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fix: clamp audio input channels to stereo to prevent WebRTC crash #67

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fix: clamp audio input channels to stereo to prevent WebRTC crash #67

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4 changes: 3 additions & 1 deletion Runtime/Scripts/RtcSources/Audio/MicrophoneRtcAudioSource.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -70,7 +70,9 @@ private MicrophoneRtcAudioSource(
using var request = FFIBridge.Instance.NewRequest<NewAudioSourceRequest>();
var newAudioSource = request.request;
newAudioSource.Type = AudioSourceType.AudioSourceNative;
newAudioSource.NumChannels = deviceMicrophoneAudioSource.MicrophoneInfo.channels;
// Clamp to stereo — voice chat only needs mono/stereo, and the
// underlying WebRTC AudioFrame crashes with >8 channels.
newAudioSource.NumChannels = Math.Min(deviceMicrophoneAudioSource.MicrophoneInfo.channels, 2);
newAudioSource.SampleRate = SampleRate.Hz48000.valueHz;

using var options = request.TempResource<AudioSourceOptions>();
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8 changes: 7 additions & 1 deletion RustAudio/rust-audio/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -333,7 +333,13 @@ fn rust_audio_input_stream_new_internal(device_name: &str) -> Result<(StreamId,
.find(|c| c.sample_format() == cpal::SampleFormat::F32)
.ok_or(anyhow!("device doesn't support f32 samples"))?;

let config = config_range.with_max_sample_rate().config();
let mut config = config_range.with_max_sample_rate().config();

// Clamp to stereo — voice chat only needs mono/stereo, and WebRTC's
// AudioFrame asserts num_channels <= kMaxConcurrentChannels (8).
// Multi-channel audio interfaces (e.g. Scarlett 18i20 with 20 channels)
// would otherwise cause a fatal crash.
config.channels = config.channels.min(2);

let next_id = NEXT_STREAM_ID.fetch_add(1, std::sync::atomic::Ordering::Relaxed);
let moved_id = next_id;
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