Restore ability to transmit in stereo.

gumble/gumbleopenal/stream.go

@@ -1064,21 +1064,10 @@ func (s *Stream) sourceRoutine(inputDevice *string, stop chan bool, done chan st
 					recorder.RecordAudioFrame(recorderOutgoingSource, outputBuffer, true)
 				}
 			} else if hasMicInput {
-				// Send mic when no file is playing. If the microphone is
-				// stereo, downmix to mono since Mumble voice transmission
-				// uses mono Opus encoding.
-				outBuf := int16Buffer
-				if s.sourceChannels == 2 {
-					monoBuf := make([]int16, frameSize)
-					for i := 0; i < frameSize; i++ {
-						// Average left and right channels
-						monoBuf[i] = int16((int32(int16Buffer[i*2]) + int32(int16Buffer[i*2+1])) / 2)
-					}
-					outBuf = monoBuf
-				}
-				outgoing <- gumble.AudioBuffer(outBuf)
+				// Preserve the capture device's channel layout for encoding.
+				outgoing <- gumble.AudioBuffer(int16Buffer)
 				if recorder := s.getRecorder(); recorder != nil {
-					recorder.RecordAudioFrame(recorderOutgoingSource, outBuf, false)
+					recorder.RecordAudioFrame(recorderOutgoingSource, int16Buffer, s.sourceChannels == 2)
 				}
 			}
 		}