Propagate muted info from VoE Channel to AudioConferenceMixer

webrtc/voice_engine/voe_external_media_impl.cc

 /*
  *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 135 matching lines @@
         "GetAudioFrame() was called on channel that is not playing.");
     return -1;
   }
   if (desired_sample_rate_hz == -1) {
     shared_->SetLastError(VE_BAD_ARGUMENT, kTraceError,
                           "GetAudioFrame() was called with bad sample rate.");
     return -1;
   }
   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) {
   WEBRTC_TRACE(kTraceApiCall, kTraceVoice,
                VoEId(shared_->instance_id(), channel),
                "SetExternalMixing(channel=%d, enable=%d)", channel, enable);
   if (!shared_->statistics().Initialized()) {
     shared_->SetLastError(VE_NOT_INITED, kTraceError);
     return -1;
   }
   voe::ChannelOwner ch = shared_->channel_manager().GetChannel(channel);
   voe::Channel* channelPtr = ch.channel();
   if (channelPtr == NULL) {
     shared_->SetLastError(VE_CHANNEL_NOT_VALID, kTraceError,
                           "SetExternalMixing() failed to locate channel");
     return -1;
   }
   return channelPtr->SetExternalMixing(enable);
 }
 
 #endif  // WEBRTC_VOICE_ENGINE_EXTERNAL_MEDIA_API
 
 }  // namespace webrtc