Files
punktfunk/crates/pf-client-core/src/audio_wasapi.rs
T
enricobuehler 12a5318397 fix(audio): place audio with the picture instead of wherever the ring settles
The host stamps `pts_ns` on every audio datagram and the client decoded it
into `AudioPacket` — and then never read it. Video's `pts_ns` is used end to
end (the presenter computes a true glass-to-glass `displayed + clock_offset −
pts`), so audio free-ran at whatever depth its jitter ring happened to reach,
video was presented on an independent path, and nothing ever compared them.
The A/V offset was an accident of buffer depths: it moved whenever the ring
ratcheted under underrun pressure, and it got WORSE every time video got
faster, because a quicker decoder lowers the video leg and leaves audio's
exactly where it was. That is what a field report on the Steam Deck heard as
"the audio delay is way too high", and it is why shaving milliseconds off the
audio budget had not helped.

Video is the master. In a game streamer the video leg is the input-feel budget
and must never be inflated to satisfy the audio clock, while audio tolerates
small crossfaded corrections that are inaudible — and `crossfade_drop` already
applies them. So audio moves:

  audio_e2e = (now + buffered_ahead + clock_offset) − pts_ns
  av_offset = audio_e2e − video_e2e        (> 0 ⇒ audio behind the picture)

`AvSync` smooths that with an EWMA, ignores what sits inside a deadband no
listener can detect, refuses the implausible outright rather than clamping it
(a wall-clock step must not steer the ring), and proposes a depth.

Continuity outranks sync, always. `JitterPolicy::set_sync_target` only ever
takes a REQUEST, clamped between the existing underrun-driven floor and the
hard cap. A link whose jitter genuinely needs more buffer than the picture is
away keeps its buffer and the residual is reported — sync can never starve the
ring into dropouts. `None` is the default and reproduces the previous behaviour
exactly, so the four client rings can adopt this one at a time without
diverging.

Two upstream defects found on the way, both prerequisites:

* The host stamped `pts_ns` at ENCODE time, inside the loop draining an
  already-accumulated chunk, so every frame of a chunk carried near-identical
  timestamps describing when we got round to encoding. Harmless while nothing
  consumed it; a sync loop regulating against it would regulate against a
  fiction. It now comes off the capture clock.
* The host did not pace. One capture callback hands over a whole quantum — 5 ms
  when the graph honours our ask, 21.3 ms on a VM, where stock PipeWire raises
  `min-quantum` to 1024 — and the loop drained all of it into back-to-back
  `send_datagram` calls. The wire carried a 4-5 frame burst then ~21 ms of
  nothing, and a ring can only absorb that by standing a burst period deep.
  Frames now leave on the audio clock, which costs no average latency.

And the reason none of this was visible: `buffer_ms`/`target_ms` existed only
as a `tracing::debug!` line, absent from `Stats`. On a Deck the client runs
under Steam's `reaper` with stdout on a pipe nobody can read, so the one number
identifying a deep ring was unobtainable on the device reporting the latency.
The HUD now carries `audio buffer N ms · a/v ±N ms` — both, because a deep ring
on a jittery link is correct and only the offset separates that from audio held
late. The host also reports its negotiated quantum against the one it asked
for, per capture open rather than once per process.

Verified: 364 core + 40 presenter tests on Linux, clippy -D warnings clean on
punktfunk-{core,host} + pf-{client-core,presenter}, fmt clean. New tests pin
the safety invariant (sync cannot pull the target below the continuity floor on
any preset), that `None` leaves the policy bit-identical, and that a device
quantum exceeding the hard cap does not panic `Ord::clamp` inside a realtime
callback.

Android and Apple keep today's behaviour (the `None` default) until their
presenters publish a video figure to align against; design/audio-latency-
overhaul.md carries the plan.
2026-08-07 23:33:45 +02:00

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//! Audio: playback (decoded PCM → a WASAPI shared-mode render stream) and the microphone
//! uplink (WASAPI capture → Opus → 0xCB datagrams, the inverse of the host's virtual mic).
