src;
+  uint8_t * dst;
+  uint8_t * src_end;
   uint16_t len;
 
-  if (audio->fb_val == 0)
-  {
-    len = 0;
-    return true;
-  }
-  else
+  for (cnt_ff = 0; cnt_ff < n_ff_used; cnt_ff++)
   {
-    len = 4;
-    // Here we need to return the feedback value
-    if (rhport == 0)
-    {
-      // For FS format is 10.14
-      fb[0] = (audio->fb_val >> 2) & 0xFF;
-      fb[1] = (audio->fb_val >> 10) & 0xFF;
-      fb[2] = (audio->fb_val >> 18) & 0xFF;
-      // 4th byte is needed to work correctly with MS Windows
-      fb[3] = 0;
-    }
-    else
-    {
-      // For HS format is 16.16
-      fb[0] = (audio->fb_val >> 0) & 0xFF;
-      fb[1] = (audio->fb_val >> 8) & 0xFF;
-      fb[2] = (audio->fb_val >> 16) & 0xFF;
-      fb[3] = (audio->fb_val >> 24) & 0xFF;
-    }
-    return usbd_edpt_xfer(rhport, audio->ep_fb, fb, len);
-  }
+    dst = &audio->lin_buf_in[cnt_ff*audio->n_channels_per_ff_tx*audio->n_bytes_per_sampe_tx];
 
-}
-
-//static uint16_t audio_fb_done_cb(uint8_t rhport, audiod_interface_t* audio)
-//{
-//  (void) rhport;
-//  (void) audio;
-//
-//  if (tud_audio_fb_done_cb) TU_VERIFY(tud_audio_fb_done_cb(rhport));
-//  return 0;
-//}
+    len = tu_fifo_get_linear_read_info(&audio->tx_supp_ff[cnt_ff], 0, &src, nBytesPerFFToSend);
+    tu_fifo_advance_read_pointer(&audio->tx_supp_ff[cnt_ff], len);
 
-#endif
+    src_end = src + len;
 
-// This function is called once a transmit of an interrupt control packet was successfully completed. Here, we get the remaining bytes to send
+    dst = audiod_interleaved_copy_bytes_fast_encode(nBytesToCopy, src, src_end, dst, n_ff_used);
 
-#if CFG_TUD_AUDIO_INT_CTR_EPSIZE_IN
-static bool audio_int_ctr_done_cb(uint8_t rhport, audiod_interface_t* audio, uint16_t * n_bytes_copied)
-{
-  // We write directly into the EP's buffer - abort if previous transfer not complete
-  TU_VERIFY(!usbd_edpt_busy(rhport, audio->ep_int_ctr));
+    // Handle wrapped part of FIFO
+    if (len < nBytesPerFFToSend)
+    {
+      len = tu_fifo_get_linear_read_info(&audio->tx_supp_ff[cnt_ff], 0, &src, nBytesPerFFToSend - len);
+      tu_fifo_advance_read_pointer(&audio->tx_supp_ff[cnt_ff], len);
 
-  // TODO: Big endianess handling
-  uint16_t cnt = tu_fifo_read_n(audio->int_ctr_ff, audio->ep_int_ctr_buf, CFG_TUD_AUDIO_INT_CTR_EPSIZE_IN);
+      src_end = src + len;
 
-  if (cnt > 0)
-  {
-    // Schedule transmit
-    TU_VERIFY(usbd_edpt_xfer(rhport, audio->ep_int_ctr, audio->ep_int_ctr_buf, cnt));
+      audiod_interleaved_copy_bytes_fast_encode(nBytesToCopy, src, src_end, dst, n_ff_used);
+    }
   }
 
-  *n_bytes_copied = cnt;
+  return nBytesPerFFToSend * n_ff_used;
+}
+#endif //CFG_TUD_AUDIO_ENABLE_ENCODING
 
-  if (tud_audio_int_ctr_done_cb) TU_VERIFY(tud_audio_int_ctr_done_cb(rhport, n_bytes_copied));
+// This function is called once a transmit of a feedback packet was successfully completed. Here, we get the next feedback value to be sent
 
-  return true;
+#if CFG_TUD_AUDIO_ENABLE_EP_OUT && CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP
+static inline bool audiod_fb_send(uint8_t rhport, audiod_interface_t *audio)
+{
+  return usbd_edpt_xfer(rhport, audio->ep_fb, (uint8_t *) &audio->fb_val, 4);
 }
 #endif
 
@@ -726,33 +995,308 @@ void audiod_init(void)
   {
     audiod_interface_t* audio = &_audiod_itf[i];
 
-    // Initialize TX FIFOs if required
-#if CFG_TUD_AUDIO_EPSIZE_IN && CFG_TUD_AUDIO_TX_FIFO_SIZE
-    for (uint8_t cnt = 0; cnt < CFG_TUD_AUDIO_TX_FIFO_COUNT; cnt++)
+    // Initialize control buffers
+    switch (i)
     {
-      tu_fifo_config(&audio->tx_ff[cnt], &audio->tx_ff_buf[cnt], CFG_TUD_AUDIO_TX_FIFO_SIZE, 1, true);
+      case 0:
+        audio->ctrl_buf = ctrl_buf_1;
+        audio->ctrl_buf_sz = CFG_TUD_AUDIO_FUNC_1_CTRL_BUF_SZ;
+        break;
+#if CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_CTRL_BUF_SZ > 0
+      case 1:
+        audio->ctrl_buf = ctrl_buf_2;
+        audio->ctrl_buf_sz = CFG_TUD_AUDIO_FUNC_2_CTRL_BUF_SZ;
+        break;
+#endif
+#if CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_CTRL_BUF_SZ > 0
+      case 2:
+        audio->ctrl_buf = ctrl_buf_3;
+        audio->ctrl_buf_sz = CFG_TUD_AUDIO_FUNC_3_CTRL_BUF_SZ;
+        break;
+#endif
+    }
+
+    // Initialize active alternate interface buffers
+    switch (i)
+    {
+#if CFG_TUD_AUDIO_FUNC_1_N_AS_INT > 0
+      case 0:
+        audio->alt_setting = alt_setting_1;
+        break;
+#endif
+#if CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_N_AS_INT > 0
+      case 1:
+        audio->alt_setting = alt_setting_2;
+        break;
+#endif
+#if CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_N_AS_INT > 0
+      case 2:
+        audio->alt_setting = alt_setting_3;
+        break;
+#endif
+    }
+
+    // Initialize IN EP FIFO if required
+#if CFG_TUD_AUDIO_ENABLE_EP_IN && !CFG_TUD_AUDIO_ENABLE_ENCODING
+
+    switch (i)
+    {
+#if CFG_TUD_AUDIO_FUNC_1_EP_IN_SW_BUF_SZ > 0
+      case 0:
+        tu_fifo_config(&audio->ep_in_ff, audio_ep_in_sw_buf_1, CFG_TUD_AUDIO_FUNC_1_EP_IN_SW_BUF_SZ, 1, true);
+#if CFG_FIFO_MUTEX
+        tu_fifo_config_mutex(&audio->ep_in_ff, osal_mutex_create(&ep_in_ff_mutex_wr_1), NULL);
+#endif
+        break;
+#endif
+#if CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_EP_IN_SW_BUF_SZ > 0
+      case 1:
+        tu_fifo_config(&audio->ep_in_ff, audio_ep_in_sw_buf_2, CFG_TUD_AUDIO_FUNC_2_EP_IN_SW_BUF_SZ, 1, true);
+#if CFG_FIFO_MUTEX
+        tu_fifo_config_mutex(&audio->ep_in_ff, osal_mutex_create(&ep_in_ff_mutex_wr_2), NULL);
+#endif
+        break;
+#endif
+#if CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_EP_IN_SW_BUF_SZ > 0
+      case 2:
+        tu_fifo_config(&audio->ep_in_ff, audio_ep_in_sw_buf_3, CFG_TUD_AUDIO_FUNC_3_EP_IN_SW_BUF_SZ, 1, true);
+#if CFG_FIFO_MUTEX
+        tu_fifo_config_mutex(&audio->ep_in_ff, osal_mutex_create(&ep_in_ff_mutex_wr_3), NULL);
+#endif
+        break;
+#endif
+    }
+#endif // CFG_TUD_AUDIO_ENABLE_EP_IN && !CFG_TUD_AUDIO_ENABLE_ENCODING
+
+    // Initialize linear buffers
+#if USE_LINEAR_BUFFER_TX
+    switch (i)
+    {
+#if CFG_TUD_AUDIO_FUNC_1_EP_IN_SZ_MAX > 0
+      case 0:
+        audio->lin_buf_in = lin_buf_in_1;
+        break;
+#endif
+#if CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_EP_IN_SZ_MAX > 0
+      case 1:
+        audio->lin_buf_in = lin_buf_in_2;
+        break;
+#endif
+#if CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_EP_IN_SZ_MAX > 0
+      case 2:
+        audio->lin_buf_in = lin_buf_in_3;
+        break;
+#endif
+    }
+#endif // USE_LINEAR_BUFFER_TX
+
+    // Initialize OUT EP FIFO if required
+#if CFG_TUD_AUDIO_ENABLE_EP_OUT && !CFG_TUD_AUDIO_ENABLE_DECODING
+
+    switch (i)
+    {
+#if CFG_TUD_AUDIO_FUNC_1_EP_OUT_SW_BUF_SZ > 0
+      case 0:
+        tu_fifo_config(&audio->ep_out_ff, audio_ep_out_sw_buf_1, CFG_TUD_AUDIO_FUNC_1_EP_OUT_SW_BUF_SZ, 1, true);
+#if CFG_FIFO_MUTEX
+        tu_fifo_config_mutex(&audio->ep_out_ff, NULL, osal_mutex_create(&ep_out_ff_mutex_rd_1));
+#endif
+        break;
+#endif
+#if CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_EP_OUT_SW_BUF_SZ > 0
+      case 1:
+        tu_fifo_config(&audio->ep_out_ff, audio_ep_out_sw_buf_2, CFG_TUD_AUDIO_FUNC_2_EP_OUT_SW_BUF_SZ, 1, true);
+#if CFG_FIFO_MUTEX
+        tu_fifo_config_mutex(&audio->ep_out_ff, NULL, osal_mutex_create(&ep_out_ff_mutex_rd_2));
+#endif
+        break;
+#endif
+#if CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_EP_OUT_SW_BUF_SZ > 0
+      case 2:
+        tu_fifo_config(&audio->ep_out_ff, audio_ep_out_sw_buf_3, CFG_TUD_AUDIO_FUNC_3_EP_OUT_SW_BUF_SZ, 1, true);
 #if CFG_FIFO_MUTEX
-      tu_fifo_config_mutex(&audio->tx_ff[cnt], osal_mutex_create(&audio->tx_ff_mutex[cnt]));
+        tu_fifo_config_mutex(&audio->ep_out_ff, NULL, osal_mutex_create(&ep_out_ff_mutex_rd_3));
+#endif
+        break;
 #endif
     }
+#endif // CFG_TUD_AUDIO_ENABLE_EP_OUT && !CFG_TUD_AUDIO_ENABLE_DECODING
+
+    // Initialize linear buffers
+#if USE_LINEAR_BUFFER_RX
+    switch (i)
+    {
+#if CFG_TUD_AUDIO_FUNC_1_EP_OUT_SZ_MAX > 0
+      case 0:
+        audio->lin_buf_out = lin_buf_out_1;
+        break;
 #endif
+#if CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_EP_OUT_SZ_MAX > 0
+      case 1:
+        audio->lin_buf_out = lin_buf_out_2;
+        break;
+#endif
+#if CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_EP_OUT_SZ_MAX > 0
+      case 2:
+        audio->lin_buf_out = lin_buf_out_3;
+        break;
+#endif
+    }
+#endif // USE_LINEAR_BUFFER_TX
+
+    // Initialize TX support FIFOs if required
+#if CFG_TUD_AUDIO_ENABLE_EP_IN && CFG_TUD_AUDIO_ENABLE_ENCODING
 
