Avoid clicks when muting/unmuting a voe::Channel.

webrtc/voice_engine/transmit_mixer.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 341 matching lines @@
     if (swap_stereo_channels_ && stereo_codec_)
       // Only bother swapping if we're using a stereo codec.
       AudioFrameOperations::SwapStereoChannels(&_audioFrame);
 
     // --- Annoying typing detection (utilizes the APM/VAD decision)
 #ifdef WEBRTC_VOICE_ENGINE_TYPING_DETECTION
     TypingDetection(keyPressed);
 #endif
 
     // --- Mute signal
-    if (_mute)
-    {
-        AudioFrameOperations::Mute(_audioFrame);
-    }

[peah-webrtc, 2016/03/24 07:04:54]

Sorry for the late comment on this, but why is there no fading added in transmit
mixer? Or was that what was to be added in another CL?

[the sun, 2016/03/24 09:33:15]

Exactly.

+    AudioFrameOperations::Mute(&_audioFrame, _mute, _mute);
 
     // --- Mix with file (does not affect the mixing frequency)
     if (_filePlaying)
     {
         MixOrReplaceAudioWithFile(_audioFrame.sample_rate_hz_);
     }
 
     // --- Record to file
     bool file_recording = false;
     {
@@ skipping 928 matching lines @@
 void TransmitMixer::EnableStereoChannelSwapping(bool enable) {
   swap_stereo_channels_ = enable;
 }
 
 bool TransmitMixer::IsStereoChannelSwappingEnabled() {
   return swap_stereo_channels_;
 }
 
 }  // namespace voe
 }  // namespace webrtc