//!
//! The WASAPI twin of `audio.rs` (PipeWire) — same public surface (`AudioPlayer::spawn`/
//! `take_buffer`/`push`, `MicStreamer::spawn`), swapped in by lib.rs's `#[path]` so the
//! session pump compiles against one `crate::audio` on both OSes. It began as a copy of the
//! WinUI shell's own audio path; that shell's built-in streaming path has since been deleted,
//! so this is now the only WASAPI client ring.
//!
//! Playback: the session pump pushes 5 ms Opus-decoded chunks on the network clock; the WASAPI
//! render thread pulls whole event-driven quanta on the device clock. The depth policy between
//! them is the SHARED `punktfunk_core::audio::JitterPolicy` (`JitterTuning::WASAPI`) — target in
//! milliseconds, crossfaded drift correction, de-prime hysteresis — so all four clients behave
//! the same way and none of them can ratchet latency upward.
//!
//! WASAPI objects are COM-apartment-bound and not `Send`, so they live on a dedicated
//! thread (the same discipline as the host's `wasapi_cap`); only the channels + stop flag
//! + join handle cross the boundary.
use anyhow::{anyhow, Context, Result};
use punktfunk_core::client::NativeClient;
use std::collections::VecDeque;
use std::sync::atomic::{AtomicBool, Ordering};
use std::sync::mpsc::{Receiver, SyncSender, TrySendError};
use std::sync::Arc;
use std::time::Duration;
use wasapi::{
AudioClientProperties, DeviceEnumerator, Direction, SampleType, StreamCategory, StreamMode,
WaveFormat,
};
const SAMPLE_RATE: usize = 48_000;
/// Mic capture requests STEREO from WASAPI (autoconvert matrixes any endpoint layout down to
/// it — the proven path; `read_from_device_to_deque` then delivers our requested format) and
/// downmixes to MONO in code before the encoder: voice is mono at the source, the host accepts
/// any Opus channel layout (its stereo decoder upmixes), and half the samples halve the
/// encode + wire cost. The render path is multichannel — its channel count + block align are
/// runtime, driven by the host-resolved layout.
const CAPT_CHANNELS: usize = 2;
/// Mic frames are 10 ms (480 mono samples) — any size ≤ 120 ms is fine host-side; 10 ms
/// halves the frame-fill share of mouth-to-ear latency vs the old 20 ms.
const MIC_FRAME: usize = 480;
/// A selectable WASAPI endpoint for the settings pickers.
#[derive(Clone, Debug)]
pub struct AudioDevice {
/// The `IMMDevice` endpoint id (`{0.0.0.00000000}.{…}`) — the stable key the render and
/// capture threads resolve via [`DeviceEnumerator::get_device`]. (The PipeWire twin
/// stores `node.name` here; both are "the stable key", so the Settings fields and env
/// contract stay OS-agnostic.)
pub name: String,
/// The endpoint's friendly name ("Speakers (Realtek …)") — what the picker shows.
pub description: String,
}
/// Enumerate active audio endpoints: `(sinks, sources)` — the WASAPI twin of the PipeWire
/// probe (same tuple shape; no devices → the caller simply shows no pickers). Runs on its
/// own short-lived MTA thread: the caller is typically a UI thread whose COM apartment is
/// STA, where a direct `CoInitializeEx(MTA)` would fail with `RPC_E_CHANGED_MODE`.
pub fn devices() -> Result<(Vec<AudioDevice>, Vec<AudioDevice>)> {
std::thread::Builder::new()
.name("pf-audio-enum".into())
.spawn(|| -> Result<(Vec<AudioDevice>, Vec<AudioDevice>)> {
wasapi::initialize_mta()
.ok()
.context("CoInitializeEx (MTA)")?;
let enumerator = DeviceEnumerator::new().context("DeviceEnumerator")?;
let mut out = (Vec::new(), Vec::new());
for (direction, list) in [
(Direction::Render, &mut out.0),
(Direction::Capture, &mut out.1),
] {
let coll = enumerator
.get_device_collection(&direction)
.context("device collection")?;
for i in 0..coll.get_nbr_devices().context("device count")? {
// One broken endpoint (driver limbo) must not hide the rest.