-#if CFG_TUD_AUDIO_EPSIZE_OUT && CFG_TUD_AUDIO_RX_FIFO_SIZE
-    for (uint8_t cnt = 0; cnt < CFG_TUD_AUDIO_RX_FIFO_COUNT; cnt++)
+    switch (i)
     {
-      tu_fifo_config(&audio->rx_ff[cnt], &audio->rx_ff_buf[cnt], CFG_TUD_AUDIO_RX_FIFO_SIZE, 1, true);
+#if CFG_TUD_AUDIO_FUNC_1_TX_SUPP_SW_FIFO_SZ > 0
+      case 0:
+        audio->tx_supp_ff = tx_supp_ff_1;
+        audio->n_tx_supp_ff = CFG_TUD_AUDIO_FUNC_1_N_TX_SUPP_SW_FIFO;
+        audio->tx_supp_ff_sz_max = CFG_TUD_AUDIO_FUNC_1_TX_SUPP_SW_FIFO_SZ;
+        for (uint8_t cnt = 0; cnt < CFG_TUD_AUDIO_FUNC_1_N_TX_SUPP_SW_FIFO; cnt++)
+        {
+          tu_fifo_config(&tx_supp_ff_1[cnt], tx_supp_ff_buf_1[cnt], CFG_TUD_AUDIO_FUNC_1_TX_SUPP_SW_FIFO_SZ, 1, true);
+#if CFG_FIFO_MUTEX
+          tu_fifo_config_mutex(&tx_supp_ff_1[cnt], osal_mutex_create(&tx_supp_ff_mutex_wr_1[cnt]), NULL);
+#endif
+        }
+
+        break;
+#endif // CFG_TUD_AUDIO_FUNC_1_TX_SUPP_SW_FIFO_SZ > 0
+
+#if CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_TX_SUPP_SW_FIFO_SZ > 0
+      case 1:
+        audio->tx_supp_ff = tx_supp_ff_2;
+        audio->n_tx_supp_ff = CFG_TUD_AUDIO_FUNC_2_N_TX_SUPP_SW_FIFO;
+        audio->tx_supp_ff_sz_max = CFG_TUD_AUDIO_FUNC_2_TX_SUPP_SW_FIFO_SZ;
+        for (uint8_t cnt = 0; cnt < CFG_TUD_AUDIO_FUNC_2_N_TX_SUPP_SW_FIFO; cnt++)
+        {
+          tu_fifo_config(&tx_supp_ff_2[cnt], tx_supp_ff_buf_2[cnt], CFG_TUD_AUDIO_FUNC_2_TX_SUPP_SW_FIFO_SZ, 1, true);
 #if CFG_FIFO_MUTEX
-      tu_fifo_config_mutex(&audio->rx_ff[cnt], osal_mutex_create(&audio->rx_ff_mutex[cnt]));
+          tu_fifo_config_mutex(&tx_supp_ff_2[cnt], osal_mutex_create(&tx_supp_ff_mutex_wr_2[cnt]), NULL);
 #endif
+        }
+
+        break;
+#endif // CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_TX_SUPP_SW_FIFO_SZ > 0
+
+#if CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_TX_SUPP_SW_FIFO_SZ > 0
+      case 2:
+        audio->tx_supp_ff = tx_supp_ff_3;
+        audio->n_tx_supp_ff = CFG_TUD_AUDIO_FUNC_3_N_TX_SUPP_SW_FIFO;
+        audio->tx_supp_ff_sz_max = CFG_TUD_AUDIO_FUNC_3_TX_SUPP_SW_FIFO_SZ;
+        for (uint8_t cnt = 0; cnt < CFG_TUD_AUDIO_FUNC_3_N_TX_SUPP_SW_FIFO; cnt++)
+        {
+          tu_fifo_config(&tx_supp_ff_3[cnt], tx_supp_ff_buf_3[cnt], CFG_TUD_AUDIO_FUNC_3_TX_SUPP_SW_FIFO_SZ, 1, true);
+#if CFG_FIFO_MUTEX
+          tu_fifo_config_mutex(&tx_supp_ff_3[cnt], osal_mutex_create(&tx_supp_ff_mutex_wr_3[cnt]), NULL);
+#endif
+        }
+
+        break;
+#endif // CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_TX_SUPP_SW_FIFO_SZ > 0
     }
+#endif // CFG_TUD_AUDIO_ENABLE_EP_IN && CFG_TUD_AUDIO_ENABLE_ENCODING
+
+    // Set encoding parameters for Type_I formats
+#if CFG_TUD_AUDIO_ENABLE_TYPE_I_ENCODING
+    switch (i)
+    {
+#if CFG_TUD_AUDIO_FUNC_1_TX_SUPP_SW_FIFO_SZ > 0
+      case 0:
+        audio->n_channels_per_ff_tx = CFG_TUD_AUDIO_FUNC_1_CHANNEL_PER_FIFO_TX;
+        break;
+#endif
+#if CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_TX_SUPP_SW_FIFO_SZ > 0
+      case 1:
+        audio->n_channels_per_ff_tx = CFG_TUD_AUDIO_FUNC_2_CHANNEL_PER_FIFO_TX;
+        break;
+#endif
+#if CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_TX_SUPP_SW_FIFO_SZ > 0
+      case 2:
+        audio->n_channels_per_ff_tx = CFG_TUD_AUDIO_FUNC_3_CHANNEL_PER_FIFO_TX;
+        break;
+#endif
+    }
+#endif // CFG_TUD_AUDIO_ENABLE_TYPE_I_ENCODING
+
+    // Initialize RX support FIFOs if required
+#if CFG_TUD_AUDIO_ENABLE_EP_OUT && CFG_TUD_AUDIO_ENABLE_DECODING
+
+    switch (i)
+    {
+#if CFG_TUD_AUDIO_FUNC_1_RX_SUPP_SW_FIFO_SZ > 0
+      case 0:
+        audio->rx_supp_ff = rx_supp_ff_1;
+        audio->n_rx_supp_ff = CFG_TUD_AUDIO_FUNC_1_N_RX_SUPP_SW_FIFO;
+        audio->rx_supp_ff_sz_max = CFG_TUD_AUDIO_FUNC_1_RX_SUPP_SW_FIFO_SZ;
+        for (uint8_t cnt = 0; cnt < CFG_TUD_AUDIO_FUNC_1_N_RX_SUPP_SW_FIFO; cnt++)
+        {
+          tu_fifo_config(&rx_supp_ff_1[cnt], rx_supp_ff_buf_1[cnt], CFG_TUD_AUDIO_FUNC_1_RX_SUPP_SW_FIFO_SZ, 1, true);
+#if CFG_FIFO_MUTEX
+          tu_fifo_config_mutex(&rx_supp_ff_1[cnt], osal_mutex_create(&rx_supp_ff_mutex_rd_1[cnt]), NULL);
 #endif
+        }
+
+        break;
+#endif // CFG_TUD_AUDIO_FUNC_1_RX_SUPP_SW_FIFO_SZ > 0
 
-#if CFG_TUD_AUDIO_INT_CTR_EPSIZE_IN > 0
-    tu_fifo_config(&audio->int_ctr_ff, &audio->int_ctr_ff_buf, CFG_TUD_AUDIO_INT_CTR_BUFSIZE, 1, true);
+#if CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_RX_SUPP_SW_FIFO_SZ > 0
+      case 1:
+        audio->rx_supp_ff = rx_supp_ff_2;
+        audio->n_rx_supp_ff = CFG_TUD_AUDIO_FUNC_2_N_RX_SUPP_SW_FIFO;
+        audio->rx_supp_ff_sz_max = CFG_TUD_AUDIO_FUNC_2_RX_SUPP_SW_FIFO_SZ;
+        for (uint8_t cnt = 0; cnt < CFG_TUD_AUDIO_FUNC_2_N_RX_SUPP_SW_FIFO; cnt++)
+        {
+          tu_fifo_config(&rx_supp_ff_2[cnt], rx_supp_ff_buf_2[cnt], CFG_TUD_AUDIO_FUNC_2_RX_SUPP_SW_FIFO_SZ, 1, true);
 #if CFG_FIFO_MUTEX
-    tu_fifo_config_mutex(&audio->int_ctr_ff, osal_mutex_create(&audio->int_ctr_ff_mutex));
+          tu_fifo_config_mutex(&rx_supp_ff_2[cnt], osal_mutex_create(&rx_supp_ff_mutex_rd_2[cnt]), NULL);
 #endif
+        }
+
+        break;
+#endif // CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_RX_SUPP_SW_FIFO_SZ > 0
+
+#if CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_RX_SUPP_SW_FIFO_SZ > 0
+      case 2:
+        audio->rx_supp_ff = rx_supp_ff_3;
+        audio->n_rx_supp_ff = CFG_TUD_AUDIO_FUNC_3_N_RX_SUPP_SW_FIFO;
+        audio->rx_supp_ff_sz_max = CFG_TUD_AUDIO_FUNC_3_RX_SUPP_SW_FIFO_SZ;
+        for (uint8_t cnt = 0; cnt < CFG_TUD_AUDIO_FUNC_3_N_RX_SUPP_SW_FIFO; cnt++)
+        {
+          tu_fifo_config(&rx_supp_ff_3[cnt], rx_supp_ff_buf_3[cnt], CFG_TUD_AUDIO_FUNC_3_RX_SUPP_SW_FIFO_SZ, 1, true);
+#if CFG_FIFO_MUTEX
+          tu_fifo_config_mutex(&rx_supp_ff_3[cnt], osal_mutex_create(&rx_supp_ff_mutex_rd_3[cnt]), NULL);
 #endif
+        }
+
+        break;
+#endif // CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_RX_SUPP_SW_FIFO_SZ > 0
+    }
+#endif // CFG_TUD_AUDIO_ENABLE_EP_IN && CFG_TUD_AUDIO_ENABLE_ENCODING
+
+    // Set encoding parameters for Type_I formats
+#if CFG_TUD_AUDIO_ENABLE_TYPE_I_DECODING
+    switch (i)
+    {
+#if CFG_TUD_AUDIO_FUNC_1_RX_SUPP_SW_FIFO_SZ > 0
+      case 0:
+        audio->n_channels_per_ff_rx = CFG_TUD_AUDIO_FUNC_1_CHANNEL_PER_FIFO_RX;
+        break;
+#endif
+#if CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_RX_SUPP_SW_FIFO_SZ > 0
+      case 1:
+        audio->n_channels_per_ff_rx = CFG_TUD_AUDIO_FUNC_2_CHANNEL_PER_FIFO_RX;
+        break;
+#endif
+#if CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_RX_SUPP_SW_FIFO_SZ > 0
+      case 2:
+        audio->n_channels_per_ff_rx = CFG_TUD_AUDIO_FUNC_3_CHANNEL_PER_FIFO_RX;
+        break;
+#endif
+    }
+#endif // CFG_TUD_AUDIO_ENABLE_TYPE_I_DECODING
   }
 }
 
@@ -765,17 +1309,25 @@ void audiod_reset(uint8_t rhport)
     audiod_interface_t* audio = &_audiod_itf[i];
     tu_memclr(audio, ITF_MEM_RESET_SIZE);
 
-#if CFG_TUD_AUDIO_EPSIZE_IN && CFG_TUD_AUDIO_TX_FIFO_SIZE
-    for (uint8_t cnt = 0; cnt < CFG_TUD_AUDIO_TX_FIFO_COUNT; cnt++)
+#if CFG_TUD_AUDIO_ENABLE_EP_IN && !CFG_TUD_AUDIO_ENABLE_ENCODING
+    tu_fifo_clear(&audio->ep_in_ff);
+#endif
+
+#if CFG_TUD_AUDIO_ENABLE_EP_OUT && !CFG_TUD_AUDIO_ENABLE_DECODING
+    tu_fifo_clear(&audio->ep_out_ff);
+#endif
+
+#if CFG_TUD_AUDIO_ENABLE_EP_IN && CFG_TUD_AUDIO_ENABLE_ENCODING
+    for (uint8_t cnt = 0; cnt < audio->n_tx_supp_ff; cnt++)
     {
-      tu_fifo_clear(&audio->tx_ff[cnt]);
+      tu_fifo_clear(&audio->tx_supp_ff[cnt]);
     }
 #endif
 
