Add AudioReceiveStream::SetGain() method and use that in WVoMC::SetOutputVolume().

webrtc/media/engine/webrtcvoiceengine.cc

 /*
  *  Copyright (c) 2004 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 1245 matching lines @@
   int channel() const {
     RTC_DCHECK(worker_thread_checker_.CalledOnValidThread());
     return config_.voe_channel_id;
   }
 
   void SetRawAudioSink(std::unique_ptr<webrtc::AudioSinkInterface> sink) {
     RTC_DCHECK(worker_thread_checker_.CalledOnValidThread());
     stream_->SetSink(std::move(sink));
   }
 
+  void SetOutputVolume(double volume) {
+    RTC_DCHECK(worker_thread_checker_.CalledOnValidThread());
+    stream_->SetGain(volume);
+  }
+
  private:
   void RecreateAudioReceiveStream(
       bool use_transport_cc,
       const std::vector<webrtc::RtpExtension>& extensions) {
     RTC_DCHECK(worker_thread_checker_.CalledOnValidThread());
     if (stream_) {
       call_->DestroyAudioReceiveStream(stream_);
       stream_ = nullptr;
     }
     config_.rtp.extensions = extensions;
@@ skipping 921 matching lines @@
 
 bool WebRtcVoiceMediaChannel::SetOutputVolume(uint32_t ssrc, double volume) {
   RTC_DCHECK(worker_thread_checker_.CalledOnValidThread());
   if (ssrc == 0) {
     default_recv_volume_ = volume;
     if (default_recv_ssrc_ == -1) {
       return true;
     }
     ssrc = static_cast<uint32_t>(default_recv_ssrc_);
   }
-  int ch_id = GetReceiveChannelId(ssrc);
-  if (ch_id < 0) {
-    LOG(LS_WARNING) << "Cannot find channel for ssrc:" << ssrc;
+  const auto it = recv_streams_.find(ssrc);
+  if (it == recv_streams_.end()) {
+    LOG(LS_WARNING) << "SetOutputVolume: no recv stream" << ssrc;
     return false;
   }
-
-  if (-1 == engine()->voe()->volume()->SetChannelOutputVolumeScaling(ch_id,
-                                                                     volume)) {
-    LOG_RTCERR2(SetChannelOutputVolumeScaling, ch_id, volume);
-    return false;
-  }
-  LOG(LS_INFO) << "SetOutputVolume to " << volume
-               << " for channel " << ch_id << " and ssrc " << ssrc;
+  it->second->SetOutputVolume(volume);
+  LOG(LS_INFO) << "SetOutputVolume() to " << volume
+               << " for recv channel with ssrc " << ssrc;

[kwiberg-webrtc, 2016/06/16 09:26:53]

"recv stream"?

[the sun, 2016/06/16 14:34:06]

Done.

   return true;
 }
 
 bool WebRtcVoiceMediaChannel::CanInsertDtmf() {
   return dtmf_payload_type_ ? true : false;
 }
 
 bool WebRtcVoiceMediaChannel::InsertDtmf(uint32_t ssrc, int event,
                                          int duration) {
   RTC_DCHECK(worker_thread_checker_.CalledOnValidThread());
@@ skipping 319 matching lines @@
     }
   } else {
     LOG(LS_INFO) << "Stopping playout for channel #" << channel;
     engine()->voe()->base()->StopPlayout(channel);
   }
   return true;
 }
 }  // namespace cricket
 
 #endif  // HAVE_WEBRTC_VOICE