let Ok(dev) = coll.get_device_at_index(i) else {
continue;
};
let (Ok(id), Ok(name)) = (dev.get_id(), dev.get_friendlyname()) else {
continue;
};
list.push(AudioDevice {
name: id,
description: name,
});
}
}
Ok(out)
})
.context("spawn audio enumeration thread")?
.join()
.map_err(|_| anyhow!("audio enumeration thread panicked"))?
}
/// The endpoint an env pick names (`PUNKTFUNK_AUDIO_SINK`/`SOURCE` — endpoint ids, the
/// Settings device pickers via session main), or the OS default. A picked device that's
/// gone (unplugged USB DAC, remote session) falls back to the default with a warning —
/// audio keeps working, like the PipeWire twin's `target.object` behavior.
/// Resolve an active endpoint by id WITHOUT `DeviceEnumerator::get_device`.
///
/// That helper builds its argument as `PCWSTR::from_raw(HSTRING::from(id).as_ptr())` — the
/// `HSTRING` is a temporary, dropped at the end of that statement, so `GetDevice` reads freed
/// memory and misses ids that are perfectly valid. Scanning the active collection touches only
/// safe crate APIs, so it cannot regress the same way. (`punktfunk-host` fixes the same bug with
/// raw COM instead; this crate cannot, because it pins a different `windows` revision than
/// `wasapi` does, making the two `IMMDevice` types incompatible.)
pub(crate) fn device_by_id(
enumerator: &DeviceEnumerator,
direction: &Direction,
id: &str,
) -> Result<wasapi::Device> {
let devices = enumerator
.get_device_collection(direction)
.map_err(|e| anyhow!("enumerate {direction:?} endpoints: {e}"))?;
let count = devices
.get_nbr_devices()
.map_err(|e| anyhow!("endpoint count: {e}"))?;
for i in 0..count {
let dev = devices
.get_device_at_index(i)
.map_err(|e| anyhow!("endpoint {i}: {e}"))?;
if dev.get_id().is_ok_and(|got| got == id) {
return Ok(dev);
}
}
anyhow::bail!("no active {direction:?} endpoint with id {id}")
}
fn pick_device(
enumerator: &DeviceEnumerator,
direction: &Direction,
var: &str,
) -> Result<wasapi::Device> {
if let Some(id) = std::env::var(var).ok().filter(|v| !v.is_empty()) {
match device_by_id(enumerator, direction, &id) {
Ok(d) => {
tracing::info!(
var,
endpoint = %d.get_friendlyname().unwrap_or_else(|_| id.clone()),
"using the picked audio endpoint"
);
return Ok(d);
}
Err(e) => tracing::warn!(
var,
endpoint_id = %id,
error = %e,
"picked audio endpoint not found — using the default"
),
}
}
enumerator
.get_default_device(direction)
.context("default endpoint")
}
pub struct AudioPlayer {
pcm_tx: SyncSender<Vec<f32>>,
/// Drained chunk Vecs coming back from the render thread for reuse (the pool half of
/// the pcm channel — see [`AudioPlayer::take_buffer`]).
recycle_rx: Receiver<Vec<f32>>,
stop: Arc<AtomicBool>,
thread: Option<std::thread::JoinHandle<()>>,
/// A/V sync hand-off with the render thread: it publishes the ring depth, the decode thread
/// posts the depth the sync loop wants. See [`punktfunk_core::audio::AudioSyncCell`].
sync: Arc<punktfunk_core::audio::AudioSyncCell>,
}
impl AudioPlayer {
/// Spawn the WASAPI render thread for `channels` (2/6/8, canonical wire order
/// FL FR FC LFE RL RR SL SR). Failure (no render endpoint on this box) is survivable — the
/// caller streams video-only.
