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>
Talon
7da0a02b3a