-#if CFG_TUD_AUDIO_EPSIZE_OUT && CFG_TUD_AUDIO_RX_FIFO_SIZE
-    for (uint8_t cnt = 0; cnt < CFG_TUD_AUDIO_RX_FIFO_COUNT; cnt++)
+#if CFG_TUD_AUDIO_ENABLE_EP_OUT && CFG_TUD_AUDIO_ENABLE_DECODING
+    for (uint8_t cnt = 0; cnt < audio->n_rx_supp_ff; cnt++)
     {
-      tu_fifo_clear(&audio->rx_ff[cnt]);
+      tu_fifo_clear(&audio->rx_supp_ff[cnt]);
     }
 #endif
   }
@@ -808,6 +1360,25 @@ uint16_t audiod_open(uint8_t rhport, tusb_desc_interface_t const * itf_desc, uin
     {
       _audiod_itf[i].p_desc = (uint8_t const *)itf_desc;    // Save pointer to AC descriptor which is by specification always the first one
       _audiod_itf[i].rhport = rhport;
+
+      // Setup descriptor lengths
+      switch (i)
+      {
+        case 0:
+          _audiod_itf[i].desc_length = CFG_TUD_AUDIO_FUNC_1_DESC_LEN;
+          break;
+#if CFG_TUD_AUDIO > 1
+        case 1:
+          _audiod_itf[i].desc_length = CFG_TUD_AUDIO_FUNC_2_DESC_LEN;
+          break;
+#endif
+#if CFG_TUD_AUDIO > 2
+        case 2:
+          _audiod_itf[i].desc_length = CFG_TUD_AUDIO_FUNC_3_DESC_LEN;
+          break;
+#endif
+      }
+
       break;
     }
   }
@@ -816,15 +1387,13 @@ uint16_t audiod_open(uint8_t rhport, tusb_desc_interface_t const * itf_desc, uin
   TU_ASSERT( i < CFG_TUD_AUDIO );
 
   // This is all we need so far - the EPs are setup by a later set_interface request (as per UAC2 specification)
-  // TODO: Find a way to find end of current audio function and avoid necessity of tud_audio_desc_lengths - since now max_length is available we could do this surely somehow
-  uint16_t drv_len = tud_audio_desc_lengths[i] - TUD_AUDIO_DESC_IAD_LEN;    // - TUD_AUDIO_DESC_IAD_LEN since tinyUSB already handles the IAD descriptor
+  uint16_t drv_len = _audiod_itf[i].desc_length - TUD_AUDIO_DESC_IAD_LEN;    // - TUD_AUDIO_DESC_IAD_LEN since tinyUSB already handles the IAD descriptor
 
   return drv_len;
 }
 
 static bool audiod_get_interface(uint8_t rhport, tusb_control_request_t const * p_request)
 {
-#if CFG_TUD_AUDIO_N_AS_INT > 0
   uint8_t const itf = tu_u16_low(p_request->wIndex);
 
   // Find index of audio streaming interface
@@ -832,17 +1401,11 @@ static bool audiod_get_interface(uint8_t rhport, tusb_control_request_t const *
   uint8_t const *dummy;
 
   TU_VERIFY(audiod_get_AS_interface_index(itf, &idxDriver, &idxItf, &dummy));
-  TU_VERIFY(tud_control_xfer(rhport, p_request, &_audiod_itf[idxDriver].altSetting[idxItf], 1));
+  TU_VERIFY(tud_control_xfer(rhport, p_request, &_audiod_itf[idxDriver].alt_setting[idxItf], 1));
 
-  TU_LOG2("  Get itf: %u - current alt: %u\r\n", itf, _audiod_itf[idxDriver].altSetting[idxItf]);
+  TU_LOG2("  Get itf: %u - current alt: %u\r\n", itf, _audiod_itf[idxDriver].alt_setting[idxItf]);
 
   return true;
-
-#else
-  (void) rhport;
-  (void) p_request;
-  return false;
-#endif
 }
 
 static bool audiod_set_interface(uint8_t rhport, tusb_control_request_t const * p_request)
@@ -870,41 +1433,60 @@ static bool audiod_set_interface(uint8_t rhport, tusb_control_request_t const *
   uint8_t const *p_desc;
   TU_VERIFY(audiod_get_AS_interface_index(itf, &idxDriver, &idxItf, &p_desc));
 
+  audiod_interface_t* audio = &_audiod_itf[idxDriver];
+
   // Look if there is an EP to be closed - for this driver, there are only 3 possible EPs which may be closed (only AS related EPs can be closed, AC EP (if present) is always open)
-#if CFG_TUD_AUDIO_EPSIZE_IN > 0
-  if (_audiod_itf[idxDriver].ep_in_as_intf_num == itf)
+#if CFG_TUD_AUDIO_ENABLE_EP_IN
+  if (audio->ep_in_as_intf_num == itf)
   {
-    _audiod_itf[idxDriver].ep_in_as_intf_num = 0;
-    usbd_edpt_close(rhport, _audiod_itf[idxDriver].ep_in);
+    audio->ep_in_as_intf_num = 0;
+    usbd_edpt_close(rhport, audio->ep_in);
 
     // Invoke callback - can be used to stop data sampling
     if (tud_audio_set_itf_close_EP_cb) TU_VERIFY(tud_audio_set_itf_close_EP_cb(rhport, p_request));
 
-    _audiod_itf[idxDriver].ep_in = 0;                           // Necessary?
+    audio->ep_in = 0;                           // Necessary?
+
+    // Clear support FIFOs if used
+#if CFG_TUD_AUDIO_ENABLE_ENCODING
+    for (uint8_t cnt = 0; cnt < audio->n_tx_supp_ff; cnt++)
+    {
+      tu_fifo_clear(&audio->tx_supp_ff[cnt]);
+    }
+#endif
+
   }
 #endif
 
-#if CFG_TUD_AUDIO_EPSIZE_OUT
-  if (_audiod_itf[idxDriver].ep_out_as_intf_num == itf)
+#if CFG_TUD_AUDIO_ENABLE_EP_OUT
+  if (audio->ep_out_as_intf_num == itf)
   {
-    _audiod_itf[idxDriver].ep_out_as_intf_num = 0;
-    usbd_edpt_close(rhport, _audiod_itf[idxDriver].ep_out);
-    _audiod_itf[idxDriver].ep_out = 0;                          // Necessary?
+    audio->ep_out_as_intf_num = 0;
+    usbd_edpt_close(rhport, audio->ep_out);
+    audio->ep_out = 0;                          // Necessary?
+
+    // Clear support FIFOs if used
+#if CFG_TUD_AUDIO_ENABLE_DECODING
+    for (uint8_t cnt = 0; cnt < audio->n_rx_supp_ff; cnt++)
+    {
+      tu_fifo_clear(&audio->rx_supp_ff[cnt]);
+    }
+#endif
 
     // Close corresponding feedback EP
 #if CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP
-    usbd_edpt_close(rhport, _audiod_itf[idxDriver].ep_fb);
-    _audiod_itf[idxDriver].ep_fb = 0;                           // Necessary?
+    usbd_edpt_close(rhport, audio->ep_fb);
+    audio->ep_fb = 0;                           // Necessary?
 #endif
   }
 #endif
 
   // Save current alternative interface setting
-  _audiod_itf[idxDriver].altSetting[idxItf] = alt;
+  audio->alt_setting[idxItf] = alt;
 
   // Open new EP if necessary - EPs are only to be closed or opened for AS interfaces - Look for AS interface with correct alternate interface
   // Get pointer at end
-  uint8_t const *p_desc_end = _audiod_itf[idxDriver].p_desc + tud_audio_desc_lengths[idxDriver] - TUD_AUDIO_DESC_IAD_LEN;
+  uint8_t const *p_desc_end = audio->p_desc + audio->desc_length - TUD_AUDIO_DESC_IAD_LEN;
 
   // p_desc starts at required interface with alternate setting zero
   while (p_desc < p_desc_end)
@@ -912,6 +1494,9 @@ static bool audiod_set_interface(uint8_t rhport, tusb_control_request_t const *
     // Find correct interface
     if (tu_desc_type(p_desc) == TUSB_DESC_INTERFACE && ((tusb_desc_interface_t const * )p_desc)->bInterfaceNumber == itf && ((tusb_desc_interface_t const * )p_desc)->bAlternateSetting == alt)
     {
+#if CFG_TUD_AUDIO_ENABLE_ENCODING || CFG_TUD_AUDIO_ENABLE_DECODING
+      uint8_t const * p_desc_parse_for_params = p_desc;
+#endif
       // From this point forward follow the EP descriptors associated to the current alternate setting interface - Open EPs if necessary
       uint8_t foundEPs = 0, nEps = ((tusb_desc_interface_t const * )p_desc)->bNumEndpoints;
       while (foundEPs < nEps && p_desc < p_desc_end)
@@ -922,51 +1507,87 @@ static bool audiod_set_interface(uint8_t rhport, tusb_control_request_t const *
 
           uint8_t ep_addr = ((tusb_desc_endpoint_t const *) p_desc)->bEndpointAddress;
 
-          // We need to set EP non busy since this is not taken care of right now in ep_close() - THIS IS A WORKAROUND!
+          //TODO: We need to set EP non busy since this is not taken care of right now in ep_close() - THIS IS A WORKAROUND!
           usbd_edpt_clear_stall(rhport, ep_addr);
 
-#if CFG_TUD_AUDIO_EPSIZE_IN > 0
+#if CFG_TUD_AUDIO_ENABLE_EP_IN
           if (tu_edpt_dir(ep_addr) == TUSB_DIR_IN && ((tusb_desc_endpoint_t const *) p_desc)->bmAttributes.usage == 0x00)   // Check if usage is data EP
           {
             // Save address
-            _audiod_itf[idxDriver].ep_in = ep_addr;
-            _audiod_itf[idxDriver].ep_in_as_intf_num = itf;
+            audio->ep_in = ep_addr;
+            audio->ep_in_as_intf_num = itf;
+            audio->ep_in_sz = ((tusb_desc_endpoint_t const *) p_desc)->wMaxPacketSize.size;
 
+            // If software encoding is enabled, parse for the corresponding parameters - doing this here means only AS interfaces with EPs get scanned for parameters
+#if CFG_TUD_AUDIO_ENABLE_ENCODING
+            audiod_parse_for_AS_params(audio, p_desc_parse_for_params, p_desc_end, itf);
+
+            // Reconfigure size of support FIFOs - this is necessary to avoid samples to get split in case of a wrap
+#if CFG_TUD_AUDIO_ENABLE_TYPE_I_ENCODING
+            const uint16_t active_fifo_depth = (audio->tx_supp_ff_sz_max / audio->n_bytes_per_sampe_tx) * audio->n_bytes_per_sampe_tx;
+            for (uint8_t cnt = 0; cnt < audio->n_tx_supp_ff; cnt++)
+            {
+              tu_fifo_config(&audio->tx_supp_ff[cnt], audio->tx_supp_ff[cnt].buffer, active_fifo_depth, 1, true);
+            }
+            audio->n_ff_used_tx = audio->n_channels_tx / audio->n_channels_per_ff_tx;
+            TU_ASSERT( audio->n_ff_used_tx <= audio->n_tx_supp_ff );
+#endif
+
+#endif
             // Invoke callback - can be used to trigger data sampling if not already running
             if (tud_audio_set_itf_cb) TU_VERIFY(tud_audio_set_itf_cb(rhport, p_request));
 
             // Schedule first transmit - in case no sample data is available a ZLP is loaded
-            uint16_t n_bytes_copied;
-            TU_VERIFY(audiod_tx_done_cb(rhport, &_audiod_itf[idxDriver], &n_bytes_copied));
+            // It is necessary to trigger this here since the refill is done with an RX FIFO empty interrupt which can only trigger if something was in there
+            TU_VERIFY(audiod_tx_done_cb(rhport, &_audiod_itf[idxDriver]));
           }
-#endif
+#endif // CFG_TUD_AUDIO_ENABLE_EP_IN
 
-#if CFG_TUD_AUDIO_EPSIZE_OUT
+#if CFG_TUD_AUDIO_ENABLE_EP_OUT
 
           if (tu_edpt_dir(ep_addr) == TUSB_DIR_OUT)     // Checking usage not necessary
           {
             // Save address
-            _audiod_itf[idxDriver].ep_out = ep_addr;
-            _audiod_itf[idxDriver].ep_out_as_intf_num = itf;
+            audio->ep_out = ep_addr;
+            audio->ep_out_as_intf_num = itf;
+            audio->ep_out_sz = ((tusb_desc_endpoint_t const *) p_desc)->wMaxPacketSize.size;
+
+#if CFG_TUD_AUDIO_ENABLE_DECODING
+            audiod_parse_for_AS_params(audio, p_desc_parse_for_params, p_desc_end, itf);
 
