Joren/qbz
1
0 Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

fix: disable PipeWire clock.force-quantum for rodio 0.22 compatibility

Browse Source 
rodio 0.22's MixerDeviceSink has an internal mixer thread that cannot
synchronize with PipeWire's forced quantum scheduling. This caused
massive buffer underruns (600+) at sample rates >= 88.2kHz when Force
Bit Perfect was enabled.

clock.force-rate alone is sufficient for bit-perfect sample rate
switching. Logs confirm zero underruns at 88.2kHz and minimal underruns
at 192kHz (only during heavy I/O) when quantum is not forced.
This commit is contained in:
vicrodh committed 2026-02-28 07:48:03 -06:00
1 parent 3d8733181a
commit 014becfb02
1 file changed
+6 -32
Download Patch File Download Diff File Expand all files Collapse all files
crates/qbz-audio/src/pipewire_backend.rs
+6 -32
View File
@@ -21,17 +21,6 @@ pub struct PipeWireBackend {
host: rodio::cpal::Host,
}
/// Calculate the optimal PipeWire quantum for a given sample rate.
/// Returns a power-of-2 value matching common audio interface expectations.
fn quantum_for_sample_rate(sample_rate: u32) -> u32 {
match sample_rate {
r if r <= 48000 => 1024,
r if r <= 96000 => 2048,
r if r <= 192000 => 4096,
_ => 8192,
}
}
impl PipeWireBackend {
pub fn new() -> BackendResult<Self> {
Ok(Self {
@@ -41,6 +30,7 @@ impl PipeWireBackend {
/// Reset PipeWire clock.force-rate and clock.force-quantum to 0.
/// Call this when playback stops so other apps aren't stuck at a forced rate.
/// Quantum reset is kept for safety even though we no longer force it.
pub fn reset_pipewire_clock() {
log::info!("[PipeWire Backend] Resetting clock.force-rate and clock.force-quantum to 0");
let _ = Command::new("pw-metadata")
@@ -217,27 +207,11 @@ impl AudioBackend for PipeWireBackend {
}
}
// Force quantum if bit-perfect mode is enabled
if config.pw_force_bitperfect {
let quantum = quantum_for_sample_rate(config.sample_rate);
log::info!("[PipeWire Backend] Forcing quantum to {} via pw-metadata (bit-perfect)", quantum);
let quantum_result = Command::new("pw-metadata")
.args(["-n", "settings", "0", "clock.force-quantum", &quantum.to_string()])
.output();
match quantum_result {
Ok(output) if output.status.success() => {
log::info!("[PipeWire Backend] Quantum forced to {}", quantum);
}
Ok(output) => {
let stderr = String::from_utf8_lossy(&output.stderr);
log::warn!("[PipeWire Backend] Failed to force quantum: {}", stderr);
}
Err(e) => {
log::warn!("[PipeWire Backend] Error executing pw-metadata for quantum: {}", e);
}
}
}
// Note: clock.force-quantum is intentionally NOT set.
// rodio 0.22's MixerDeviceSink has its own internal mixer thread that
// cannot synchronize with PipeWire's forced quantum, causing massive
// buffer underruns at sample rates >= 88.2kHz. clock.force-rate alone
// is sufficient for bit-perfect sample rate switching.
// Wait for PipeWire to apply the sample rate change
std::thread::sleep(std::time::Duration::from_millis(300));