Webrtc android代码结构分析

webrt 代码方面做了一下小的整理
1、依赖

    implementation 'org.webrtc:google-webrtc:1.0.+'
    implementation('io.socket:socket.io-client:0.8.3') {
        // excluding org.json which is provided by Android
        exclude group: 'org.json', module: 'json'
    }

2、权限

   <uses-permission android:name="android.permission.CAMERA"></uses-permission>
    <uses-permission android:name="android.permission.RECORD_AUDIO" />
    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
    <uses-permission android:name="android.permission.MODIFY_AUDIO_SETTINGS" />

3、webrtc代码部分
（1）初始化PeerConnectionFactory

   PeerConnectionFactory.InitializationOptions initializationOptions =
                PeerConnectionFactory.InitializationOptions.builder(this)
                        .setEnableVideoHwAcceleration(true)
                        .createInitializationOptions();
        PeerConnectionFactory.initialize(initializationOptions);

使用硬编解码

 //Create a new PeerConnectionFactory instance - using Hardware encoder and decoder.
        PeerConnectionFactory.Options options = new PeerConnectionFactory.Options();
        DefaultVideoEncoderFactory defaultVideoEncoderFactory = new DefaultVideoEncoderFactory(
                rootEglBase.getEglBaseContext(),  /* enableIntelVp8Encoder */true,  /* enableH264HighProfile */true);

        DefaultVideoDecoderFactory defaultVideoDecoderFactory = new DefaultVideoDecoderFactory(rootEglBase.getEglBaseContext());
        peerConnectionFactory = new PeerConnectionFactory(options, defaultVideoEncoderFactory, defaultVideoDecoderFactory);

（2）video Capturer——使用camera
webrtc 提供了开始捕获视频的步骤，因此你不需要知道camera的使用，通过webrtc调用就可以了

 VideoCapturer videoCapturerAndroid;
        videoCapturerAndroid = createCameraCapturer(new Camera1Enumerator(false));

createCameraCapturer（）方法——获取前置摄像头

  private VideoCapturer createCameraCapturer(CameraEnumerator enumerator) {
        final String[] deviceNames = enumerator.getDeviceNames();

        // First, try to find front facing camera
        Logging.d(TAG, "Looking for front facing cameras.");
        for (String deviceName : deviceNames) {
            if (enumerator.isFrontFacing(deviceName)) {
                Logging.d(TAG, "Creating front facing camera capturer.");
                VideoCapturer videoCapturer = enumerator.createCapturer(deviceName, null);

                if (videoCapturer != null) {
                    return videoCapturer;
                }
            }
        }

        // Front facing camera not found, try something else
        Logging.d(TAG, "Looking for other cameras.");
        for (String deviceName : deviceNames) {
            if (!enumerator.isFrontFacing(deviceName)) {
                Logging.d(TAG, "Creating other camera capturer.");
                VideoCapturer videoCapturer = enumerator.createCapturer(deviceName, null);

                if (videoCapturer != null) {
                    return videoCapturer;
                }
            }
        }

        return null;
    }

（3）Local media stream
在webrtc中，我们有media stream 媒体流的概念

  //Create MediaConstraints - Will be useful for specifying video and audio constraints.
        audioConstraints = new MediaConstraints(); //audio一些媒体限制，下面会用到
        videoConstraints = new MediaConstraints();//video一些媒体限制，暂时没用到，以前版本api会用到

        //Create a VideoSource instance
        if (videoCapturerAndroid != null) {
            videoSource = peerConnectionFactory.createVideoSource(videoCapturerAndroid);
        }
        localVideoTrack = peerConnectionFactory.createVideoTrack("100", videoSource);//100:VIDEO_TRACK_ID

        //create an AudioSource instance
        audioSource = peerConnectionFactory.createAudioSource(audioConstraints);
        localAudioTrack = peerConnectionFactory.createAudioTrack("101", audioSource);//101：AUDIO_TRACK_ID
  if (videoCapturerAndroid != null) {
            videoCapturerAndroid.startCapture(1024, 720, 30);
        }

添加stream track（audio/video track）

 private void addStreamToLocalPeer() {
        //creating local mediastream
        MediaStream stream = peerConnectionFactory.createLocalMediaStream("102");//102：LOCAL_STREAM_ID
        stream.addTrack(localAudioTrack);
        stream.addTrack(localVideoTrack);
        localPeer.addStream(stream);
    }

（4）使用SurfaceViewRenderer
有了上面几步，我们可以实现在本地预览，为了实现预览效果需要在移动端的布局中添加控件

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        android:id="@+id/activity_main"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_weight="1"
        android:orientation="vertical"
        tools:context="xyz.vivekc.webrtccodelab.MainActivity">


        <org.webrtc.SurfaceViewRenderer
            android:id="@+id/remote_gl_surface_view"
            android:layout_width="match_parent"
            android:layout_weight="1"
            android:visibility="gone"
            android:layout_height="match_parent" />

        <org.webrtc.SurfaceViewRenderer
            android:id="@+id/local_gl_surface_view"
            android:layout_width="match_parent"
            android:layout_gravity="bottom|end"
            android:layout_height="match_parent" />
    </FrameLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom"
        android:orientation="horizontal">
        <Button
            android:layout_width="wrap_content"
            android:layout_margin="5dp"
            android:layout_height="wrap_content"
            android:id="@+id/end_call"
            android:text="Hangup" />
    </LinearLayout>
</FrameLayout>

