Android设备之间投屏功能实现

简介

简单实现两个android设备之间的投屏功能。设备间通信是通过局域网，需要连接同一个wifi。

录屏用到系统的MediaProjection，MediaProjectionManager，而编解码用的是MediaCodec，所以设备需要有DSP芯片，大部分手机应该都有。两台设备间通信使用websocket，录屏端作为服务器进行推流，显示端就是客户端，收到码流进行解码并显示。

先看看最终效果：

在这里插入图片描述

实现

首先需要先导入Java-WebSocket库,WebSocket是一种在单个TCP连接上进行全双工通信的协议,允许服务端主动向客户端推送数据。

implementation "org.java-websocket:Java-WebSocket:1.4.0"

整个工程有两个module，app是作为服务端。playscreen是客户端。需要分别运行在两台机器上面。

在这里插入图片描述

服务端 app module

MainActivity 就一个button布局就不贴出来了。

import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;
import android.content.Intent;
import android.media.projection.MediaProjection;
import android.media.projection.MediaProjectionManager;
import android.os.Bundle;
import android.view.View;
import com.example.castscreen.socket.SocketService;public class MainActivity extends AppCompatActivity {private int permissionRequestCode = 100;private int captureRequestCode = 1;private MediaProjectionManager mediaProjectionManager;private SocketService socketService;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);init();}private void init() {//拿到MediaProjectionManagermediaProjectionManager = (MediaProjectionManager) getSystemService(MEDIA_PROJECTION_SERVICE);}public void onClick(View view) {switch (view.getId()){case R.id.btn_start:startCast();break;}}//请求开始录屏private void startCast(){PermissionUtil.checkPermission(this,PermissionUtil.storagePermissions,permissionRequestCode);Intent intent = mediaProjectionManager.createScreenCaptureIntent();startActivityForResult(intent,captureRequestCode);}@Overrideprotected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {super.onActivityResult(requestCode, resultCode, data);if (resultCode != RESULT_OK){return;}if(requestCode == this.captureRequestCode){startCast(resultCode,data);}}//录屏开始后进行编码推流private void startCast(int resultCode,Intent data){//这里需要传入resultCode而不是requestCode，在这里踩了个坑大家注意MediaProjection mediaProjection = mediaProjectionManager.getMediaProjection(resultCode,data);if (mediaProjection == null){return;}//初始化服务器端socketService = new SocketService();//将MediaProjection传给 socketService socketService.start(mediaProjection);}@Overrideprotected void onDestroy() {super.onDestroy();if (socketService != null){socketService.colse();}}
}

SocketService 作用是启动SocketServer并设置端口号。启动CodecH265 进行编码，CodecH265 编码完一帧再通过SocketServer将数据发送出去。

import android.media.projection.MediaProjection;
import com.example.castscreen.encode.CodecH265;
import java.io.IOException;
import java.net.InetSocketAddress;public class SocketService {private static final String TAG = "SocketService";//端口号，尽量设大一些private int port = 11006;private CodecH265 codecH265;private SocketServer webSocketServer;public SocketService(){webSocketServer = new SocketServer(new InetSocketAddress(port));}public void start(MediaProjection mediaProjection){//启动webSocketServer  此时当前设备就可以作为一个服务器了webSocketServer.start();codecH265 = new CodecH265(this,mediaProjection);//开始编码codecH265.startEncode();}//关闭服务端public void colse(){try {webSocketServer.stop();webSocketServer.close();} catch (IOException e) {e.printStackTrace();} catch (InterruptedException e) {e.printStackTrace();}codecH265.stopEncode();}//发送编码后的数据public void sendData(byte[] bytes){webSocketServer.sendData(bytes);}
}

SocketServer 继承自WebSocketServer，调用它的start方法就启动服务端了。

import android.util.Log;
import org.java_websocket.WebSocket;
import org.java_websocket.handshake.ClientHandshake;
import org.java_websocket.server.WebSocketServer;
import java.net.InetSocketAddress;public class SocketServer extends WebSocketServer {private final String TAG = "SocketServer";private WebSocket webSocket;public SocketServer(InetSocketAddress inetSocketAddress){super(inetSocketAddress);}@Overridepublic void onOpen(WebSocket conn, ClientHandshake handshake) {Log.d(TAG,"SocketServer onOpen");this.webSocket = conn;}@Overridepublic void onClose(WebSocket conn, int code, String reason, boolean remote) {}@Overridepublic void onMessage(WebSocket conn, String message) {}@Overridepublic void onError(WebSocket conn, Exception ex) {}@Overridepublic void onStart() {}public void sendData(byte[] bytes){if(webSocket != null && webSocket.isOpen()){//通过WebSocket 发送数据webSocket.send(bytes);}}public void close(){webSocket.close();}
}