+            // Reconfigure size of support FIFOs - this is necessary to avoid samples to get split in case of a wrap
+#if CFG_TUD_AUDIO_ENABLE_TYPE_I_DECODING
+            const uint16_t active_fifo_depth = (audio->rx_supp_ff_sz_max / audio->n_bytes_per_sampe_rx) * audio->n_bytes_per_sampe_rx;
+            for (uint8_t cnt = 0; cnt < audio->n_rx_supp_ff; cnt++)
+            {
+              tu_fifo_config(&audio->rx_supp_ff[cnt], audio->rx_supp_ff[cnt].buffer, active_fifo_depth, 1, true);
+            }
+            audio->n_ff_used_rx = audio->n_channels_rx / audio->n_channels_per_ff_rx;
+            TU_ASSERT( audio->n_ff_used_rx <= audio->n_rx_supp_ff );
+#endif
+#endif
             // Invoke callback
             if (tud_audio_set_itf_cb) TU_VERIFY(tud_audio_set_itf_cb(rhport, p_request));
 
             // Prepare for incoming data
-            TU_ASSERT(usbd_edpt_xfer(rhport, ep_addr, _audiod_itf[idxDriver].epout_buf, CFG_TUD_AUDIO_EPSIZE_OUT), false);
+#if USE_LINEAR_BUFFER_RX
+            TU_VERIFY(usbd_edpt_xfer(rhport, audio->ep_out, audio->lin_buf_out, audio->ep_out_sz), false);
+#else
+            TU_VERIFY(usbd_edpt_iso_xfer(rhport, audio->ep_out, &audio->ep_out_ff, audio->ep_out_sz), false);
+#endif
           }
 
 #if CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP
           if (tu_edpt_dir(ep_addr) == TUSB_DIR_IN && ((tusb_desc_endpoint_t const *) p_desc)->bmAttributes.usage == 1)   // Check if usage is explicit data feedback
           {
-            _audiod_itf[idxDriver].ep_fb = ep_addr;
+            audio->ep_fb = ep_addr;
 
             // Invoke callback
             if (tud_audio_set_itf_cb) TU_VERIFY(tud_audio_set_itf_cb(rhport, p_request));
           }
 #endif
+#endif // CFG_TUD_AUDIO_ENABLE_EP_OUT
 
-#endif
           foundEPs += 1;
         }
         p_desc = tu_desc_next(p_desc);
@@ -1166,7 +1787,7 @@ static bool audiod_control_request(uint8_t rhport, tusb_control_request_t const
     }
 
     // If we end here, the received request is a set request - we schedule a receive for the data stage and return true here. We handle the rest later in audiod_control_complete() once the data stage was finished
-    TU_VERIFY(tud_control_xfer(rhport, p_request, _audiod_itf[idxDriver].ctrl_buf, CFG_TUD_AUDIO_CTRL_BUF_SIZE));
+    TU_VERIFY(tud_control_xfer(rhport, p_request, _audiod_itf[idxDriver].ctrl_buf, _audiod_itf[idxDriver].ctrl_buf_sz));
     return true;
   }
 
@@ -1208,21 +1829,15 @@ bool audiod_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t result, uint3
       // In case there is nothing to send we have to return a NAK - this is taken care of by PHY ???
       // In case of an erroneous transmission a retransmission is conducted - this is taken care of by PHY ???
 
-      // Load new data
-      uint16 *n_bytes_copied;
-      TU_VERIFY(audio_int_ctr_done_cb(rhport, &_audiod_itf[idxDriver], n_bytes_copied));
+      // I assume here, that things above are handled by PHY
+      // All transmission is done - what remains to do is to inform job was completed
 
-      if (*n_bytes_copied == 0 && xferred_bytes && (0 == (xferred_bytes % CFG_TUD_AUDIO_INT_CTR_EPSIZE_IN)))
-      {
-        // There is no data left to send, a ZLP should be sent if
-        // xferred_bytes is multiple of EP size and not zero
-        return usbd_edpt_xfer(rhport, ep_addr, NULL, 0);
-      }
+      if (tud_audio_int_ctr_done_cb) TU_VERIFY(tud_audio_int_ctr_done_cb(rhport, (uint16_t) xferred_bytes));
     }
 
 #endif
 
-#if CFG_TUD_AUDIO_EPSIZE_IN
+#if CFG_TUD_AUDIO_ENABLE_EP_IN
 
     // Data transmission of audio packet finished
     if (_audiod_itf[idxDriver].ep_in == ep_addr)
@@ -1236,25 +1851,19 @@ bool audiod_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t result, uint3
       // This is the only place where we can fill something into the EPs buffer!
 
       // Load new data
-      uint16_t n_bytes_copied;
-      TU_VERIFY(audiod_tx_done_cb(rhport, &_audiod_itf[idxDriver], &n_bytes_copied));
+      TU_VERIFY(audiod_tx_done_cb(rhport, &_audiod_itf[idxDriver]));
 
       // Transmission of ZLP is done by audiod_tx_done_cb()
       return true;
     }
 #endif
 
-#if CFG_TUD_AUDIO_EPSIZE_OUT
+#if CFG_TUD_AUDIO_ENABLE_EP_OUT
 
     // New audio packet received
     if (_audiod_itf[idxDriver].ep_out == ep_addr)
     {
-      // Save into buffer - do whatever has to be done
-      TU_VERIFY(audio_rx_done_cb(rhport, &_audiod_itf[idxDriver], _audiod_itf[idxDriver].epout_buf, xferred_bytes));
-
-      // prepare for next transmission
-      TU_ASSERT(usbd_edpt_xfer(rhport, ep_addr, _audiod_itf[idxDriver].epout_buf, CFG_TUD_AUDIO_EPSIZE_OUT), false);
-
+      TU_VERIFY(audiod_rx_done_cb(rhport, &_audiod_itf[idxDriver], (uint16_t) xferred_bytes));
       return true;
     }
 
@@ -1265,14 +1874,14 @@ bool audiod_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t result, uint3
     {
       if (tud_audio_fb_done_cb) TU_VERIFY(tud_audio_fb_done_cb(rhport));
 
-      return audio_fb_send(rhport, &_audiod_itf[idxDriver]);
+      // Schedule next transmission - value is changed bytud_audio_n_fb_set() in the meantime or the old value gets sent
+      return audiod_fb_send(rhport, &_audiod_itf[idxDriver]);
     }
 #endif
 #endif
   }
 
   return false;
-
 }
 
 bool tud_audio_buffer_and_schedule_control_xfer(uint8_t rhport, tusb_control_request_t const * p_request, void* data, uint16_t len)
@@ -1317,7 +1926,7 @@ bool tud_audio_buffer_and_schedule_control_xfer(uint8_t rhport, tusb_control_req
   }
 
   // Crop length
-  if (len > CFG_TUD_AUDIO_CTRL_BUF_SIZE) len = CFG_TUD_AUDIO_CTRL_BUF_SIZE;
+  if (len > _audiod_itf[idxDriver].ctrl_buf_sz) len = _audiod_itf[idxDriver].ctrl_buf_sz;
 
   // Copy into buffer
   memcpy((void *)_audiod_itf[idxDriver].ctrl_buf, data, (size_t)len);
@@ -1338,7 +1947,7 @@ static bool audiod_get_AS_interface_index(uint8_t itf, uint8_t *idxDriver, uint8
     if (_audiod_itf[i].p_desc)
     {
       // Get pointer at end
-      uint8_t const *p_desc_end = _audiod_itf[i].p_desc + tud_audio_desc_lengths[i] - TUD_AUDIO_DESC_IAD_LEN;
+      uint8_t const *p_desc_end = _audiod_itf[i].p_desc + _audiod_itf[i].desc_length - TUD_AUDIO_DESC_IAD_LEN;
 
       // Advance past AC descriptors
       uint8_t const *p_desc = tu_desc_next(_audiod_itf[i].p_desc);
@@ -1403,7 +2012,7 @@ static bool audiod_verify_itf_exists(uint8_t itf, uint8_t *idxDriver)
     {
       // Get pointer at beginning and end
       uint8_t const *p_desc = _audiod_itf[i].p_desc;
-      uint8_t const *p_desc_end = _audiod_itf[i].p_desc + tud_audio_desc_lengths[i] - TUD_AUDIO_DESC_IAD_LEN;
+      uint8_t const *p_desc_end = _audiod_itf[i].p_desc + _audiod_itf[i].desc_length - TUD_AUDIO_DESC_IAD_LEN;
 
       while (p_desc < p_desc_end)
       {
@@ -1427,7 +2036,7 @@ static bool audiod_verify_ep_exists(uint8_t ep, uint8_t *idxDriver)
     if (_audiod_itf[i].p_desc)
     {
       // Get pointer at end
-      uint8_t const *p_desc_end = _audiod_itf[i].p_desc + tud_audio_desc_lengths[i];
+      uint8_t const *p_desc_end = _audiod_itf[i].p_desc + _audiod_itf[i].desc_length;
 
       // Advance past AC descriptors - EP we look for are streaming EPs
       uint8_t const *p_desc = tu_desc_next(_audiod_itf[i].p_desc);
@@ -1447,15 +2056,125 @@ static bool audiod_verify_ep_exists(uint8_t ep, uint8_t *idxDriver)
   return false;
 }
 
+#if CFG_TUD_AUDIO_ENABLE_ENCODING || CFG_TUD_AUDIO_ENABLE_DECODING
+// p_desc points to the AS interface of alternate setting zero
+// itf is the interface number of the corresponding interface - we check if the interface belongs to EP in or EP out to see if it is a TX or RX parameter
+// Currently, only AS interfaces with an EP (in or out) are supposed to be parsed for!
+static void audiod_parse_for_AS_params(audiod_interface_t* audio, uint8_t const * p_desc, uint8_t const * p_desc_end, uint8_t const itf)
+{
+  p_desc = tu_desc_next(p_desc);    // Exclude standard AS interface descriptor of current alternate interface descriptor
+
+  while (p_desc < p_desc_end)
+  {
+    // Abort if follow up descriptor is a new standard interface descriptor - indicates the last AS descriptor was already finished
+    if (tu_desc_type(p_desc) == TUSB_DESC_INTERFACE) break;
+
+    // Look for a Class-Specific AS Interface Descriptor(4.9.2) to verify format type and format and also to get number of physical channels
+    if (tu_desc_type(p_desc) == TUSB_DESC_CS_INTERFACE && tu_desc_subtype(p_desc) == AUDIO_CS_AS_INTERFACE_AS_GENERAL)
+    {
+#if CFG_TUD_AUDIO_ENABLE_EP_IN && CFG_TUD_AUDIO_ENABLE_EP_OUT
+      if (itf != audio->ep_in_as_intf_num && itf != audio->ep_out_as_intf_num) break;           // Abort loop, this interface has no EP, this driver does not support this currently
+#endif
+#if CFG_TUD_AUDIO_ENABLE_EP_IN && !CFG_TUD_AUDIO_ENABLE_EP_OUT
+      if (itf != audio->ep_in_as_intf_num) break;
+#endif
+#if !CFG_TUD_AUDIO_ENABLE_EP_IN && CFG_TUD_AUDIO_ENABLE_EP_OUT
+      if (itf != audio->ep_out_as_intf_num) break;
+#endif
+
+#if CFG_TUD_AUDIO_ENABLE_EP_IN
+      if (itf == audio->ep_in_as_intf_num)
+      {
+        audio->n_channels_tx = ((audio_desc_cs_as_interface_t const * )p_desc)->bNrChannels;
+        audio->format_type_tx = ((audio_desc_cs_as_interface_t const * )p_desc)->bFormatType;
+
+#if CFG_TUD_AUDIO_ENABLE_TYPE_I_ENCODING
+        audio->format_type_I_tx = ((audio_desc_cs_as_interface_t const * )p_desc)->bmFormats;
+#endif
+      }
+#endif
+
+#if CFG_TUD_AUDIO_ENABLE_EP_OUT
+      if (itf == audio->ep_out_as_intf_num)
+      {
+        audio->n_channels_rx = ((audio_desc_cs_as_interface_t const * )p_desc)->bNrChannels;
+        audio->format_type_rx = ((audio_desc_cs_as_interface_t const * )p_desc)->bFormatType;
+#if CFG_TUD_AUDIO_ENABLE_TYPE_I_DECODING
+        audio->format_type_I_rx = ((audio_desc_cs_as_interface_t const * )p_desc)->bmFormats;
+#endif
+      }
+#endif
+    }
+
+    // Look for a Type I Format Type Descriptor(2.3.1.6 - Audio Formats)
+#if CFG_TUD_AUDIO_ENABLE_TYPE_I_ENCODING || CFG_TUD_AUDIO_ENABLE_TYPE_I_DECODING
+    if (tu_desc_type(p_desc) == TUSB_DESC_CS_INTERFACE && tu_desc_subtype(p_desc) == AUDIO_CS_AS_INTERFACE_FORMAT_TYPE && ((audio_desc_type_I_format_t const * )p_desc)->bFormatType == AUDIO_FORMAT_TYPE_I)
+    {
+#if CFG_TUD_AUDIO_ENABLE_EP_IN && CFG_TUD_AUDIO_ENABLE_EP_OUT
+      if (itf != audio->ep_in_as_intf_num && itf != audio->ep_out_as_intf_num) break;           // Abort loop, this interface has no EP, this driver does not support this currently
+#endif
+#if CFG_TUD_AUDIO_ENABLE_EP_IN && !CFG_TUD_AUDIO_ENABLE_EP_OUT
+      if (itf != audio->ep_in_as_intf_num) break;
+#endif
+#if !CFG_TUD_AUDIO_ENABLE_EP_IN && CFG_TUD_AUDIO_ENABLE_EP_OUT
+      if (itf != audio->ep_out_as_intf_num) break;
+#endif
+
+#if CFG_TUD_AUDIO_ENABLE_EP_IN
+      if (itf == audio->ep_in_as_intf_num)
+      {
+        audio->n_bytes_per_sampe_tx = ((audio_desc_type_I_format_t const * )p_desc)->bSubslotSize;
+      }
+#endif
+
+#if CFG_TUD_AUDIO_ENABLE_EP_OUT
+      if (itf == audio->ep_out_as_intf_num)
+      {
+        audio->n_bytes_per_sampe_rx = ((audio_desc_type_I_format_t const * )p_desc)->bSubslotSize;
+      }
+#endif
+    }
+#endif
+
+    // Other format types are not supported yet
+
+    p_desc = tu_desc_next(p_desc);
+  }
+}
+#endif
+
 #if CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP
-bool tud_audio_fb_set(uint8_t rhport, uint32_t feedback)
+
+// Input value feedback has to be in 16.16 format - the format will be converted according to speed settings automatically
+bool tud_audio_n_fb_set(uint8_t itf, uint32_t feedback)
 {
-  audiod_interface_t *audio = &_audiod_itf[0];
+  TU_VERIFY(itf < CFG_TUD_AUDIO && _audiod_itf[itf].p_desc != NULL);
 
