fix(alsa): buffering behavior on PipeWire-ALSA #1033
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Avoid setting period count when BufferSize::Default is used, allowing PipeWire-ALSA to select optimal buffer and period sizes. This prevents excessively large periods and high latency on PipeWire-ALSA devices.
roderickvd
changed the title
roderickvd
changed the title
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Note to self: drop should wait for two periods worth of time, not the full buffer. |
Set buffer_size_near before period_size_near for Fixed buffer sizes to constrain total latency and avoid extremely large allocations (eg. PipeWire-ALSA creating ~1M-frame buffers). Then set period_size to keep double-buffering semantics. Adjust avail_min by direction: for playback wake when level drops to one period (buffer - period); for capture wake when one period is available (period) to prevent excessive capture latency.
Revert to v0.16 behavior: always terminate stream without attempting state-based drain or wait. Remove buffer-duration calculation and snd_pcm_wait usage to avoid delays during drop.
Query the device's period size and set buffer_size to 2 * period for BufferSize::Default. This prevents excessive memory allocation (e.g. PipeWire-ALSA) while respecting the device's period preference.
This should always align with the two-period double-buffering strategy that we use anyway.
jwagner
approved these changes
Nov 2, 2025
| // buffer_size = 2x and period_size = x. This provides consistent low-latency | ||
| // behavior across different ALSA implementations and hardware. | ||
| if let BufferSize::Fixed(buffer_frames) = config.buffer_size { | ||
| hw_params.set_buffer_size_near((2 * buffer_frames) as _)?; |
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Might be better to use into here so there is a compile time error in case the types become incompatible.
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Fixes high latency with
BufferSize::Defaulton PipeWire-ALSA by avoiding period count constraints that cause pathologically large periods.Fixes