CodecH265是实现编码的类，这里用的是video/hevc，也就是H265编码。需要注意的是因为H265编码只有第一帧才有vps,sps,pps，其他帧不带这些信息，所以需要我们在发送时候为每个I帧添加上vps信息，否则如果客户端不是从头开始接受的数据，那么就没办法进行解码操作。而且H265用的是哥伦布编码，如果对reEncode方法有疑问可以先了解一下哥伦布编码。另外因为编码是比较耗时的操作，肯定要方法子线程中去做。

import android.hardware.display.DisplayManager;
import android.hardware.display.VirtualDisplay;
import android.media.MediaCodec;
import android.media.MediaCodecInfo;
import android.media.MediaFormat;
import android.media.projection.MediaProjection;
import android.util.Log;
import android.view.Surface;
import com.example.castscreen.socket.SocketService;
import java.io.IOException;
import java.nio.ByteBuffer;public class CodecH265 extends Thread {private static final String TAG = "gsy";//图省事宽高直接固定了private int width = 720;private int height = 1280;//h265编码private final String enCodeType = "video/hevc";private MediaCodec mediaCodec;private MediaProjection mediaProjection;private SocketService socketService;private boolean play = true;private long timeOut = 10000;//记录vps pps spsprivate byte[] vps_pps_sps;//I帧private final int NAL_I = 19;//vps帧private final int NAL_VPS = 32;public CodecH265(SocketService socketService, MediaProjection mediaProjection) {this.socketService = socketService;this.mediaProjection = mediaProjection;}public void startEncode() {//声明MediaFormat，创建视频格式。MediaFormat mediaFormat = MediaFormat.createVideoFormat(MediaFormat.MIMETYPE_VIDEO_HEVC, width, height);//描述视频格式的内容的颜色格式mediaFormat.setInteger(MediaFormat.KEY_COLOR_FORMAT, MediaCodecInfo.CodecCapabilities.COLOR_FormatSurface);//比特率（比特/秒）mediaFormat.setInteger(MediaFormat.KEY_BIT_RATE, width * height);//帧率mediaFormat.setInteger(MediaFormat.KEY_FRAME_RATE, 20);//I帧的频率mediaFormat.setInteger(MediaFormat.KEY_I_FRAME_INTERVAL, 1);try {//创建编码MediaCodec 类型是video/hevcmediaCodec = MediaCodec.createEncoderByType(enCodeType);//配置编码器mediaCodec.configure(mediaFormat, null, null, MediaCodec.CONFIGURE_FLAG_ENCODE);//创建一个目的surface来存放输入数据Surface surface = mediaCodec.createInputSurface();//获取屏幕流mediaProjection.createVirtualDisplay("screen", width, height, 1, DisplayManager.VIRTUAL_DISPLAY_FLAG_PUBLIC, surface, null, null);} catch (IOException e) {Log.d(TAG,"initEncode IOException");e.printStackTrace();}//启动子线程this.start();}@Overridepublic void run() {//编解码器立即进入刷新子状态mediaCodec.start();//缓存区的元数据MediaCodec.BufferInfo bufferInfo = new MediaCodec.BufferInfo();//子线程需要一直运行，进行编码推流，所以要一直循环while (play) {//查询编码输出int outPutBufferId = mediaCodec.dequeueOutputBuffer(bufferInfo, timeOut);if (outPutBufferId >= 0) {//获取编码之后的数据输出流队列ByteBuffer byteBuffer = mediaCodec.getOutputBuffer(outPutBufferId);//添加上vps,sps,ppsreEncode(byteBuffer, bufferInfo);//处理完成，释放ByteBuffer数据mediaCodec.releaseOutputBuffer(outPutBufferId, false);}}}private void reEncode(ByteBuffer byteBuffer, MediaCodec.BufferInfo bufferInfo) {//偏移4 00 00 00 01为分隔符需要跳过int offSet = 4;if (byteBuffer.get(2) == 0x01) {offSet = 3;}//计算出当前帧的类型int type = (byteBuffer.get(offSet) & 0x7E) >> 1;if (type == NAL_VPS) {//保存vps sps pps信息vps_pps_sps = new byte[bufferInfo.size];byteBuffer.get(vps_pps_sps);} else if (type == NAL_I) {//将保存的vps sps pps添加到I帧前final byte[] bytes = new byte[bufferInfo.size];byteBuffer.get(bytes);byte[] newBytes = new byte[vps_pps_sps.length + bytes.length];System.arraycopy(vps_pps_sps, 0, newBytes, 0, vps_pps_sps.length);System.arraycopy(bytes, 0, newBytes, vps_pps_sps.length, bytes.length);//将重新编码好的数据发送出去socketService.sendData(newBytes);} else {//B帧 P帧 直接发送byte[] bytes = new byte[bufferInfo.size];byteBuffer.get(bytes);socketService.sendData(bytes);}}public void stopEncode() {play = false;}}

