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-rw-r--r--src/class/audio/audio_device.h18
1 files changed, 14 insertions, 4 deletions
diff --git a/src/class/audio/audio_device.h b/src/class/audio/audio_device.h
index 5a469523c..f406cf281 100644
--- a/src/class/audio/audio_device.h
+++ b/src/class/audio/audio_device.h
@@ -186,6 +186,11 @@
#define CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP 0 // Feedback - 0 or 1
#endif
+// Enable/disable conversion from 16.16 to 10.14 format on full-speed devices. See tud_audio_n_fb_set().
+#ifndef CFG_TUD_AUDIO_ENABLE_FEEDBACK_FORMAT_CORRECTION
+#define CFG_TUD_AUDIO_ENABLE_FEEDBACK_FORMAT_CORRECTION 0 // 0 or 1
+#endif
+
// 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)
@@ -454,10 +459,15 @@ TU_ATTR_WEAK bool tud_audio_rx_done_post_read_cb(uint8_t rhport, uint16_t n_byte
#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.
+
+// This function is used to provide data rate feedback from an asynchronous sink. Feedback value will be sent at FB endpoint interval till it's changed.
+//
+// The feedback format is specified to be 16.16 for HS and 10.14 for FS devices (see Universal Serial Bus Specification Revision 2.0 5.12.4.2). By default,
+// the choice of format is left to the caller and feedback argument is sent as-is. If CFG_TUD_AUDIO_ENABLE_FEEDBACK_FORMAT_CORRECTION is set, then tinyusb
+// expects 16.16 format and handles the conversion to 10.14 on FS.
+//
+// Note that due to a bug in its USB Audio 2.0 driver, Windows currently requires 16.16 format for _all_ USB 2.0 devices. On Linux and macOS it seems the
+// driver can work with either format. So a good compromise is to keep format correction disabled and stick to 16.16 format.
bool tud_audio_n_fb_set(uint8_t func_id, uint32_t feedback);
static inline bool tud_audio_fb_set(uint32_t feedback);
#endif