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https://github.com/mpv-player/mpv
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6863eefc3d
Currently, running AO control wakes up the WASAPI renderer thread in the `WASAPI_THREAD_FEED` state, where `thread_feed` will be called. However, it seems that in recent Windows versions (tested on Windows 10 build 19044.3930 and Windows 11 build 22631.3007) we can't know if it is safe to feed more audio data in event-driven exclusive mode: - `IAudioClient_GetCurrentPadding` always returns `bufferFrameCount`, even if *NO* data has ever been written. This means we don't know how much free space we have that is available for writing. This is not the case in shared mode, where the return value correctly reflects the size of data waiting to be processed. As a sidenote, MS did not document the precise definition of the return value for an event-driven, exclusive stream [1]. - `IAudioRenderClient_GetBuffer` never fails. We can call it for 10 times in a roll, each time requesting an entire buffer (the unit at which data is exchanged in exclusive mode using event-driven buffering; there are 2 such buffers) and get a successful return code everytime. In shared mode, we get `AUDCLNT_E_BUFFER_TOO_LARGE` if we request a buffer larger than that currently available. As a result, `thread_feed` will always write `bufferFrameCount` frames of audio in exclusive mode. There will therefore be glitches each time `thread_control` is called due to the subsequent `thread_feed` overwriting frames yet to be processed. Also, an irreversible error is accumulated to `sample_count` as long as there is no AO reset, leading to eventual, unbounded A/V desync. As a fix to the issue, add a dedicated state for dispatch queue processing so that `thread_feed` is only called when signaled by the OS. The buffer checks in `thread_feed` that use `GetCurrentPadding` in exclusive mode are kept in case there are older versions where the two APIs behave differently. Closes #12615. [1] https://learn.microsoft.com/en-us/windows/win32/api/audioclient/nf-audioclient-iaudioclient-getcurrentpadding |
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| .. | ||
| ao_alsa.c | ||
| ao_audiotrack.c | ||
| ao_audiounit.m | ||
| ao_coreaudio_chmap.c | ||
| ao_coreaudio_chmap.h | ||
| ao_coreaudio_exclusive.c | ||
| ao_coreaudio_properties.c | ||
| ao_coreaudio_properties.h | ||
| ao_coreaudio_utils.c | ||
| ao_coreaudio_utils.h | ||
| ao_coreaudio.c | ||
| ao_jack.c | ||
| ao_lavc.c | ||
| ao_null.c | ||
| ao_openal.c | ||
| ao_opensles.c | ||
| ao_oss.c | ||
| ao_pcm.c | ||
| ao_pipewire.c | ||
| ao_pulse.c | ||
| ao_sdl.c | ||
| ao_sndio.c | ||
| ao_wasapi_changenotify.c | ||
| ao_wasapi_utils.c | ||
| ao_wasapi.c | ||
| ao_wasapi.h | ||
| ao.c | ||
| ao.h | ||
| buffer.c | ||
| internal.h | ||