代码

 SurfaceViewRenderer localVideoView;
 SurfaceViewRenderer remoteVideoView;

private void initVideos() {
        rootEglBase = EglBase.create();
        localVideoView.init(rootEglBase.getEglBaseContext(), null);
        remoteVideoView.init(rootEglBase.getEglBaseContext(), null);
        localVideoView.setZOrderMediaOverlay(true);
        remoteVideoView.setZOrderMediaOverlay(true);
    }

 localVideoView.setVisibility(View.VISIBLE);
        //create a videoRenderer based on SurfaceViewRenderer instance
        localRenderer = new VideoRenderer(localVideoView);
        // And finally, with our VideoRenderer ready, we
        // can add our renderer to the VideoTrack.
        localVideoTrack.addRenderer(localRenderer);

        localVideoView.setMirror(true);
        remoteVideoView.setMirror(true);

（5）PeerConnection
为了创建peerconnection 我们需要提供stun 和turn server

  List<PeerConnection.IceServer> peerIceServers = new ArrayList<>();

iceserver

  private void initIceServer(){
        //add stun
        PeerConnection.IceServer stunpeerIceServer = PeerConnection.IceServer.builder("stun:stun.l.google.com:19302").createIceServer();
        peerIceServers.add(stunpeerIceServer);
        //add turn
        PeerConnection.IceServer turnpeerIceServer = PeerConnection.IceServer.builder("turn:turn.tokbox.com:443")
                .setUsername("user")
                .setPassword("pass")
                .createIceServer();
        peerIceServers.add(turnpeerIceServer);

    }

4、SDP 会话
（1）跟js api中的基本一样
（2）这里需要实现PeerConnectionObserver 和SDPObserver
（3）SDP over socket.IO
（4）这是媒体流的最后一步
（5）记得添加你的renderer

PeerConnectionObserver

class CustomPeerConnectionObserver implements PeerConnection.Observer {

    private String logTag;

    CustomPeerConnectionObserver(String logTag) {
        this.logTag = this.getClass().getCanonicalName();
        this.logTag = this.logTag+" "+logTag;
    }

    @Override
    public void onSignalingChange(PeerConnection.SignalingState signalingState) {
        Log.d(logTag, "onSignalingChange() called with: signalingState = [" + signalingState + "]");
    }

    @Override
    public void onIceConnectionChange(PeerConnection.IceConnectionState iceConnectionState) {
        Log.d(logTag, "onIceConnectionChange() called with: iceConnectionState = [" + iceConnectionState + "]");
    }

    @Override
    public void onIceConnectionReceivingChange(boolean b) {
        Log.d(logTag, "onIceConnectionReceivingChange() called with: b = [" + b + "]");
    }

    @Override
    public void onIceGatheringChange(PeerConnection.IceGatheringState iceGatheringState) {
        Log.d(logTag, "onIceGatheringChange() called with: iceGatheringState = [" + iceGatheringState + "]");
    }

    @Override
    public void onIceCandidate(IceCandidate iceCandidate) {
        Log.d(logTag, "onIceCandidate() called with: iceCandidate = [" + iceCandidate + "]");
    }

    @Override
    public void onIceCandidatesRemoved(IceCandidate[] iceCandidates) {
        Log.d(logTag, "onIceCandidatesRemoved() called with: iceCandidates = [" + iceCandidates + "]");
    }

    @Override
    public void onAddStream(MediaStream mediaStream) {
        Log.d(logTag, "onAddStream() called with: mediaStream = [" + mediaStream + "]");
    }

    @Override
    public void onRemoveStream(MediaStream mediaStream) {
        Log.d(logTag, "onRemoveStream() called with: mediaStream = [" + mediaStream + "]");
    }

    @Override
    public void onDataChannel(DataChannel dataChannel) {
        Log.d(logTag, "onDataChannel() called with: dataChannel = [" + dataChannel + "]");
    }

    @Override
    public void onRenegotiationNeeded() {
        Log.d(logTag, "onRenegotiationNeeded() called");
    }

    @Override
    public void onAddTrack(RtpReceiver rtpReceiver, MediaStream[] mediaStreams) {
        Log.d(logTag, "onAddTrack() called with: rtpReceiver = [" + rtpReceiver + "], mediaStreams = [" + mediaStreams + "]");
    }
}

SDPObserver

class CustomSdpObserver implements SdpObserver {


    private String tag;

    CustomSdpObserver(String logTag) {
        tag = this.getClass().getCanonicalName();
        this.tag = this.tag + " " + logTag;
    }


    @Override
    public void onCreateSuccess(SessionDescription sessionDescription) {
        Log.d(tag, "onCreateSuccess() called with: sessionDescription = [" + sessionDescription + "]");
    }

    @Override
    public void onSetSuccess() {
        Log.d(tag, "onSetSuccess() called");
    }

    @Override
    public void onCreateFailure(String s) {
        Log.d(tag, "onCreateFailure() called with: s = [" + s + "]");
    }

    @Override
    public void onSetFailure(String s) {
        Log.d(tag, "onSetFailure() called with: s = [" + s + "]");
    }

}