Prevent a voice channel from sending data before a renderer is set.

webrtc/media/engine/webrtcvoiceengine.cc

Index: webrtc/media/engine/webrtcvoiceengine.cc
diff --git a/webrtc/media/engine/webrtcvoiceengine.cc b/webrtc/media/engine/webrtcvoiceengine.cc
index 28c50793aa3518cefa4fe35ca073e4f474022642..e0f1011457965136dccb9c3d1337244889381b26 100644
--- a/webrtc/media/engine/webrtcvoiceengine.cc
+++ b/webrtc/media/engine/webrtcvoiceengine.cc
@@ -1158,7 +1158,7 @@ class WebRtcVoiceMediaChannel::WebRtcAudioSendStream
 
   ~WebRtcAudioSendStream() override {
     RTC_DCHECK(worker_thread_checker_.CalledOnValidThread());
-    Stop();
+    StopRendering();
     call_->DestroyAudioSendStream(stream_);
   }
 
@@ -1188,11 +1188,16 @@ class WebRtcVoiceMediaChannel::WebRtcAudioSendStream
     return stream_->GetStats();
   }
 
+  bool IsRendering() const {
+    RTC_DCHECK(worker_thread_checker_.CalledOnValidThread());
+    return renderer_ != nullptr;
+  }
+
   // Starts the rendering by setting a sink to the renderer to get data
   // callback.
   // This method is called on the libjingle worker thread.
   // TODO(xians): Make sure Start() is called only once.
-  void Start(AudioRenderer* renderer) {
+  void StartRendering(AudioRenderer* renderer) {
     RTC_DCHECK(worker_thread_checker_.CalledOnValidThread());
     RTC_DCHECK(renderer);
     if (renderer_) {
@@ -1206,7 +1211,7 @@ class WebRtcVoiceMediaChannel::WebRtcAudioSendStream
   // Stops rendering by setting the sink of the renderer to nullptr. No data
   // callback will be received after this method.
   // This method is called on the libjingle worker thread.
-  void Stop() {
+  void StopRendering() {
     RTC_DCHECK(worker_thread_checker_.CalledOnValidThread());
     if (renderer_) {
       renderer_->SetSink(nullptr);
@@ -1830,8 +1835,8 @@ bool WebRtcVoiceMediaChannel::ChangeSend(SendFlags send) {
   }
 
   // Change the settings on each send channel.
-  for (const auto& ch : send_streams_) {
-    if (!ChangeSend(ch.second->channel(), send)) {
+  for (const auto& kv : send_streams_) {
+    if (!UpdateChannelSendState(kv.first, send)) {
       return false;
     }
   }
@@ -1840,14 +1845,23 @@ bool WebRtcVoiceMediaChannel::ChangeSend(SendFlags send) {
   return true;
 }
 
-bool WebRtcVoiceMediaChannel::ChangeSend(int channel, SendFlags send) {
-  if (send == SEND_MICROPHONE) {
+bool WebRtcVoiceMediaChannel::UpdateChannelSendState(uint32_t ssrc,
+                                                     SendFlags send) {
+  RTC_DCHECK(send == SEND_NOTHING || send == SEND_MICROPHONE);
+
+  auto it = send_streams_.find(ssrc);
+  if (it == send_streams_.end()) {
+    RTC_DCHECK(false && "UpdateChannelSendState called with invalid SSRC.");
+    return false;
+  }
+
+  int channel = it->second->channel();
+  if (send == SEND_MICROPHONE && it->second->IsRendering()) {
     if (engine()->voe()->base()->StartSend(channel) == -1) {
       LOG_RTCERR1(StartSend, channel);
       return false;
     }
-  } else {  // SEND_NOTHING
-    RTC_DCHECK(send == SEND_NOTHING);
+  } else {  // SEND_NOTHING || !it->second->IsRendering()
     if (engine()->voe()->base()->StopSend(channel) == -1) {
       LOG_RTCERR1(StopSend, channel);
       return false;
@@ -1870,6 +1884,11 @@ bool WebRtcVoiceMediaChannel::SetAudioSend(uint32_t ssrc,
   if (!MuteStream(ssrc, !enable)) {
     return false;
   }
+  // If the renderer was set or unset we may need to update the sending
+  // state of the voe::Channel.
+  if (!UpdateChannelSendState(ssrc, send_)) {
+    return false;
+  }
   if (enable && options) {
     return SetOptions(*options);
   }
@@ -1951,7 +1970,7 @@ bool WebRtcVoiceMediaChannel::AddSendStream(const StreamParams& sp) {
     }
   }
 
-  return ChangeSend(channel, desired_send_);

[Taylor Brandstetter, 2016/03/02 21:53:53]

I changed this from desired_send_ to send_, because it seems like if the
MediaChannel is "paused" and you add a new channel, it should start out paused
as well.

+  return UpdateChannelSendState(ssrc, send_);
 }
 
 bool WebRtcVoiceMediaChannel::RemoveSendStream(uint32_t ssrc) {
@@ -1965,10 +1984,10 @@ bool WebRtcVoiceMediaChannel::RemoveSendStream(uint32_t ssrc) {
     return false;
   }
 
-  int channel = it->second->channel();
-  ChangeSend(channel, SEND_NOTHING);
+  UpdateChannelSendState(ssrc, SEND_NOTHING);
 
   // Clean up and delete the send stream+channel.
+  int channel = it->second->channel();
   LOG(LS_INFO) << "Removing audio send stream " << ssrc
                << " with VoiceEngine channel #" << channel << ".";
   delete it->second;
@@ -2103,9 +2122,9 @@ bool WebRtcVoiceMediaChannel::SetLocalRenderer(uint32_t ssrc,
   }
 
   if (renderer) {
-    it->second->Start(renderer);
+    it->second->StartRendering(renderer);
   } else {
-    it->second->Stop();
+    it->second->StopRendering();
   }
 
   return true;