Made AudioReceiveStream a mixer participant.

webrtc/audio/audio_receive_stream.h

 /*
  *  Copyright (c) 2015 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.
  */
 
 #ifndef WEBRTC_AUDIO_AUDIO_RECEIVE_STREAM_H_
 #define WEBRTC_AUDIO_AUDIO_RECEIVE_STREAM_H_
 
 #include <memory>
 
 #include "webrtc/api/call/audio_receive_stream.h"
 #include "webrtc/api/call/audio_state.h"
 #include "webrtc/base/constructormagic.h"
 #include "webrtc/base/thread_checker.h"
 #include "webrtc/modules/rtp_rtcp/include/rtp_header_parser.h"
+#include "webrtc/modules/audio_mixer/audio_mixer_defines.h"
 
 namespace webrtc {
 class CongestionController;
 class RemoteBitrateEstimator;
 class RtcEventLog;
 
 namespace voe {
 class ChannelProxy;
 }  // namespace voe
 
 namespace internal {
 
-class AudioReceiveStream final : public webrtc::AudioReceiveStream {
+class AudioReceiveStream final : public webrtc::AudioReceiveStream,
+                                 public MixerAudioSource {

[the sun, 2016/10/03 11:41:26]

Multiple inheritance with implementation classes is a slippery slope. Can we
make MixerAudioSource a pure interface before we do this?

Also, the *public* mix_history_ *pointer* in MixerAudioSource is a dangerous
construct. It seems to me MixerAudioSource should be split up into a) the
interface and b) the object containing the mix state for AudioMixerImpl. The
latter would be internal to AudioMixerImpl.

[aleloi, 2016/10/03 12:57:28]

ossu@ has pointed out the naked pointer problems a while ago. I have made a CL
that removes mix_history_ a dependency. webrtc::AudioReceiveStream is a pure
interface, so this is strictly speaking a no-multiple-inheritance rule violation
(at least not yet).

Splitting MixerAudioSource in two would have consequence on the way participants
can find out if they are mixed or not. Now a participant can call
this->WasMixed(). If I remove that, the functionality could either be moved to
AudioMixer or maybe be dropped completely. I think it's better to remove it
completely since it's not used anywhere.

  public:
   AudioReceiveStream(CongestionController* congestion_controller,
                      const webrtc::AudioReceiveStream::Config& config,
                      const rtc::scoped_refptr<webrtc::AudioState>& audio_state,
                      webrtc::RtcEventLog* event_log);
   ~AudioReceiveStream() override;
 
   // webrtc::AudioReceiveStream implementation.
   void Start() override;
   void Stop() override;
   webrtc::AudioReceiveStream::Stats GetStats() const override;
   void SetSink(std::unique_ptr<AudioSinkInterface> sink) override;
   void SetGain(float gain) override;
 
   void SignalNetworkState(NetworkState state);
   bool DeliverRtcp(const uint8_t* packet, size_t length);
   bool DeliverRtp(const uint8_t* packet,
                   size_t length,
                   const PacketTime& packet_time);
   const webrtc::AudioReceiveStream::Config& config() const;
 
+  // MixerAudioSource
+  AudioFrameWithMuted GetAudioFrameWithMuted(int32_t id,
+                                             int sample_rate_hz) override;
+
  private:
   VoiceEngine* voice_engine() const;
 
   rtc::ThreadChecker thread_checker_;
   RemoteBitrateEstimator* remote_bitrate_estimator_ = nullptr;
   const webrtc::AudioReceiveStream::Config config_;
   rtc::scoped_refptr<webrtc::AudioState> audio_state_;
   std::unique_ptr<RtpHeaderParser> rtp_header_parser_;
   std::unique_ptr<voe::ChannelProxy> channel_proxy_;
 
   RTC_DISALLOW_IMPLICIT_CONSTRUCTORS(AudioReceiveStream);
 };
 }  // namespace internal
 }  // namespace webrtc
 
 #endif  // WEBRTC_AUDIO_AUDIO_RECEIVE_STREAM_H_