pub fn spawn(channels: u32) -> Result<AudioPlayer> {
// 64 × 5 ms = 320 ms of slack between the pump and the WASAPI loop.
let (pcm_tx, pcm_rx) = std::sync::mpsc::sync_channel::<Vec<f32>>(64);
// Return path: the render thread sends each drained Vec back for reuse, so
// steady-state playback stops allocating (~200 chunks/s otherwise). Same capacity
// as the data channel; a full pool just drops the Vec (plain deallocation).
let (recycle_tx, recycle_rx) = std::sync::mpsc::sync_channel::<Vec<f32>>(64);
let stop = Arc::new(AtomicBool::new(false));
let (ready_tx, ready_rx) = std::sync::mpsc::sync_channel::<Result<()>>(1);
let stop_t = stop.clone();
let sync: Arc<punktfunk_core::audio::AudioSyncCell> = Arc::default();
let sync_t = sync.clone();
let thread = std::thread::Builder::new()
.name("punktfunk-audio".into())
.spawn(move || {
if let Err(e) =
render_thread(pcm_rx, recycle_tx, stop_t, ready_tx, channels as u8, sync_t)
{
tracing::warn!(error = %format!("{e:#}"), "audio playback thread ended");
}
})
.context("spawn audio thread")?;
match ready_rx.recv_timeout(Duration::from_secs(3)) {
Ok(Ok(())) => {
// Default endpoint unless PUNKTFUNK_AUDIO_SINK picked one (logged there).
tracing::info!(channels, "WASAPI render: 48 kHz f32");
Ok(AudioPlayer {
pcm_tx,
recycle_rx,
stop,
thread: Some(thread),
sync,
})
}
Ok(Err(e)) => Err(e),
Err(_) => Err(anyhow!(
"wasapi render init timed out (no render endpoint?)"
)),
}
}
/// A recycled chunk Vec from the pool, empty but with its capacity intact — fill it
/// and hand it back through [`push`](Self::push). Allocates only when the pool is dry
/// (startup, or after the WASAPI side dropped chunks).
pub fn take_buffer(&self) -> Vec<f32> {
self.recycle_rx.try_recv().unwrap_or_default()
}
/// The A/V sync hand-off cell — the decode thread reads the ring depth from it and posts the
/// depth the sync loop wants back through it.
pub fn sync_cell(&self) -> Arc<punktfunk_core::audio::AudioSyncCell> {
self.sync.clone()
}
/// Queue one interleaved f32 chunk (in the session's channel layout). Drops the chunk if the
/// WASAPI side is wedged (the renderer conceals the gap; never block the session pump).
pub fn push(&self, pcm: Vec<f32>) {
if let Err(TrySendError::Disconnected(_)) = self.pcm_tx.try_send(pcm) {
// Thread already dead — Drop will reap it; nothing to do per-chunk.
}
}
}
impl Drop for AudioPlayer {
fn drop(&mut self) {
self.stop.store(true, Ordering::SeqCst);
if let Some(t) = self.thread.take() {
let _ = t.join();
}
}
}
fn render_thread(
pcm_rx: Receiver<Vec<f32>>,
recycle_tx: SyncSender<Vec<f32>>,
stop: Arc<AtomicBool>,
ready: SyncSender<Result<()>>,
channels: u8,
sync: Arc<punktfunk_core::audio::AudioSyncCell>,
) -> Result<()> {
if let Err(e) = wasapi::initialize_mta()
.ok()
.context("CoInitializeEx (MTA)")
{
let _ = ready.send(Err(e));
return Ok(());
}
let res = (|| -> Result<()> {
// F32LE interleaved: channels × 4 bytes/sample. Stereo (channels == 2) is byte-identical
// to the old fixed path (mask 0x3, block align 8).