-  audio->fb_val = feedback;
-  TU_VERIFY(!usbd_edpt_busy(rhport, audio->ep_fb), true);
+  // Format the feedback value
+  if (_audiod_itf[itf].rhport == 0)
+  {
+    uint8_t * fb = (uint8_t *) &_audiod_itf[itf].fb_val;
 
-  return audio_fb_send(rhport, audio);
+    // For FS format is 10.14
+    *(fb++) = (feedback >> 2) & 0xFF;
+    *(fb++) = (feedback >> 10) & 0xFF;
+    *(fb++) = (feedback >> 18) & 0xFF;
+    // 4th byte is needed to work correctly with MS Windows
+    *fb = 0;
+  }
+  else
+  {
+    // For HS format is 16.16 as originally demanded
+    _audiod_itf[itf].fb_val = feedback;
+  }
+
+  // Schedule a transmit with the new value if EP is not busy - this triggers repetitive scheduling of the feedback value
+  if (!usbd_edpt_busy(_audiod_itf[itf].rhport, _audiod_itf[itf].ep_fb))
+  {
+    return audiod_fb_send(_audiod_itf[itf].rhport, &_audiod_itf[itf]);
+  }
+
+  return true;
 }
 #endif
 
diff --git a/src/class/audio/audio_device.h b/src/class/audio/audio_device.h
index 5061501ce..f91540b64 100644
--- a/src/class/audio/audio_device.h
+++ b/src/class/audio/audio_device.h
@@ -38,116 +38,306 @@
 // Class Driver Configuration
 //--------------------------------------------------------------------+
 
-// Number of Standard AS Interface Descriptors (4.9.1) defined per audio function - this is required to be able to remember the current alternate settings of these interfaces - We restrict us here to have a constant number for all audio functions (which means this has to be the maximum number of AS interfaces an audio function has and a second audio function with less AS interfaces just waste a few bytes)
-#ifndef CFG_TUD_AUDIO_N_AS_INT
-#define CFG_TUD_AUDIO_N_AS_INT  0
+// All sizes are in bytes!
+
+#ifndef CFG_TUD_AUDIO_FUNC_1_DESC_LEN
+#error You must tell the driver the length of the audio function descriptor including IAD descriptor
+#endif
+#if CFG_TUD_AUDIO > 1
+#ifndef CFG_TUD_AUDIO_FUNC_2_DESC_LEN
+#error You must tell the driver the length of the audio function descriptor including IAD descriptor
+#endif
+#endif
+#if CFG_TUD_AUDIO > 2
+#ifndef CFG_TUD_AUDIO_FUNC_3_DESC_LEN
+#error You must tell the driver the length of the audio function descriptor including IAD descriptor
+#endif
+#endif
+
+// Number of Standard AS Interface Descriptors (4.9.1) defined per audio function - this is required to be able to remember the current alternate settings of these interfaces
+#ifndef CFG_TUD_AUDIO_FUNC_1_N_AS_INT
+#error You must tell the driver the number of Standard AS Interface Descriptors you have defined in the audio function descriptor!
+#endif
+#if CFG_TUD_AUDIO > 1
+#ifndef CFG_TUD_AUDIO_FUNC_2_N_AS_INT
+#error You must tell the driver the number of Standard AS Interface Descriptors you have defined in the audio function descriptor!
+#endif
+#endif
+#if CFG_TUD_AUDIO > 2
+#ifndef CFG_TUD_AUDIO_FUNC_3_N_AS_INT
+#error You must tell the driver the number of Standard AS Interface Descriptors you have defined in the audio function descriptor!
+#endif
 #endif
 
 // Size of control buffer used to receive and send control messages via EP0 - has to be big enough to hold your biggest request structure e.g. range requests with multiple intervals defined or cluster descriptors
-#ifndef CFG_TUD_AUDIO_CTRL_BUF_SIZE
+#ifndef CFG_TUD_AUDIO_FUNC_1_CTRL_BUF_SZ
 #error You must define an audio class control request buffer size!
 #endif
 
-// Use of TX/RX FIFOs - If sizes are not zero, audio.c implements FIFOs for RX and TX (whatever defined).
-// For RX: the input stream gets decoded into its corresponding channels, where for each channel a FIFO is setup to hold its data -> see: audio_rx_done_cb().
-// For TX: the output stream is composed from CFG_TUD_AUDIO_N_CHANNELS_TX channels, where for each channel a FIFO is defined.
-// Further, it implements encoding and decoding of the individual channels (parameterized by the defines below).
-// If you don't use the FIFOs you need to handle encoding and decoding on your own in audio_rx_done_cb() and audio_tx_done_cb(). This, however, allows for optimizations.
+#if CFG_TUD_AUDIO > 1
+#ifndef CFG_TUD_AUDIO_FUNC_2_CTRL_BUF_SZ
+#error You must define an audio class control request buffer size!
+#endif
+#endif
 
-#ifndef CFG_TUD_AUDIO_TX_FIFO_SIZE
-#define CFG_TUD_AUDIO_TX_FIFO_SIZE  0                           // Buffer size per channel
+#if CFG_TUD_AUDIO > 2
+#ifndef CFG_TUD_AUDIO_FUNC_3_CTRL_BUF_SZ
+#error You must define an audio class control request buffer size!
+#endif
 #endif
 
-#ifndef CFG_TUD_AUDIO_RX_FIFO_SIZE
-#define CFG_TUD_AUDIO_RX_FIFO_SIZE  0                           // Buffer size per channel
+// End point sizes IN BYTES - Limits: Full Speed <= 1023, High Speed <= 1024
+#ifndef CFG_TUD_AUDIO_ENABLE_EP_IN
+#define CFG_TUD_AUDIO_ENABLE_EP_IN 0   // TX
 #endif
 
-// End point sizes - Limits: Full Speed <= 1023, High Speed <= 1024
-#ifndef CFG_TUD_AUDIO_EPSIZE_IN
-#define CFG_TUD_AUDIO_EPSIZE_IN 0   // TX
+#ifndef CFG_TUD_AUDIO_ENABLE_EP_OUT
+#define CFG_TUD_AUDIO_ENABLE_EP_OUT 0  // RX
 #endif
 
-#ifndef CFG_TUD_AUDIO_EPSIZE_OUT
-#define CFG_TUD_AUDIO_EPSIZE_OUT 0  // RX
+// Maximum EP sizes for all alternate AS interface settings - used for checks and buffer allocation
+#if CFG_TUD_AUDIO_ENABLE_EP_IN
+#ifndef CFG_TUD_AUDIO_FUNC_1_EP_IN_SZ_MAX
+#error You must tell the driver the biggest EP IN size!
+#endif
+#if CFG_TUD_AUDIO > 1
+#ifndef CFG_TUD_AUDIO_FUNC_2_EP_IN_SZ_MAX
+#error You must tell the driver the biggest EP IN size!
+#endif
 #endif
+#if CFG_TUD_AUDIO > 2
+#ifndef CFG_TUD_AUDIO_FUNC_3_EP_IN_SZ_MAX
+#error You must tell the driver the biggest EP IN size!
+#endif
+#endif
+#endif // CFG_TUD_AUDIO_ENABLE_EP_IN
 
-#ifndef CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP
-#define CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP 0                      // Feedback
+#if CFG_TUD_AUDIO_ENABLE_EP_OUT
+#ifndef CFG_TUD_AUDIO_FUNC_1_EP_OUT_SZ_MAX
+#error You must tell the driver the biggest EP OUT size!
 #endif
+#if CFG_TUD_AUDIO > 1
+#ifndef CFG_TUD_AUDIO_FUNC_2_EP_OUT_SZ_MAX
+#error You must tell the driver the biggest EP OUT size!
+#endif
+#endif
+#if CFG_TUD_AUDIO > 2
+#ifndef CFG_TUD_AUDIO_FUNC_3_EP_OUT_SZ_MAX
+#error You must tell the driver the biggest EP OUT size!
+#endif
+#endif
+#endif // CFG_TUD_AUDIO_ENABLE_EP_OUT
 
-#ifndef CFG_TUD_AUDIO_INT_CTR_EPSIZE_IN
-#define CFG_TUD_AUDIO_INT_CTR_EPSIZE_IN 0                       // Audio interrupt control
+// Software EP FIFO buffer sizes - must be >= max EP SIZEs!
+#ifndef CFG_TUD_AUDIO_FUNC_1_EP_IN_SW_BUF_SZ
+#define CFG_TUD_AUDIO_FUNC_1_EP_IN_SW_BUF_SZ                0
+#endif
+#ifndef CFG_TUD_AUDIO_FUNC_2_EP_IN_SW_BUF_SZ
+#define CFG_TUD_AUDIO_FUNC_2_EP_IN_SW_BUF_SZ                0
+#endif
+#ifndef CFG_TUD_AUDIO_FUNC_3_EP_IN_SW_BUF_SZ
+#define CFG_TUD_AUDIO_FUNC_3_EP_IN_SW_BUF_SZ                0
 #endif
 
-#if CFG_TUD_AUDIO_INT_CTR_EPSIZE_IN
-#ifndef CFG_TUD_AUDIO_INT_CTR_BUFSIZE
-#define CFG_TUD_AUDIO_INT_CTR_BUFSIZE   6                       // Buffer size of audio control interrupt EP - 6 Bytes according to UAC 2 specification (p. 74)
+#ifndef CFG_TUD_AUDIO_FUNC_1_EP_OUT_SW_BUF_SZ
+#define CFG_TUD_AUDIO_FUNC_1_EP_OUT_SW_BUF_SZ               0
+#endif
+#ifndef CFG_TUD_AUDIO_FUNC_2_EP_OUT_SW_BUF_SZ
+#define CFG_TUD_AUDIO_FUNC_2_EP_OUT_SW_BUF_SZ               0
 #endif
+#ifndef CFG_TUD_AUDIO_FUNC_3_EP_OUT_SW_BUF_SZ
+#define CFG_TUD_AUDIO_FUNC_3_EP_OUT_SW_BUF_SZ               0
 #endif
 
