Propagate muted info from VoE Channel to AudioConferenceMixer

webrtc/voice_engine/voe_external_media_impl.cc

Index: webrtc/voice_engine/voe_external_media_impl.cc
diff --git a/webrtc/voice_engine/voe_external_media_impl.cc b/webrtc/voice_engine/voe_external_media_impl.cc
index 7b2b6a00f1e1d8094724b64a87159733ba5f04ab..cae0715ced2da3af353f8784b2f4c11814da1a15 100644
--- a/webrtc/voice_engine/voe_external_media_impl.cc
+++ b/webrtc/voice_engine/voe_external_media_impl.cc
@@ -153,7 +153,11 @@ int VoEExternalMediaImpl::GetAudioFrame(int channel, int desired_sample_rate_hz,
   }
   frame->sample_rate_hz_ =
       desired_sample_rate_hz == 0 ? -1 : desired_sample_rate_hz;
-  return channelPtr->GetAudioFrame(channel, frame);
+  auto ret = channelPtr->GetAudioFrameWithMuted(channel, frame);
+  if (ret == MixerParticipant::AudioFrameInfo::kMuted) {
+    frame->Mute();

[minyue-webrtc, 2016/05/17 14:59:17]

I am confused, isn't this memset frame's samples to zeros? is this the end of
the story?

[hlundin-webrtc, 2016/05/17 19:57:51]

This is only the case in the VoEExternalMediaImpl, which is not part of our main
audio flow (iiuc). So, in this special case, it is the end of the story, but in
the "normal" case, the story ends in the AudioConferenceMixer, where the muted
information is used to avoid calculating energies, and in most cases not
generate any zero-samples.

[minyue-webrtc, 2016/05/18 01:31:30]

Acknowledged.

+  }
+  return ret == MixerParticipant::AudioFrameInfo::kError ? -1 : 0;
 }
 
 int VoEExternalMediaImpl::SetExternalMixing(int channel, bool enable) {