let block_align = channels as usize * 4;
let enumerator = DeviceEnumerator::new().context("DeviceEnumerator")?;
let device = pick_device(&enumerator, &Direction::Render, "PUNKTFUNK_AUDIO_SINK")
.context("render endpoint")?;
let mut audio_client = device.get_iaudioclient().context("IAudioClient")?;
// The explicit dwChannelMask is the wire order (FL FR FC LFE RL RR SL SR); 5.1 = 0x3F,
// 7.1 = 0x63F. WASAPI delivers channels in ascending mask-bit order, which equals the wire
// order, so the render mapping is the identity — no permute. `autoconvert` (below) lets the
// audio engine downmix when the endpoint has fewer speakers.
let desired = WaveFormat::new(
32,
32,
&SampleType::Float,
SAMPLE_RATE,
channels as usize,
Some(punktfunk_core::audio::wasapi_channel_mask(channels)),
);
let (default_period, _min_period) =
audio_client.get_device_period().context("device period")?;
let mode = StreamMode::EventsShared {
autoconvert: true,
buffer_duration_hns: default_period,
};
audio_client
.initialize_client(&desired, &Direction::Render, &mode)
.context("initialize render client")?;
let h_event = audio_client.set_get_eventhandle().context("event handle")?;
let render_client = audio_client
.get_audiorenderclient()
.context("IAudioRenderClient")?;
audio_client.start_stream().context("start render stream")?;
let _ = ready.send(Ok(()));
// De-jitter ring, in interleaved f32 SAMPLES (it used to be raw bytes, which made the
// depth arithmetic byte-vs-sample and kept it from sharing the policy and the crossfade
// helper with the other three clients).
let mut ring: VecDeque<f32> = VecDeque::new();
// Shared ms-denominated policy: prime depth, crossfaded drift correction so latency
// returns to target instead of ratcheting, and de-prime hysteresis — the last replacing
// the old `if ring.is_empty()`, where a single transient drain manufactured a whole
// target's worth of fresh silence.
let mut policy = punktfunk_core::audio::JitterPolicy::new(
punktfunk_core::audio::JitterTuning::WASAPI,
channels,
);
let mut out = Vec::new(); // per-quantum scratch, reused across iterations
let (mut underruns, mut sheds, mut callbacks) = (0u64, 0u64, 0u64);
while !stop.load(Ordering::Relaxed) {
if h_event.wait_for_event(100).is_err() {
continue;
}
// Drain everything the pump has queued into the ring, returning each drained
// Vec to the pool (a full/closed pool drops it).
while let Ok(mut chunk) = pcm_rx.try_recv() {
ring.extend(chunk.iter().copied());
chunk.clear();
let _ = recycle_tx.try_send(chunk);
}
let avail_frames = audio_client
.get_available_space_in_frames()
.context("available space")? as usize;
if avail_frames == 0 {
continue;
}
let want = avail_frames * channels as usize;
// A/V sync: same contract as the PipeWire ring — take the decode thread's request,
// publish where the ring actually is. The policy clamps the request against its own
// underrun floor, so continuity always outranks alignment.
policy.set_sync_target(sync.target());
sync.publish_depth(ring.len());
let step = policy.step(ring.len(), want);
if step.drop_front > 0 {
sheds += 1;
punktfunk_core::audio::crossfade_drop(&mut ring, step.drop_front, step.crossfade);
}
out.clear();
out.resize(avail_frames * block_align, 0);
let mut ran_short = false;
if !step.silence {
// `out` is exactly `want` f32s wide (avail_frames × channels × 4 bytes).
for dst in out.chunks_exact_mut(4) {
let s = ring.pop_front().unwrap_or_else(|| {
ran_short = true;
0.0
});
dst.copy_from_slice(&s.to_le_bytes());
}
}
// No-op while un-primed (the policy ignores it), so a deliberate priming silence is
// never miscounted as an underrun.
