start_loopback_capture hardcoded channels=1, forcing miniaudio to downmix the system's stereo mix to mono before the encoder saw it -- on_capture_frame then upmixed L=R to produce fake stereo. Now the loopback device opens in the channel's mode (stereo when the channel is stereo), CaptureCallback carries an explicit channels param so the encoder gets real interleaved L/R, and a mono fallback covers unusual render endpoints. New test_loopback_stereo_capture asserts L!=R end-to-end; 18/18 ctest green.
RemoteStream::playout_ts was seeded to 0 and only advanced inside the
decode loop (including on every PLC iteration), so it free-ran at ~1x
wall-clock regardless of whether the sender was transmitting. The
sender's frame timestamps only advance while it actually sends (the
VAD/PTT gate returns before ls.timestamp += samples). Across a late join
or any VAD/PTT silence gap the two clocks diverged without bound; once
past the jitter buffer's 500 ms late-drop window every real frame was
dropped-as-late (clock ahead) or never-due (clock behind) -> permanent
silence, while the talk indicator (driven by push_recv_frame, independent
of the jitter buffer) stayed lit.
Add JitterBuffer::peek_front_ts() (try-lock, RT-safe) and seed/re-sync
playout_ts to the earliest buffered frame on the first frame and whenever
it has drifted past +/-200/500 ms. This seeds startup and recovers after
every silence gap.
New regression test test_playout_resync free-runs the clock ~2 s past the
drop window, pushes a ts=0 frame, and asserts audible output: fails
(energy=0) without the fix, passes with it. ctest --preset m1-dev: 14/14.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
AudioEngine::on_capture() was passing miniaudio's hardware callback period
(commonly 480 samples / 10 ms on WASAPI shared mode) directly to opus_encode(),
which requires exactly frame_samples_ (960 for 20 ms @ 48 kHz). The mismatch
returned OPUS_BAD_ARG and silently dropped every real mic frame, while screen
share and injected test frames happened to be correctly sized and worked fine.
Fix: accumulate PCM in a pre-allocated CaptureAccum buffer (mirroring the
existing RemoteStream::ring fix on the playback side) and only call capture_cb_
when a full frame_samples_ chunk is ready. Same pattern applied to on_loopback().
Add test_capture_frame_accumulation() to verify the accumulator fires exactly the
right number of callbacks for misaligned chunk sizes (480, 240+720, 1920 samples).
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Closes the three items PROGRESS.md's M3 section explicitly carried forward as
out of scope:
- Device enumeration (vc_list_devices) + input device selection
(vc_set_input_device), backed by AudioEngine::enumerate_devices() via
miniaudio's ma_context_get_devices. Device ids are opaque hex-encoded
ma_device_id strings.
- VAD/PTT send-side input gate (vc_set_input_mode, vc_set_push_to_talk).
webrtc-audio-processing (the originally-planned APM) has no working
Windows/MSVC build upstream (GCC-only Meson, unfinished MinGW support, hard
abseil-cpp dependency), so VAD is a new lightweight, dependency-free
energy/RMS processor (EnergyVadProcessor) behind the existing ApmProcessor
interface. Gating is MIC-only; SCREEN_AUDIO/AUX_DEVICE always bypass it.
- True stereo playback: AudioEngine's mixer and output device now carry
stereo end-to-end (mono streams upmix L=R) instead of downmixing decoded
stereo streams to mono before mixing.
- Real WASAPI loopback capture for SCREEN_AUDIO (Windows-only, via
miniaudio's loopback device type), replacing test-only injection as the
production capture path.
Also: vccli gains --list-devices, --input-device, --input-mode, and
--share-screen-audio flags, plus a stdin command loop (ptt on/off, mode
vad/ptt) for manual verification. New test_vad_ptt_devices.cpp covers all
four items (ABI-level + a white-box AudioEngine stereo-mix check).
Docs updated to match: voice.md, roadmap.md (decision-log entry superseding
the original webrtc-audio-processing choice), tech-stack.md, README.md,
architecture.md, CLAUDE.md, PROGRESS.md.
Still explicitly out of scope, documented not silently dropped: real
webrtc-audio-processing/AEC (no AEC/NS/AGC exists at all yet), macOS/iOS
SCREEN_AUDIO capture, process-specific loopback, and a pre-existing
RT-thread rule violation in the capture path that predates this work.
Verified: ctest 12/12 green across 3 consecutive full-suite runs (both dev
and m1-dev presets build clean); test_vad_ptt_devices passed 5 consecutive
standalone runs; manually verified live (vccli --list-devices against real
hardware, vccli --voice --input-mode vad streaming without incident).
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
