fix: detect actual channel count to prevent Mickey Mouse with mono USB devices#67
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fix: detect actual channel count to prevent Mickey Mouse with mono USB devices#67
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…B devices Mono USB headsets (e.g. Jabra PRO 930) deliver 1-channel audio through the CATapDescription aggregate device. The code assumed stereo (2ch), treating consecutive mono samples as L/R pairs and averaging them — halving the sample count and producing double-speed Mickey Mouse audio. Fix: read mNumberChannels from AudioBufferList on first IOProc callback, propagate through AudioCaptureResult, and use for channel conversion.
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Tests verify: mono passthrough (no halving), stereo averaging, sample count preservation, empty input, and incomplete frames.
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Summary
AudioBufferList.mNumberChannelson first callbackactualChannelsthroughAudioCaptureResult→AudioCaptureSession→DualSourceRecorderappChannels=2for stereo→mono conversionRoot cause: Jabra PRO 930 USB headset has 1 output channel (mono). The aggregate device delivers mono audio, but the code always assumed stereo interleaved — averaging consecutive mono samples as L/R pairs, halving the sample count, producing double-speed Mickey Mouse voice.
Test Plan