[Experiment] Alpha Channel Support

examples/unityplugin/simple_peer_connection.cc

Index: examples/unityplugin/simple_peer_connection.cc
diff --git a/examples/unityplugin/simple_peer_connection.cc b/examples/unityplugin/simple_peer_connection.cc
index fe59d53a6f5728517762300d0f2a60ff546f398e..80f8ee7af7698a7d1c9fc1776614fe475053a371 100644
--- a/examples/unityplugin/simple_peer_connection.cc
+++ b/examples/unityplugin/simple_peer_connection.cc
@@ -74,6 +74,23 @@ class DummySetSessionDescriptionObserver
   ~DummySetSessionDescriptionObserver() {}
 };
 
+class DummyCapturer : public cricket::VideoCapturer {
+ public:
+  cricket::CaptureState Start(
+      const cricket::VideoFormat& capture_format) override {
+    return cricket::CS_RUNNING;
+  }
+  void Stop() override {}
+  void AddOrUpdateSink(rtc::VideoSinkInterface<webrtc::VideoFrame>* sink,
+                       const rtc::VideoSinkWants& wants) override {}
+
+  bool IsRunning() override { return true; }
+  bool IsScreencast() const override { return false; }
+  bool GetPreferredFourccs(std::vector<uint32_t>* fourccs) override {
+    return true;
+  }
+};
+
 }  // namespace
 
 bool SimplePeerConnection::InitializePeerConnection(const char** turn_urls,
@@ -211,7 +228,6 @@ void SimplePeerConnection::OnSuccess(
 
   std::string sdp;
   desc->ToString(&sdp);
-
   if (OnLocalSdpReady)
     OnLocalSdpReady(desc->type().c_str(), sdp.c_str());
 }
@@ -407,7 +423,6 @@ void SimplePeerConnection::AddStreams(bool audio_only) {
   std::string id = audio_track->id();
   stream->AddTrack(audio_track);
 
-  if (!audio_only) {
 #if defined(WEBRTC_ANDROID)
     JNIEnv* env = webrtc::jni::GetEnv();
     jclass pc_factory_class =
@@ -421,43 +436,50 @@ void SimplePeerConnection::AddStreams(bool audio_only) {
     RTC_DCHECK(texture_helper != nullptr)
         << "Cannot get the Surface Texture Helper.";
 
-    rtc::scoped_refptr<AndroidVideoTrackSource> source(
-        new rtc::RefCountedObject<AndroidVideoTrackSource>(
+    rtc::scoped_refptr<webrtc::jni::AndroidVideoTrackSource> source(
+        new rtc::RefCountedObject<webrtc::jni::AndroidVideoTrackSource>(
             g_signaling_thread.get(), env, texture_helper, false));
     rtc::scoped_refptr<webrtc::VideoTrackSourceProxy> proxy_source =
         webrtc::VideoTrackSourceProxy::Create(g_signaling_thread.get(),
                                               g_worker_thread.get(), source);
 
-    // link with VideoCapturer (Camera);
-    jmethodID link_camera_method = webrtc::jni::GetStaticMethodID(
-        env, pc_factory_class, "LinkCamera",
-        "(JLorg/webrtc/SurfaceTextureHelper;)Lorg/webrtc/VideoCapturer;");
-    jobject camera_tmp =
-        env->CallStaticObjectMethod(pc_factory_class, link_camera_method,
-                                    (jlong)proxy_source.get(), texture_helper);
-    CHECK_EXCEPTION(env);
-    g_camera = (jobject)env->NewGlobalRef(camera_tmp);
+    if (!audio_only) {
+      // link with VideoCapturer (Camera);
+      jmethodID link_camera_method = webrtc::jni::GetStaticMethodID(
+          env, pc_factory_class, "LinkCamera",
+          "(JLorg/webrtc/SurfaceTextureHelper;)Lorg/webrtc/VideoCapturer;");
+      jobject camera_tmp = env->CallStaticObjectMethod(
+          pc_factory_class, link_camera_method, (jlong)proxy_source.get(),
+          texture_helper);
+      CHECK_EXCEPTION(env);
+      g_camera = (jobject)env->NewGlobalRef(camera_tmp);
+    }
 
     rtc::scoped_refptr<webrtc::VideoTrackInterface> video_track(
         g_peer_connection_factory->CreateVideoTrack(kVideoLabel,
                                                     proxy_source.release()));
     stream->AddTrack(video_track);
 #else
-    std::unique_ptr<cricket::VideoCapturer> capture = OpenVideoCaptureDevice();
-    if (capture) {
-      rtc::scoped_refptr<webrtc::VideoTrackInterface> video_track(
-          g_peer_connection_factory->CreateVideoTrack(
-              kVideoLabel, g_peer_connection_factory->CreateVideoSource(
-                               std::move(capture), nullptr)));
-
-      stream->AddTrack(video_track);
-    }
+  std::unique_ptr<cricket::VideoCapturer> capture;
+  if (!audio_only) {
+    capture = OpenVideoCaptureDevice();
+  } else {
+    capture.reset(new DummyCapturer());
+  }
+  if (capture) {
+    rtc::scoped_refptr<webrtc::VideoTrackInterface> video_track(
+        g_peer_connection_factory->CreateVideoTrack(
+            kVideoLabel, g_peer_connection_factory->CreateVideoSource(
+                             std::move(capture), nullptr)));
+
+    stream->AddTrack(video_track);
+  }
+
 #endif
     if (local_video_observer_ && !stream->GetVideoTracks().empty()) {
       stream->GetVideoTracks()[0]->AddOrUpdateSink(local_video_observer_.get(),
                                                    rtc::VideoSinkWants());
     }
-  }
 
   if (!peer_connection_->AddStream(stream)) {
     LOG(LS_ERROR) << "Adding stream to PeerConnection failed";