Exposing RtpSenders and RtpReceivers from PeerConnection.

talk/app/webrtc/rtpreceiver.cc

+/*
+ * libjingle
+ * Copyright 2015 Google Inc.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *  1. Redistributions of source code must retain the above copyright notice,
+ *     this list of conditions and the following disclaimer.
+ *  2. Redistributions in binary form must reproduce the above copyright notice,
+ *     this list of conditions and the following disclaimer in the documentation
+ *     and/or other materials provided with the distribution.
+ *  3. The name of the author may not be used to endorse or promote products
+ *     derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
+ * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
+ * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+ * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
+ * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "talk/app/webrtc/rtpreceiver.h"
+
+#include "talk/app/webrtc/videosourceinterface.h"
+
+namespace webrtc {
+
+AudioRtpReceiver::AudioRtpReceiver(AudioTrackInterface* track,
+                                   uint32 ssrc,
+                                   AudioProviderInterface* provider)
+    : track_(track),
+      ssrc_(ssrc),
+      provider_(provider),
+      cached_track_enabled_(track->enabled()) {
+  track_->RegisterObserver(this);
+  track_->GetSource()->RegisterAudioObserver(this);
+  UpdateProvider();
+}
+
+AudioRtpReceiver::~AudioRtpReceiver() {
+  track_->GetSource()->UnregisterAudioObserver(this);
+  track_->UnregisterObserver(this);
+  if (provider_) {
+    DetachFromProvider();
+  }
+}
+
+void AudioRtpReceiver::OnChanged() {
+  if (cached_track_enabled_ != track_->enabled()) {
+    cached_track_enabled_ = track_->enabled();
+    UpdateProvider();
+  }
+}
+
+void AudioRtpReceiver::OnSetVolume(double volume) {
+  // When the track is disabled, the volume of the source, which is the
+  // corresponding WebRtc Voice Engine channel will be 0. So we do not allow
+  // setting the volume to the source when the track is disabled.
+  if (provider_ && track_->enabled())
+    provider_->SetAudioPlayoutVolume(ssrc_, volume);
+}
+
+void AudioRtpReceiver::DetachFromProvider() {
+  provider_->SetAudioPlayout(ssrc_, false, nullptr);

[pthatcher1, 2015/09/23 14:47:39]

If you put 

if (!provider_) {
  return;
}

At the beginning, it will be more safe and you won't have to check it everywhere
else.  You can just call Stop().

And the same idea for all of (Audio, Video)(Sender, Receiver).

[pthatcher1, 2015/09/24 06:32:29]

I still think this is a good idea.

+  provider_ = nullptr;
+}
+
+void AudioRtpReceiver::UpdateProvider() {

[pthatcher1, 2015/09/23 14:47:39]

I think that it would make sense to call this something like Reconfigure(). 
Right now that means going through the provider.  In the future, it will do
something else.  Might as well not have "provider" in the name.

And the same idea for all of (Audio, Video)(Sender, Receiver).

[pthatcher1, 2015/09/24 06:32:29]

I still think this is a good idea.

+  if (!provider_) {
+    return;
+  }
+  provider_->SetAudioPlayout(ssrc_, track_->enabled(), track_->GetRenderer());
+}
+
+VideoRtpReceiver::VideoRtpReceiver(VideoTrackInterface* track,
+                                   uint32 ssrc,
+                                   VideoProviderInterface* provider)
+    : track_(track), ssrc_(ssrc), provider_(provider) {
+  provider_->SetVideoPlayout(ssrc_, true, track_->GetSource()->FrameInput());
+}
+
+VideoRtpReceiver::~VideoRtpReceiver() {
+  if (provider_) {
+    // Since cricket::VideoRenderer is not reference counted,
+    // we need to remove it from the provider before we are deleted.
+    DetachFromProvider();
+  }
+}
+
+void VideoRtpReceiver::DetachFromProvider() {
+  provider_->SetVideoPlayout(ssrc_, false, nullptr);
+  provider_ = nullptr;
+}
+
+}  // namespace webrtc