policy.note_read(ran_short);
underruns += u64::from(ran_short);
callbacks += 1;
if callbacks % 1_000 == 0 {
tracing::debug!(
buffer_ms = policy.avg_depth_ms(),
target_ms = policy.target_ms(),
underruns,
drift_sheds = sheds,
"audio playback"
);
}
render_client
.write_to_device(avail_frames, &out, None)
.context("write_to_device")?;
}
audio_client.stop_stream().ok();
Ok(())
})();
if let Err(ref e) = res {
let _ = ready.send(Err(anyhow!("{e:#}")));
}
res
}
/// The microphone uplink: capture the default input device, Opus-encode 10 ms mono chunks,
/// ship them as 0xCB datagrams into the host's virtual mic source.
pub struct MicStreamer {
stop: Arc<AtomicBool>,
thread: Option<std::thread::JoinHandle<()>>,
}
impl MicStreamer {
/// `muted` is the in-stream mute (B4), shared live with the capture loop: set, the loop
/// keeps reading the endpoint and discarding whole frames but sends nothing. Muting by
/// STOPPING the client was rejected — an `IAudioClient` stop/start re-primes the endpoint
/// buffers and re-runs the category negotiation below on every unmute.
///
/// `echo_cancel` is the Settings toggle; `PUNKTFUNK_NO_AEC=1` overrides it off.
pub fn spawn(
connector: Arc<NativeClient>,
muted: Arc<AtomicBool>,
echo_cancel: bool,
) -> Result<MicStreamer> {
let stop = Arc::new(AtomicBool::new(false));
let stop_t = stop.clone();
let thread = std::thread::Builder::new()
.name("punktfunk-mic".into())
.spawn(move || {
if let Err(e) = mic_thread(&connector, stop_t, muted, echo_cancel) {
tracing::warn!(error = %format!("{e:#}"), "mic uplink thread ended");
}
})
.context("spawn mic thread")?;
Ok(MicStreamer {
stop,
thread: Some(thread),
})
}
}
impl Drop for MicStreamer {
fn drop(&mut self) {
self.stop.store(true, Ordering::SeqCst);
if let Some(t) = self.thread.take() {
let _ = t.join();
}
}
}
/// Whether the mic echo-cancellation hooks run this session: the `echo_cancel` setting, with
/// `PUNKTFUNK_NO_AEC=1` as a one-way override OFF. The env var wins — it is the escape hatch
/// for a box whose canceller misbehaves, and it predates the setting; nothing turns AEC back
/// on once it is set. Here the hook is the Communications stream category below; the PipeWire
/// twin gates its echo-cancelled-source preference the same way.
fn aec_enabled(echo_cancel: bool) -> bool {
echo_cancel && !std::env::var("PUNKTFUNK_NO_AEC").is_ok_and(|v| !v.is_empty() && v != "0")
}
fn mic_thread(
connector: &Arc<NativeClient>,
stop: Arc<AtomicBool>,
muted: Arc<AtomicBool>,
echo_cancel: bool,
) -> Result<()> {
wasapi::initialize_mta()
.ok()
.context("CoInitializeEx (MTA)")?;
let mut encoder = opus::Encoder::new(
SAMPLE_RATE as u32,
opus::Channels::Mono,
opus::Application::Voip,
)
.map_err(|e| anyhow!("opus encoder: {e}"))?;
// Voice tuning: 48 kbps mono is transparent for speech; in-band FEC + an assumed 10 %
// loss let the host's decoder rebuild a lost 0xCB datagram from its successor instead
// of concealing (datagrams are fire-and-forget — this FEC is the only redundancy).
let _ = encoder.set_bitrate(opus::Bitrate::Bits(48_000));
let _ = encoder.set_inband_fec(true);
let _ = encoder.set_packet_loss_perc(10);
let enumerator = DeviceEnumerator::new().context("DeviceEnumerator")?;
let device = pick_device(&enumerator, &Direction::Capture, "PUNKTFUNK_AUDIO_SOURCE")
.context("capture endpoint (no microphone?)")?;
let mut audio_client = device.get_iaudioclient().context("IAudioClient")?;
// Communications category → the endpoint's communications signal-processing chain. A
// driver/APO stack with an echo canceller only engages it for communications-category
// streams; the default (Other) category never did, so the downlink audio playing on
// this box fed straight back into the host's virtual mic. Must precede Initialize
// (SetClientProperties is a pre-init call; the wasapi crate QIs IAudioClient2 inside).
