feat(audio): real noise suppression via vendored RNNoise (send + receive)
The two-sided NR plumbing (RemoteStream::recv_ns + the per-listener
vc_set_remote_stream noise_reduction toggle) was wired but inert:
ApmProcessor::create() returned a no-op passthrough, because the
originally-planned webrtc-audio-processing has no working Windows/macOS
build. Drop in RNNoise as the real backend behind the same ApmProcessor
interface, lighting up both NR paths.
- Vendor RNNoise (BSD-3 + CC0) at third_party/rnnoise/ — the vcpkg port
is !windows !arm, so it can't cover our primary targets. Shrunk int8
model (78MB -> 11.7MB via upstream scripts/shrink_model.sh), built as a
standalone C static lib with no RTCD (portable scalar path on x86,
auto-NEON on arm64) under -DDISABLE_DEBUG_FLOAT. Model is baked in
(rnnoise_create(NULL)); no runtime file.
- New RnnoiseProcessor (core/src/audio/apm_processor.cpp) selected by
ApmProcessor::create() when VOICECAT_HAS_NS. Mono/48kHz/480-sample;
our clock is fixed 48kHz and Opus frame sizes are multiples of 480, so
no resampling. RT-safe: allocates at construction, lock-free in the
capture/playback callbacks.
- Receive-side: lit up via the factory; gated to mono streams (a stereo
stream is a screen-audio share, not voice).
- Send-side (new): vc_set_input_noise_reduction(client, enable) ABI +
vc_client::mic_ns_, run before input gain/VAD in on_capture_frame. A
stereo mic is downmixed to mono ONLY when NR is on — with NR off a
stereo mic keeps full stereo (never collapse mic quality unasked).
- Enable C as a project language for the vendored lib.
- New noise_suppression test: white noise through ApmProcessor::create()
drops ~99.9% RMS. ctest --preset dev green, 28/28. windows-client DLL
builds clean with vc_set_input_noise_reduction exported, system-only deps.
- Docs synced: voice.md §10, tech-stack.md §1/§5, third_party/README.md,
vcpkg.json note, PROGRESS.md, CLAUDE.md.
Client on/off UI toggles (Windows/macOS/iOS) are the remaining follow-up.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
2026-06-23 13:30:54 +02:00
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Jean-Marc Valin <jmvalin@jmvalin.ca>
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