diff options
Diffstat (limited to 'src/class/audio/audio_host.h')
| -rw-r--r-- | src/class/audio/audio_host.h | 22 |
1 files changed, 15 insertions, 7 deletions
diff --git a/src/class/audio/audio_host.h b/src/class/audio/audio_host.h index 2e778c184..f83d7ea63 100644 --- a/src/class/audio/audio_host.h +++ b/src/class/audio/audio_host.h @@ -40,11 +40,14 @@ extern "C" { #ifndef CFG_TUH_AUDIO_MAX #define CFG_TUH_AUDIO_MAX 1 #endif -// Maximum number of discrete sampling frequencies per Audio Streaming interface +// Maximum discrete sampling frequencies retained per rate source. UAC1 uses +// one rate source per alternate setting; UAC2 alternate settings may share a +// Clock Source. #ifndef CFG_TUH_AUDIO_MAX_SAM_FREQ #define CFG_TUH_AUDIO_MAX_SAM_FREQ 5 #endif -// Maximum number of Audio Streaming interfaces per Audio device +// Maximum supported nonzero-bandwidth Audio Streaming alternate settings per +// logical stream. #ifndef CFG_TUH_AUDIO_MAX_AS #define CFG_TUH_AUDIO_MAX_AS 4 #endif @@ -169,20 +172,25 @@ bool tuh_audio_configure(uint8_t dev_idx, uint8_t stream_idx, uint8_t config_idx // Start transferring data with the configuration selected by configure(). // UAC1 activates the alternate setting before setting an endpoint frequency; // UAC2 sets a writable Clock Source before activating the alternate setting. +// Startup is asynchronous: true means that the first request was submitted. +// Later startup failures are reported through tuh_audio_err_cb(). bool tuh_audio_start(uint8_t dev_idx, uint8_t stream_idx); -// Stop transferring and deactivate the Audio Streaming interface (alt 0). +// Stop transferring and asynchronously deactivate the Audio Streaming +// interface (alt 0). true means that the deactivation request was submitted. bool tuh_audio_stop(uint8_t dev_idx, uint8_t stream_idx); // Frame-based transfer. One frame = channels * bytes per sample. // tuh_audio_write() is valid only for TUH_AUDIO_STREAM_PLAYBACK streams, // tuh_audio_read() only for TUH_AUDIO_STREAM_CAPTURE streams. +// Both functions are non-blocking and return immediately. // Returns the number of frames actually written/read (0 on any error, // including wrong direction, unconfigured/stopped stream, or full/empty FIFO). uint32_t tuh_audio_write(uint8_t dev_idx, uint8_t stream_idx, const void *buffer, uint32_t frame_count); uint32_t tuh_audio_read(uint8_t dev_idx, uint8_t stream_idx, void *buffer, uint32_t frame_count); -// FIFO occupancy in frames available for a non-blocking write/read. +// Number of frames that can be queued immediately for playback. uint32_t tuh_audio_write_available(uint8_t dev_idx, uint8_t stream_idx); +// Number of captured frames that can be read immediately. uint32_t tuh_audio_read_available(uint8_t dev_idx, uint8_t stream_idx); //--------------------------------------------------------------------+ @@ -297,9 +305,9 @@ void tuh_audio_umount_cb(uint8_t idx); // received data is already queued into the stream's capture FIFO. void tuh_audio_capture_cb(uint8_t idx, uint8_t stream_idx, uint16_t xferred_bytes); -// Invoked when an isochronous OUT transfer completes successfully: the -// next playback packet is submitted from the stream FIFO, or as silence when -// a complete packet is not queued. +// Invoked after a successful isochronous OUT transfer, before the next packet +// is prepared. After this callback returns, the driver submits queued audio +// from the stream FIFO, or silence when a complete packet is unavailable. void tuh_audio_playback_cb(uint8_t idx, uint8_t stream_idx, uint16_t xferred_bytes); // Invoked when asynchronous stream activation or an isochronous transfer |