// Best-effort: an endpoint without IAudioClient2 just keeps the default category.
// The "Echo cancellation" setting opts out, and PUNKTFUNK_NO_AEC=1 overrides that off
// (same lever as the Linux echo-cancel-source preference) — see `aec_enabled`.
if aec_enabled(echo_cancel) {
if let Err(e) = audio_client.set_properties(
AudioClientProperties::new().set_category(StreamCategory::Communications),
) {
tracing::debug!(error = %e, "mic capture: Communications category not set");
}
}
let desired = WaveFormat::new(32, 32, &SampleType::Float, SAMPLE_RATE, CAPT_CHANNELS, None);
let (default_period, _min_period) =
audio_client.get_device_period().context("device period")?;
let mode = StreamMode::EventsShared {
autoconvert: true,
buffer_duration_hns: default_period,
};
audio_client
.initialize_client(&desired, &Direction::Capture, &mode)
.context("initialize capture client")?;
let h_event = audio_client.set_get_eventhandle().context("event handle")?;
let capture_client = audio_client
.get_audiocaptureclient()
.context("IAudioCaptureClient")?;
audio_client
.start_stream()
.context("start capture stream")?;
let mut bytes: VecDeque<u8> = VecDeque::new();
let mut ring: VecDeque<f32> = VecDeque::new();
let mut out = vec![0u8; 4000];
let mut seq = 0u32;
while !stop.load(Ordering::Relaxed) {
if h_event.wait_for_event(100).is_err() {
continue;
}
loop {
match capture_client.get_next_packet_size() {
Ok(Some(0)) | Ok(None) => break,
Ok(Some(_n)) => {
capture_client
.read_from_device_to_deque(&mut bytes)
.context("read capture")?;
}
Err(e) => return Err(anyhow!("get_next_packet_size: {e}")),
}
}
// One stereo capture frame (8 bytes) → one mono sample: average L/R. Autoconvert
// already matrixed the endpoint's real layout (mono/stereo/array mic) into the
// stereo stream we initialized, so this is the only downmix left to do.
let stereo_frame = 4 * CAPT_CHANNELS;
let whole = (bytes.len() / stereo_frame) * stereo_frame;
for c in bytes
.drain(..whole)
.collect::<Vec<u8>>()
.chunks_exact(stereo_frame)
{
let l = f32::from_le_bytes([c[0], c[1], c[2], c[3]]);
let r = f32::from_le_bytes([c[4], c[5], c[6], c[7]]);
ring.push_back((l + r) * 0.5);
}
// Muted (B4): the capture client stays started and keeps its primed buffers — only
// the sending stops. Whole frames are discarded so the ring can't grow, and `seq`
// deliberately does NOT advance: the host sees one continuous sequence with a silent
// pause in the middle rather than a gap the size of the mute, which its de-jitter
// would try to conceal frame by frame.
if muted.load(Ordering::Relaxed) {
let drop_n = (ring.len() / MIC_FRAME) * MIC_FRAME;
ring.drain(..drop_n);
continue;
}
// Ship every complete 10 ms mono frame.
while ring.len() >= MIC_FRAME {
let pcm: Vec<f32> = ring.drain(..MIC_FRAME).collect();
match encoder.encode_float(&pcm, &mut out) {
Ok(len) => {
let pts = std::time::SystemTime::now()
.duration_since(std::time::UNIX_EPOCH)
.map(|d| d.as_nanos() as u64)
.unwrap_or(0);
let _ = connector.send_mic(seq, pts, out[..len].to_vec());
seq = seq.wrapping_add(1);
}
Err(e) => tracing::debug!(error = %e, "opus mic encode"),
}
}
}
audio_client.stop_stream().ok();
Ok(())
}