-#ifndef CFG_TUD_AUDIO_N_CHANNELS_TX
-#define CFG_TUD_AUDIO_N_CHANNELS_TX                     1
+#if CFG_TUD_AUDIO_ENABLE_EP_IN
+#if CFG_TUD_AUDIO_FUNC_1_EP_IN_SW_BUF_SZ < CFG_TUD_AUDIO_FUNC_1_EP_IN_SZ_MAX
+#error EP software buffer size MUST BE at least as big as maximum EP size
 #endif
 
-#ifndef CFG_TUD_AUDIO_N_CHANNELS_RX
-#define CFG_TUD_AUDIO_N_CHANNELS_RX                     1
+#if CFG_TUD_AUDIO > 1
+#if CFG_TUD_AUDIO_FUNC_2_EP_IN_SW_BUF_SZ < CFG_TUD_AUDIO_FUNC_2_EP_IN_SZ_MAX
+#error EP software buffer size MUST BE at least as big as maximum EP size
+#endif
 #endif
 
-// Audio data format types
-#ifndef CFG_TUD_AUDIO_FORMAT_TYPE_TX
-#define CFG_TUD_AUDIO_FORMAT_TYPE_TX                AUDIO_FORMAT_TYPE_UNDEFINED     // If this option is used, an encoding function has to be implemented in audio_device.c
+#if CFG_TUD_AUDIO > 2
+#if CFG_TUD_AUDIO_FUNC_3_EP_IN_SW_BUF_SZ < CFG_TUD_AUDIO_FUNC_3_EP_IN_SZ_MAX
+#error EP software buffer size MUST BE at least as big as maximum EP size
+#endif
+#endif
 #endif
 
-#ifndef CFG_TUD_AUDIO_FORMAT_TYPE_RX
-#define CFG_TUD_AUDIO_FORMAT_TYPE_RX                AUDIO_FORMAT_TYPE_UNDEFINED     // If this option is used, a decoding function has to be implemented in audio_device.c
+#if CFG_TUD_AUDIO_ENABLE_EP_OUT
+#if CFG_TUD_AUDIO_FUNC_1_EP_OUT_SW_BUF_SZ < CFG_TUD_AUDIO_FUNC_1_EP_OUT_SZ_MAX
+#error EP software buffer size MUST BE at least as big as maximum EP size
 #endif
 
-// Audio data format type I specifications
-#if CFG_TUD_AUDIO_FORMAT_TYPE_TX == AUDIO_FORMAT_TYPE_I
+#if CFG_TUD_AUDIO > 1
+#if CFG_TUD_AUDIO_FUNC_2_EP_OUT_SW_BUF_SZ < CFG_TUD_AUDIO_FUNC_2_EP_OUT_SZ_MAX
+#error EP software buffer size MUST BE at least as big as maximum EP size
+#endif
+#endif
 
-// Type definitions - for possible formats see: audio_data_format_type_I_t and further in UAC2 specifications.
-#ifndef CFG_TUD_AUDIO_FORMAT_TYPE_I_TX
-#define CFG_TUD_AUDIO_FORMAT_TYPE_I_TX              AUDIO_DATA_FORMAT_TYPE_I_PCM
+#if CFG_TUD_AUDIO > 2
+#if CFG_TUD_AUDIO_FUNC_3_EP_OUT_SW_BUF_SZ < CFG_TUD_AUDIO_FUNC_3_EP_OUT_SZ_MAX
+#error EP software buffer size MUST BE at least as big as maximum EP size
+#endif
+#endif
 #endif
 
-#ifndef CFG_TUD_AUDIO_N_BYTES_PER_SAMPLE_TX             // bSubslotSize
-#define CFG_TUD_AUDIO_N_BYTES_PER_SAMPLE_TX             1
+// Enable/disable feedback EP (required for asynchronous RX applications)
+#ifndef CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP
+#define CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP                    0                             // Feedback - 0 or 1
 #endif
 
-#ifndef CFG_TUD_AUDIO_TX_ITEMSIZE
-#if CFG_TUD_AUDIO_N_BYTES_PER_SAMPLE_TX == 1
-#define CFG_TUD_AUDIO_TX_ITEMSIZE 1
-#elif CFG_TUD_AUDIO_N_BYTES_PER_SAMPLE_TX == 2
-#define CFG_TUD_AUDIO_TX_ITEMSIZE 2
-#else
-#define CFG_TUD_AUDIO_TX_ITEMSIZE 4
+// Audio interrupt control EP size - disabled if 0
+#ifndef CFG_TUD_AUDIO_INT_CTR_EPSIZE_IN
+#define CFG_TUD_AUDIO_INT_CTR_EPSIZE_IN                     0                             // Audio interrupt control - if required - 6 Bytes according to UAC 2 specification (p. 74)
 #endif
+
+#ifndef CFG_TUD_AUDIO_INT_CTR_EP_IN_SW_BUFFER_SIZE
+#define CFG_TUD_AUDIO_INT_CTR_EP_IN_SW_BUFFER_SIZE          6                             // Buffer size of audio control interrupt EP - 6 Bytes according to UAC 2 specification (p. 74)
 #endif
 
-#if CFG_TUD_AUDIO_TX_ITEMSIZE < CFG_TUD_AUDIO_N_BYTES_PER_SAMPLE_TX
-#error FIFO element size (ITEMSIZE) must not be smaller then sample size
+// Use software encoding/decoding
+
+// The software coding feature of the driver is not mandatory. It is useful if, for instance, you have two I2S streams which need to be interleaved
+// into a single PCM stream as SAMPLE_1 | SAMPLE_2 | SAMPLE_3 | SAMPLE_4.
+//
+// Currently, only PCM type I encoding/decoding is supported!
+//
+// If the coding feature is to be used, support FIFOs need to be configured. Their sizes and numbers are defined below.
+
+// Encoding/decoding is done in software and thus time consuming. If you can encode/decode your stream more efficiently do not use the
+// support FIFOs but write/read directly into/from the EP_X_SW_BUFFER_FIFOs using
+// - tud_audio_n_write() or
+// - tud_audio_n_read().
+// To write/read to/from the support FIFOs use
+// - tud_audio_n_write_support_ff() or
+// - tud_audio_n_read_support_ff().
+//
+// The encoding/decoding format type done is defined below.
+//
+// The encoding/decoding starts when the private callback functions
+// - audio_tx_done_cb()
+// - audio_rx_done_cb()
+// are invoked. If support FIFOs are used, the corresponding encoding/decoding functions are called from there.
+// Once encoding/decoding is done the result is put directly into the EP_X_SW_BUFFER_FIFOs. You can use the public callback functions
+// - tud_audio_tx_done_pre_load_cb() or tud_audio_tx_done_post_load_cb()
+// - tud_audio_rx_done_pre_read_cb() or tud_audio_rx_done_post_read_cb()
+// if you want to get informed what happened.
+//
+// If you don't use the support FIFOs you may use the public callback functions
+// - tud_audio_tx_done_pre_load_cb() or tud_audio_tx_done_post_load_cb()
+// - tud_audio_rx_done_pre_read_cb() or tud_audio_rx_done_post_read_cb()
+// to write/read from/into the EP_X_SW_BUFFER_FIFOs at the right time.
+//
+// If you need a different encoding which is not support so far implement it in the
+// - audio_tx_done_cb()
+// - audio_rx_done_cb()
+// functions.
+
+// Enable encoding/decodings - for these to work, support FIFOs need to be setup in appropriate numbers and size
+// The actual coding parameters of active AS alternate interface is parsed from the descriptors
+
+// The item size of the FIFO is always fixed to one i.e. bytes! Furthermore, the actively used FIFO depth is reconfigured such that the depth is a multiple of the current sample size in order to avoid samples to get split up in case of a wrap in the FIFO ring buffer (depth = (max_depth / sampe_sz) * sampe_sz)!
+// This is important to remind in case you use DMAs! If the sample sizes changes, the DMA MUST BE RECONFIGURED just like the FIFOs for a different depth!!!
+
+// For PCM encoding/decoding
+
+#ifndef CFG_TUD_AUDIO_ENABLE_ENCODING
+#define CFG_TUD_AUDIO_ENABLE_ENCODING                       0
+#endif
+
+#ifndef CFG_TUD_AUDIO_ENABLE_DECODING
+#define CFG_TUD_AUDIO_ENABLE_DECODING                       0
+#endif
+
+// This enabling allows to save the current coding parameters e.g. # of bytes per sample etc. - TYPE_I includes common PCM encoding
+#ifndef CFG_TUD_AUDIO_ENABLE_TYPE_I_ENCODING
+#define CFG_TUD_AUDIO_ENABLE_TYPE_I_ENCODING                0
+#endif
+
+#ifndef CFG_TUD_AUDIO_ENABLE_TYPE_I_DECODING
+#define CFG_TUD_AUDIO_ENABLE_TYPE_I_DECODING                0
+#endif
+
+// Type I Coding parameters not given within UAC2 descriptors
+// It would be possible to allow for a more flexible setting and not fix this parameter as done below. However, this is most often not needed and kept for later if really necessary. The more flexible setting could be implemented within set_interface(), however, how the values are saved per alternate setting is to be determined!
+#if CFG_TUD_AUDIO_ENABLE_EP_IN && CFG_TUD_AUDIO_ENABLE_ENCODING && CFG_TUD_AUDIO_ENABLE_TYPE_I_ENCODING
+#ifndef CFG_TUD_AUDIO_FUNC_1_CHANNEL_PER_FIFO_TX
+#error You must tell the driver the number of channels per FIFO for the interleaved encoding! E.g. for an I2S interface having two channels, CHANNEL_PER_FIFO = 2 as the I2S stream having two channels is usually saved within one FIFO
+#endif
+#if CFG_TUD_AUDIO > 1
+#ifndef CFG_TUD_AUDIO_FUNC_2_CHANNEL_PER_FIFO_TX
+#error You must tell the driver the number of channels per FIFO for the interleaved encoding! E.g. for an I2S interface having two channels, CHANNEL_PER_FIFO = 2 as the I2S stream having two channels is usually saved within one FIFO
+#endif
+#endif
+#if CFG_TUD_AUDIO > 2
+#ifndef CFG_TUD_AUDIO_FUNC_3_CHANNEL_PER_FIFO_TX
+#error You must tell the driver the number of channels per FIFO for the interleaved encoding! E.g. for an I2S interface having two channels, CHANNEL_PER_FIFO = 2 as the I2S stream having two channels is usually saved within one FIFO
+#endif
+#endif
 #endif
 
+#if CFG_TUD_AUDIO_ENABLE_EP_OUT && CFG_TUD_AUDIO_ENABLE_DECODING && CFG_TUD_AUDIO_ENABLE_TYPE_I_DECODING
+#ifndef CFG_TUD_AUDIO_FUNC_1_CHANNEL_PER_FIFO_RX
+#error You must tell the driver the number of channels per FIFO for the interleaved encoding! E.g. for an I2S interface having two channels, CHANNEL_PER_FIFO = 2 as the I2S stream having two channels is usually saved within one FIFO
+#endif
+#if CFG_TUD_AUDIO > 1
+#ifndef CFG_TUD_AUDIO_FUNC_2_CHANNEL_PER_FIFO_RX
+#error You must tell the driver the number of channels per FIFO for the interleaved encoding! E.g. for an I2S interface having two channels, CHANNEL_PER_FIFO = 2 as the I2S stream having two channels is usually saved within one FIFO
+#endif
+#endif
+#if CFG_TUD_AUDIO > 2
+#ifndef CFG_TUD_AUDIO_FUNC_3_CHANNEL_PER_FIFO_RX
+#error You must tell the driver the number of channels per FIFO for the interleaved encoding! E.g. for an I2S interface having two channels, CHANNEL_PER_FIFO = 2 as the I2S stream having two channels is usually saved within one FIFO
+#endif
+#endif
 #endif
 
-#if CFG_TUD_AUDIO_FORMAT_TYPE_RX == AUDIO_FORMAT_TYPE_I
+// Remaining types not support so far
 
-#ifndef CFG_TUD_AUDIO_FORMAT_TYPE_I_RX
-#define CFG_TUD_AUDIO_FORMAT_TYPE_I_RX              AUDIO_DATA_FORMAT_TYPE_I_PCM
+// Number of support FIFOs to set up - multiple channels can be handled by one FIFO - very common is two channels per FIFO stemming from one I2S interface
+#ifndef CFG_TUD_AUDIO_FUNC_1_N_TX_SUPP_SW_FIFO
+#define CFG_TUD_AUDIO_FUNC_1_N_TX_SUPP_SW_FIFO              0
+#endif
+#ifndef CFG_TUD_AUDIO_FUNC_2_N_TX_SUPP_SW_FIFO
+#define CFG_TUD_AUDIO_FUNC_2_N_TX_SUPP_SW_FIFO              0
+#endif
+#ifndef CFG_TUD_AUDIO_FUNC_3_N_TX_SUPP_SW_FIFO
+#define CFG_TUD_AUDIO_FUNC_3_N_TX_SUPP_SW_FIFO              0
 #endif
 
