wasm: fix stereo

src/audio/MiniAudioSource.cpp

@@ -43,13 +43,16 @@ std::vector<MiniAudioSource::DeviceInfo> MiniAudioSource::listInputDevices() {
             fullInfo = captureDevices[i];
         }
 
-        int maxCh = static_cast<int>(fullInfo.nativeDataFormatCount > 0
+        int maxCh = 0;
-                        ? fullInfo.nativeDataFormats[0].channels : 2);
+        if (fullInfo.nativeDataFormatCount > 0) {
-        // Find max channels across native formats.
+            for (ma_uint32 f = 0; f < fullInfo.nativeDataFormatCount; ++f) {
-        for (ma_uint32 f = 1; f < fullInfo.nativeDataFormatCount; ++f) {
+                int ch = static_cast<int>(fullInfo.nativeDataFormats[f].channels);
-            int ch = static_cast<int>(fullInfo.nativeDataFormats[f].channels);
+                if (ch > maxCh) maxCh = ch;
-            if (ch > maxCh) maxCh = ch;
+            }
         }
+        // channels == 0 means "any" in miniaudio (e.g. Web Audio backend).
+        // Default to 2 (stereo) so the UI can offer multi-channel mode.
+        if (maxCh <= 0) maxCh = 2;
 
         double defaultSR = 48000.0;
         if (fullInfo.nativeDataFormatCount > 0 && fullInfo.nativeDataFormats[0].sampleRate > 0)
@@ -131,6 +134,15 @@ bool MiniAudioSource::open() {
         return false;
     }
 
+    // Read back actual device parameters (the backend may give us fewer
+    // channels than requested, e.g. Web Audio defaults to mono).
+    channels_   = static_cast<int>(device_->capture.channels);
+    sampleRate_ = static_cast<double>(device_->sampleRate);
+
+    // Rebuild ring buffer to match actual channel count.
+    size_t ringSize = static_cast<size_t>(sampleRate_ * channels_ * 2);
+    ringBuf_ = std::make_unique<RingBuffer<float>>(ringSize);
+
     if (ma_device_start(device_.get()) != MA_SUCCESS) {
         std::fprintf(stderr, "miniaudio: failed to start device\n");
         ma_device_uninit(device_.get());

src/audio/miniaudio.h

@@ -41906,7 +41906,8 @@ static void ma_audio_worklet_processor_created__webaudio(EMSCRIPTEN_WEBAUDIO_T a
             var audioWorklet = emscriptenGetAudioObject($0);
             var audioContext = emscriptenGetAudioObject($1);
 
-            navigator.mediaDevices.getUserMedia({audio:true, video:false})
+            var reqCh = $2;
+            navigator.mediaDevices.getUserMedia({audio:{channelCount:{ideal:reqCh}}, video:false})
                 .then(function(stream) {
                     audioContext.streamNode = audioContext.createMediaStreamSource(stream);
                     audioContext.streamNode.connect(audioWorklet);
@@ -41919,7 +41920,7 @@ static void ma_audio_worklet_processor_created__webaudio(EMSCRIPTEN_WEBAUDIO_T a
                 });
 
             return getUserMediaResult;
-        }, pParameters->pDevice->webaudio.audioWorklet, audioContext);
+        }, pParameters->pDevice->webaudio.audioWorklet, audioContext, (int)pParameters->pConfig->capture.channels);
 
         if (attachmentResult != MA_SUCCESS) {
             ma_log_postf(ma_device_get_log(pParameters->pDevice), MA_LOG_LEVEL_ERROR, "Web Audio: Failed to connect capture node.");
@@ -42209,7 +42210,7 @@ static ma_result ma_device_init__webaudio(ma_device* pDevice, const ma_device_co
 
             /* Now we need to connect our node to the graph. */
             if (deviceType == window.miniaudio.device_type.capture || deviceType == window.miniaudio.device_type.duplex) {
-                navigator.mediaDevices.getUserMedia({audio:true, video:false})
+                navigator.mediaDevices.getUserMedia({audio:{channelCount:{ideal:channels}}, video:false})
                     .then(function(stream) {
                         device.streamNode = device.webaudio.createMediaStreamSource(stream);
                         device.streamNode.connect(device.scriptNode);

src/ui/Application.cpp

@@ -1128,7 +1128,7 @@ void Application::openPortAudio() {
     auto src = std::make_unique<MiniAudioSource>(sr, reqCh, deviceIdx);
     if (src->open()) {
         audioSource_ = std::move(src);
-        settings_.sampleRate = sr;
+        settings_.sampleRate = audioSource_->sampleRate();
         settings_.isIQ = false;
         settings_.numChannels = audioSource_->channels();
     } else {