-#ifndef CFG_TUD_AUDIO_N_BYTES_PER_SAMPLE_RX             // bSubslotSize
-#define CFG_TUD_AUDIO_N_BYTES_PER_SAMPLE_RX             1
+#ifndef CFG_TUD_AUDIO_FUNC_1_N_RX_SUPP_SW_FIFO
+#define CFG_TUD_AUDIO_FUNC_1_N_RX_SUPP_SW_FIFO              0
+#endif
+#ifndef CFG_TUD_AUDIO_FUNC_2_N_RX_SUPP_SW_FIFO
+#define CFG_TUD_AUDIO_FUNC_2_N_RX_SUPP_SW_FIFO              0
+#endif
+#ifndef CFG_TUD_AUDIO_FUNC_3_N_RX_SUPP_SW_FIFO
+#define CFG_TUD_AUDIO_FUNC_3_N_RX_SUPP_SW_FIFO              0
 #endif
 
-#if CFG_TUD_AUDIO_N_BYTES_PER_SAMPLE_RX == 1
-#define CFG_TUD_AUDIO_RX_ITEMSIZE 1
-#elif CFG_TUD_AUDIO_N_BYTES_PER_SAMPLE_RX == 2
-#define CFG_TUD_AUDIO_RX_ITEMSIZE 2
-#else
-#define CFG_TUD_AUDIO_RX_ITEMSIZE 4
+// Size of support FIFOs IN BYTES - if size > 0 there are as many FIFOs set up as CFG_TUD_AUDIO_FUNC_X_N_TX_SUPP_SW_FIFO and CFG_TUD_AUDIO_FUNC_X_N_RX_SUPP_SW_FIFO
+#ifndef CFG_TUD_AUDIO_FUNC_1_TX_SUPP_SW_FIFO_SZ
+#define CFG_TUD_AUDIO_FUNC_1_TX_SUPP_SW_FIFO_SZ             0         // FIFO size - minimum size: ceil(f_s/1000) * max(# of TX channels) / (# of TX support FIFOs) * max(# of bytes per sample)
+#endif
+#ifndef CFG_TUD_AUDIO_FUNC_2_TX_SUPP_SW_FIFO_SZ
+#define CFG_TUD_AUDIO_FUNC_2_TX_SUPP_SW_FIFO_SZ             0
+#endif
+#ifndef CFG_TUD_AUDIO_FUNC_3_TX_SUPP_SW_FIFO_SZ
+#define CFG_TUD_AUDIO_FUNC_3_TX_SUPP_SW_FIFO_SZ             0
 #endif
 
+#ifndef CFG_TUD_AUDIO_FUNC_1_RX_SUPP_SW_FIFO_SZ
+#define CFG_TUD_AUDIO_FUNC_1_RX_SUPP_SW_FIFO_SZ             0         // FIFO size - minimum size: ceil(f_s/1000) * max(# of RX channels) / (# of RX support FIFOs) * max(# of bytes per sample)
+#endif
+#ifndef CFG_TUD_AUDIO_FUNC_2_RX_SUPP_SW_FIFO_SZ
+#define CFG_TUD_AUDIO_FUNC_2_RX_SUPP_SW_FIFO_SZ             0
+#endif
+#ifndef CFG_TUD_AUDIO_FUNC_3_RX_SUPP_SW_FIFO_SZ
+#define CFG_TUD_AUDIO_FUNC_3_RX_SUPP_SW_FIFO_SZ             0
 #endif
 
 //static_assert(sizeof(tud_audio_desc_lengths) != CFG_TUD_AUDIO, "Supply audio function descriptor pack length!");
@@ -170,69 +360,70 @@ extern "C" {
 //--------------------------------------------------------------------+
 bool     tud_audio_n_mounted    (uint8_t itf);
 
-#if CFG_TUD_AUDIO_EPSIZE_OUT && CFG_TUD_AUDIO_RX_FIFO_SIZE
-#if CFG_TUD_AUDIO_RX_FIFO_COUNT > 1
-uint16_t tud_audio_n_available  (uint8_t itf, uint8_t channelId);
-uint16_t tud_audio_n_read       (uint8_t itf, uint8_t channelId, void* buffer, uint16_t bufsize);
-void     tud_audio_n_read_flush (uint8_t itf, uint8_t channelId);
-#else
-uint16_t tud_audio_n_available  (uint8_t itf);
-uint16_t tud_audio_n_read       (uint8_t itf, void* buffer, uint16_t bufsize);
-void     tud_audio_n_read_flush (uint8_t itf);
-#endif
+#if CFG_TUD_AUDIO_ENABLE_EP_OUT && !CFG_TUD_AUDIO_ENABLE_DECODING
+uint16_t tud_audio_n_available                    (uint8_t itf);
+uint16_t tud_audio_n_read                         (uint8_t itf, void* buffer, uint16_t bufsize);
+bool     tud_audio_n_clear_ep_out_ff              (uint8_t itf);                          // Delete all content in the EP OUT FIFO
 #endif
 
-/*  This function is intended for later use once EP buffers (at least for ISO EPs) are implemented as ring buffers
-#if CFG_TUD_AUDIO_EPSIZE_IN && !CFG_TUD_AUDIO_TX_FIFO_SIZE
-uint16_t tud_audio_n_write_ep_in_buffer(uint8_t itf, const void * data, uint16_t len)
+#if CFG_TUD_AUDIO_ENABLE_EP_OUT && CFG_TUD_AUDIO_ENABLE_DECODING
+bool     tud_audio_n_clear_rx_support_ff          (uint8_t itf, uint8_t channelId);       // Delete all content in the support RX FIFOs
+uint16_t tud_audio_n_available_support_ff         (uint8_t itf, uint8_t channelId);
+uint16_t tud_audio_n_read_support_ff              (uint8_t itf, uint8_t channelId, void* buffer, uint16_t bufsize);
 #endif
-*/
 
-#ifndef CFG_TUD_AUDIO_TX_FIFO_COUNT
-#define CFG_TUD_AUDIO_TX_FIFO_COUNT 1
+#if CFG_TUD_AUDIO_ENABLE_EP_IN && !CFG_TUD_AUDIO_ENABLE_ENCODING
+uint16_t tud_audio_n_write                        (uint8_t itf, const void * data, uint16_t len);
+bool     tud_audio_n_clear_ep_in_ff               (uint8_t itf);                          // Delete all content in the EP IN FIFO
 #endif
 
-#if CFG_TUD_AUDIO_EPSIZE_IN && CFG_TUD_AUDIO_TX_FIFO_SIZE
-#if CFG_TUD_AUDIO_TX_FIFO_COUNT > 1
-uint16_t tud_audio_n_write      (uint8_t itf, uint8_t channelId, const void * data, uint16_t len);
-#else
-uint16_t tud_audio_n_write      (uint8_t itf, const void * data, uint16_t len);
-#endif
-uint16_t tud_audio_n_write_flush(uint8_t itf);
+#if CFG_TUD_AUDIO_ENABLE_EP_IN && CFG_TUD_AUDIO_ENABLE_ENCODING
+uint16_t tud_audio_n_flush_tx_support_ff          (uint8_t itf);      // Force all content in the support TX FIFOs to be written into EP SW FIFO
+bool     tud_audio_n_clear_tx_support_ff          (uint8_t itf, uint8_t channelId);
+uint16_t tud_audio_n_write_support_ff             (uint8_t itf, uint8_t channelId, const void * data, uint16_t len);
 #endif
 
-#if CFG_TUD_AUDIO_INT_CTR_EPSIZE_IN > 0
-uint16_t    tud_audio_int_ctr_n_available   (uint8_t itf);
-uint16_t    tud_audio_int_ctr_n_read        (uint8_t itf, void* buffer, uint16_t bufsize);
-void        tud_audio_int_ctr_n_read_flush  (uint8_t itf);
-uint16_t    tud_audio_int_ctr_n_write       (uint8_t itf, uint8_t const* buffer, uint16_t bufsize);
+#if CFG_TUD_AUDIO_INT_CTR_EPSIZE_IN
+uint16_t    tud_audio_int_ctr_n_write             (uint8_t itf, uint8_t const* buffer, uint16_t len);
 #endif
 
 //--------------------------------------------------------------------+
 // Application API (Interface0)
 //--------------------------------------------------------------------+
 
-static inline bool         tud_audio_mounted    (void);
+static inline bool         tud_audio_mounted                (void);
+
+// RX API
 
-#if CFG_TUD_AUDIO_EPSIZE_OUT && CFG_TUD_AUDIO_RX_FIFO_SIZE
-static inline uint16_t     tud_audio_available  (void);
-static inline uint16_t     tud_audio_read       (void* buffer, uint16_t bufsize);
-static inline void         tud_audio_read_flush (void);
+#if CFG_TUD_AUDIO_ENABLE_EP_OUT && !CFG_TUD_AUDIO_ENABLE_DECODING
+static inline uint16_t     tud_audio_available              (void);
+static inline bool         tud_audio_clear_ep_out_ff        (void);                       // Delete all content in the EP OUT FIFO
+static inline uint16_t     tud_audio_read                   (void* buffer, uint16_t bufsize);
 #endif
 
-#if CFG_TUD_AUDIO_EPSIZE_IN && CFG_TUD_AUDIO_TX_FIFO_SIZE
-#if CFG_TUD_AUDIO_TX_FIFO_COUNT > 1
-static inline uint16_t tud_audio_write      (uint8_t channelId, uint8_t const* buffer, uint16_t bufsize);
-#else
-static inline uint16_t tud_audio_write      (uint8_t const* buffer, uint16_t bufsize);
+#if CFG_TUD_AUDIO_ENABLE_EP_OUT && CFG_TUD_AUDIO_ENABLE_DECODING
+static inline bool     tud_audio_clear_rx_support_ff        (uint8_t channelId);
+static inline uint16_t tud_audio_available_support_ff       (uint8_t channelId);
+static inline uint16_t tud_audio_read_support_ff            (uint8_t channelId, void* buffer, uint16_t bufsize);
 #endif
+
+// TX API
+
+#if CFG_TUD_AUDIO_ENABLE_EP_IN && !CFG_TUD_AUDIO_ENABLE_ENCODING
+static inline uint16_t tud_audio_write                      (const void * data, uint16_t len);
+static inline bool 	   tud_audio_clear_ep_in_ff             (void);
 #endif
 
-#if CFG_TUD_AUDIO_INT_CTR_EPSIZE_IN > 0
-static inline uint32_t     tud_audio_int_ctr_available     (void);
-static inline uint32_t     tud_audio_int_ctr_read          (void* buffer, uint32_t bufsize);
-static inline void         tud_audio_int_ctr_read_flush    (void);
-static inline uint32_t     tud_audio_int_ctr_write         (uint8_t const* buffer, uint32_t bufsize);
+#if CFG_TUD_AUDIO_ENABLE_EP_IN && CFG_TUD_AUDIO_ENABLE_ENCODING
+static inline uint16_t tud_audio_flush_tx_support_ff        (void);
+static inline uint16_t tud_audio_clear_tx_support_ff        (uint8_t channelId);
+static inline uint16_t tud_audio_write_support_ff           (uint8_t channelId, const void * data, uint16_t len);
+#endif
+
+// INT CTR API
+
+#if CFG_TUD_AUDIO_INT_CTR_EPSIZE_IN
+static inline uint16_t tud_audio_int_ctr_write              (uint8_t const* buffer, uint16_t len);
 #endif
 
 // Buffer control EP data and schedule a transmit
@@ -247,26 +438,28 @@ bool tud_audio_buffer_and_schedule_control_xfer(uint8_t rhport, tusb_control_req
 // Application Callback API (weak is optional)
 //--------------------------------------------------------------------+
 
-#if CFG_TUD_AUDIO_EPSIZE_IN
+#if CFG_TUD_AUDIO_ENABLE_EP_IN
 TU_ATTR_WEAK bool tud_audio_tx_done_pre_load_cb(uint8_t rhport, uint8_t itf, uint8_t ep_in, uint8_t cur_alt_setting);
 TU_ATTR_WEAK bool tud_audio_tx_done_post_load_cb(uint8_t rhport, uint16_t n_bytes_copied, uint8_t itf, uint8_t ep_in, uint8_t cur_alt_setting);
 #endif
 
-#if CFG_TUD_AUDIO_EPSIZE_OUT
-TU_ATTR_WEAK bool tud_audio_rx_done_cb(uint8_t rhport, uint8_t * buffer, uint16_t bufsize);
+#if CFG_TUD_AUDIO_ENABLE_EP_OUT
+TU_ATTR_WEAK bool tud_audio_rx_done_pre_read_cb(uint8_t rhport, uint16_t n_bytes_received, uint8_t itf, uint8_t ep_out, uint8_t cur_alt_setting);
+TU_ATTR_WEAK bool tud_audio_rx_done_post_read_cb(uint8_t rhport, uint16_t n_bytes_received, uint8_t itf, uint8_t ep_out, uint8_t cur_alt_setting);
 #endif
 
-#if CFG_TUD_AUDIO_EPSIZE_OUT > 0 && CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP
+#if CFG_TUD_AUDIO_ENABLE_EP_OUT && CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP
 TU_ATTR_WEAK bool tud_audio_fb_done_cb(uint8_t rhport);
 // User code should call this function with feedback value in 16.16 format for FS and HS.
 // Value will be corrected for FS to 10.14 format automatically.
 // (see Universal Serial Bus Specification Revision 2.0 5.12.4.2).
 // Feedback value will be sent at FB endpoint interval till it's changed.
-bool tud_audio_fb_set(uint8_t rhport, uint32_t feedback);
+bool tud_audio_n_fb_set(uint8_t itf, uint32_t feedback);
+static inline bool tud_audio_fb_set(uint32_t feedback);
 #endif
 
 #if CFG_TUD_AUDIO_INT_CTR_EPSIZE_IN
-TU_ATTR_WEAK bool tud_audio_int_ctr_done_cb(uint8_t rhport, uint16_t * n_bytes_copied);
+TU_ATTR_WEAK bool tud_audio_int_ctr_done_cb(uint8_t rhport, uint16_t n_bytes_copied);
 #endif
 
 // Invoked when audio set interface request received
@@ -302,93 +495,103 @@ static inline bool tud_audio_mounted(void)
   return tud_audio_n_mounted(0);
 }
 
-#if CFG_TUD_AUDIO_EPSIZE_IN
-#if CFG_TUD_AUDIO_TX_FIFO_SIZE && CFG_TUD_AUDIO_TX_FIFO_COUNT > 1
-static inline uint16_t tud_audio_write (uint8_t channelId, uint8_t const* buffer, uint16_t n_bytes)    // Short version if only one audio function is used
+// RX API
+
+#if CFG_TUD_AUDIO_ENABLE_EP_OUT && !CFG_TUD_AUDIO_ENABLE_DECODING
+
+static inline uint16_t tud_audio_available(void)
 {
-  return tud_audio_n_write(0, channelId, buffer, n_bytes);
+  return tud_audio_n_available(0);
 }
-#else
-static inline uint16_t tud_audio_write (uint8_t const* buffer, uint16_t n_bytes)    // Short version if only one audio function is used
+
+static inline uint16_t tud_audio_read(void* buffer, uint16_t bufsize)
 {
-  return tud_audio_n_write(0, buffer, n_bytes);
+  return tud_audio_n_read(0, buffer, bufsize);
 }
-#endif
 
-static inline uint16_t tud_audio_write_flush (void)    // Short version if only one audio function is used
+static inline bool tud_audio_clear_ep_out_ff(void)
 {
-#if CFG_TUD_AUDIO_TX_FIFO_SIZE
-  return tud_audio_n_write_flush(0);
-#else
-  return 0;
-#endif
+  return tud_audio_n_clear_ep_out_ff(0);
 }
-#endif  // CFG_TUD_AUDIO_EPSIZE_IN && CFG_TUD_AUDIO_TX_FIFO_SIZE
 
-#if CFG_TUD_AUDIO_EPSIZE_OUT && CFG_TUD_AUDIO_RX_FIFO_SIZE
-#if CFG_TUD_AUDIO_RX_FIFO_COUNT > 1
-static inline uint16_t tud_audio_available(uint8_t channelId)
+#endif
+
+#if CFG_TUD_AUDIO_ENABLE_EP_OUT && CFG_TUD_AUDIO_ENABLE_DECODING
+
+static inline bool tud_audio_clear_rx_support_ff(uint8_t channelId)
 {
-  return tud_audio_n_available(0, channelId);
+  return tud_audio_n_clear_rx_support_ff(0, channelId);
 }
 
-static inline uint16_t tud_audio_read(uint8_t channelId, void* buffer, uint16_t bufsize)
+static inline uint16_t tud_audio_available_support_ff(uint8_t channelId)
 {
-  return tud_audio_n_read(0, channelId, buffer, bufsize);
+  return tud_audio_n_available_support_ff(0, channelId);
 }
 
-static inline void tud_audio_read_flush(uint8_t channelId)
+static inline uint16_t tud_audio_read_support_ff(uint8_t channelId, void* buffer, uint16_t bufsize)
 {
-  tud_audio_n_read_flush(0, channelId);
+  return tud_audio_n_read_support_ff(0, channelId, buffer, bufsize);
 }
-#else
-static inline uint16_t tud_audio_available(void)
+
+#endif
+
+// TX API
+
+#if CFG_TUD_AUDIO_ENABLE_EP_IN && !CFG_TUD_AUDIO_ENABLE_ENCODING
+
+static inline uint16_t tud_audio_write(const void * data, uint16_t len)
 {
-  return tud_audio_n_available(0);
+  return tud_audio_n_write(0, data, len);
 }
 
-static inline uint16_t tud_audio_read(void *buffer, uint16_t bufsize)
+static inline bool tud_audio_clear_ep_in_ff(void)
 {
-  return tud_audio_n_read(0, buffer, bufsize);
+  return tud_audio_n_clear_ep_in_ff(0);
 }
 
-static inline void tud_audio_read_flush(void)
+#endif
+
+#if CFG_TUD_AUDIO_ENABLE_EP_IN && CFG_TUD_AUDIO_ENABLE_ENCODING
+
+static inline uint16_t tud_audio_flush_tx_support_ff(void)
 {
-  tud_audio_n_read_flush(0);
+  return tud_audio_n_flush_tx_support_ff(0);
 }
-#endif
-#endif
 
-#if CFG_TUD_AUDIO_INT_CTR_EPSIZE_IN > 0
-static inline uint16_t tud_audio_int_ctr_available(void)
+static inline uint16_t tud_audio_clear_tx_support_ff(uint8_t channelId)
 {
-  return tud_audio_int_ctr_n_available(0);
+  return tud_audio_n_clear_tx_support_ff(0, channelId);
 }
 
-static inline uint16_t tud_audio_int_ctr_read(void* buffer, uint16_t bufsize)
+static inline uint16_t tud_audio_write_support_ff(uint8_t channelId, const void * data, uint16_t len)
 {
-  return tud_audio_int_ctr_n_read(0, buffer, bufsize);
+  return tud_audio_n_write_support_ff(0, channelId, data, len);
 }
 
-static inline void tud_audio_int_ctr_read_flush(void)
+#endif
+
+#if CFG_TUD_AUDIO_INT_CTR_EPSIZE_IN
+static inline uint16_t tud_audio_int_ctr_write(uint8_t const* buffer, uint16_t len)
 {
-  return tud_audio_int_ctr_n_read_flush(0);
+  return tud_audio_int_ctr_n_write(0, buffer, len);
 }
+#endif
 
-static inline uint16_t tud_audio_int_ctr_write(uint8_t const* buffer, uint16_t bufsize)
+#if CFG_TUD_AUDIO_ENABLE_EP_OUT && CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP
+static inline bool tud_audio_fb_set(uint32_t feedback)
 {
-  return tud_audio_int_ctr_n_write(0, buffer, bufsize);
+  return tud_audio_n_fb_set(0, feedback);
 }
 #endif
 
 //--------------------------------------------------------------------+
 // Internal Class Driver API
 //--------------------------------------------------------------------+
-void audiod_init            (void);
-void audiod_reset           (uint8_t rhport);
-uint16_t audiod_open        (uint8_t rhport, tusb_desc_interface_t const * itf_desc, uint16_t max_len);
-bool audiod_control_xfer_cb (uint8_t rhport, uint8_t stage, tusb_control_request_t const * request);
-bool audiod_xfer_cb          (uint8_t rhport, uint8_t edpt_addr, xfer_result_t result, uint32_t xferred_bytes);
+void     audiod_init           (void);
+void     audiod_reset          (uint8_t rhport);
+uint16_t audiod_open           (uint8_t rhport, tusb_desc_interface_t const * itf_desc, uint16_t max_len);
+bool     audiod_control_xfer_cb(uint8_t rhport, uint8_t stage, tusb_control_request_t const * request);
+bool     audiod_xfer_cb        (uint8_t rhport, uint8_t edpt_addr, xfer_result_t result, uint32_t xferred_bytes);
 
 #ifdef __cplusplus
 }
diff --git a/src/class/cdc/cdc_device.c b/src/class/cdc/cdc_device.c
index c24edb757..0a7691916 100644
--- a/src/class/cdc/cdc_device.c
+++ b/src/class/cdc/cdc_device.c
@@ -244,8 +244,8 @@ void cdcd_init(void)
     tu_fifo_config(&p_cdc->tx_ff, p_cdc->tx_ff_buf, TU_ARRAY_SIZE(p_cdc->tx_ff_buf), 1, true);
 
 #if CFG_FIFO_MUTEX
-    tu_fifo_config_mutex(&p_cdc->rx_ff, osal_mutex_create(&p_cdc->rx_ff_mutex));
-    tu_fifo_config_mutex(&p_cdc->tx_ff, osal_mutex_create(&p_cdc->tx_ff_mutex));
+    tu_fifo_config_mutex(&p_cdc->rx_ff, NULL, osal_mutex_create(&p_cdc->rx_ff_mutex));
+    tu_fifo_config_mutex(&p_cdc->tx_ff, osal_mutex_create(&p_cdc->tx_ff_mutex), NULL);
 #endif
   }
 }
diff --git a/src/class/midi/midi_device.c b/src/class/midi/midi_device.c
index 9ccbb733c..2c50bc4f3 100644
--- a/src/class/midi/midi_device.c
+++ b/src/class/midi/midi_device.c
@@ -378,8 +378,8 @@ void midid_init(void)
     tu_fifo_config(&midi->tx_ff, midi->tx_ff_buf, CFG_TUD_MIDI_TX_BUFSIZE, 1, false); // OBVS.
 
     #if CFG_FIFO_MUTEX
-    tu_fifo_config_mutex(&midi->rx_ff, osal_mutex_create(&midi->rx_ff_mutex));
-    tu_fifo_config_mutex(&midi->tx_ff, osal_mutex_create(&midi->tx_ff_mutex));
+    tu_fifo_config_mutex(&midi->rx_ff, NULL, osal_mutex_create(&midi->rx_ff_mutex));
+    tu_fifo_config_mutex(&midi->tx_ff, osal_mutex_create(&midi->tx_ff_mutex), NULL);
     #endif
   }
 }
diff --git a/src/class/vendor/vendor_device.c b/src/class/vendor/vendor_device.c
index 3fcea89c4..9b0a3c25f 100644
--- a/src/class/vendor/vendor_device.c
+++ b/src/class/vendor/vendor_device.c
@@ -146,8 +146,8 @@ void vendord_init(void)
     tu_fifo_config(&p_itf->tx_ff, p_itf->tx_ff_buf, CFG_TUD_VENDOR_TX_BUFSIZE, 1, false);
 
 #if CFG_FIFO_MUTEX
-    tu_fifo_config_mutex(&p_itf->rx_ff, osal_mutex_create(&p_itf->rx_ff_mutex));
-    tu_fifo_config_mutex(&p_itf->tx_ff, osal_mutex_create(&p_itf->tx_ff_mutex));
+    tu_fifo_config_mutex(&p_itf->rx_ff, NULL, osal_mutex_create(&p_itf->rx_ff_mutex));
+    tu_fifo_config_mutex(&p_itf->tx_ff, osal_mutex_create(&p_itf->tx_ff_mutex), NULL);
 #endif
   }
 }