客户端 playescreen module

客户端的页面只有一个SurfaceView，用来显示，布局代码就不贴了。MainActivity 实现了SocketServer.SocketCallback接口，当SocketServer收到数据后，通过回调将收到的码流传给MainActivity 进行解码渲染到SurfaceView。

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import android.media.MediaCodec;
import android.media.MediaFormat;
import android.os.Bundle;
import android.util.Log;
import android.view.Surface;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import java.io.IOException;
import java.nio.ByteBuffer;public class MainActivity extends AppCompatActivity implements SocketServer.SocketCallback{private static final String TAG = "gsy";private Surface surface;private SurfaceView surfaceView;private MediaCodec mediaCodec;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);init();}private void init() {surfaceView = findViewById(R.id.sfv_play);surfaceView.getHolder().addCallback(new SurfaceHolder.Callback() {@Overridepublic void surfaceCreated(@NonNull SurfaceHolder holder) {surface = holder.getSurface();//连接到服务端initSocket();//配置MediaCodecinitDecoder(surface);}@Overridepublic void surfaceChanged(@NonNull SurfaceHolder holder, int format, int width, int height) {}@Overridepublic void surfaceDestroyed(@NonNull SurfaceHolder holder) {}});}private void initDecoder(Surface surface) {try {//配置MediaFormat MediaCodecmediaCodec = MediaCodec.createDecoderByType(MediaFormat.MIMETYPE_VIDEO_HEVC);MediaFormat mediaFormat = MediaFormat.createVideoFormat(MediaFormat.MIMETYPE_VIDEO_HEVC,720,1280);mediaFormat.setInteger(MediaFormat.KEY_BIT_RATE,720*1280);mediaFormat.setInteger(MediaFormat.KEY_FRAME_RATE,20);mediaFormat.setInteger(MediaFormat.KEY_I_FRAME_INTERVAL,1);mediaCodec.configure(mediaFormat,surface,null,0);mediaCodec.start();} catch (IOException e) {Log.d(TAG,"initDecoder IOException ");e.printStackTrace();}}private void initSocket() {Log.d(TAG,"initSocket");//启动客户端SocketServer socketServer = new SocketServer();socketServer.setSocketCallback(this);socketServer.start();}@Overridepublic void callBack(byte[] data) {Log.d(TAG,"mainActivity callBack");//得到填充了有效数据的input buffer的索引int index = mediaCodec.dequeueInputBuffer(10000);if (index >= 0){//获取输入缓冲区ByteBuffer inputBuffer = mediaCodec.getInputBuffer(index);//清除原来的内容以接收新的内容inputBuffer.clear();inputBuffer.put(data,0,data.length);//将其提交给编解码器 把缓存数据入队mediaCodec.queueInputBuffer(index,0,data.length,System.currentTimeMillis(),0);}MediaCodec.BufferInfo bufferInfo = new MediaCodec.BufferInfo();//请求一个输出缓存int outputBufferIndex = mediaCodec.dequeueOutputBuffer(bufferInfo,10000);//直到outputBufferIndex < 0 才算处理完所有数据while (outputBufferIndex > 0){mediaCodec.releaseOutputBuffer(outputBufferIndex,true);outputBufferIndex = mediaCodec.dequeueOutputBuffer(bufferInfo,0);}}
}

SocketServer 就是客户端了，作用就是连接服务器，获取视频码流进行回调。注意ip地址不要，是服务端的ip地址，可以在设置中查看，比如：

在这里插入图片描述

import android.util.Log;
import org.java_websocket.client.WebSocketClient;
import org.java_websocket.handshake.ServerHandshake;
import java.net.URI;
import java.net.URISyntaxException;
import java.nio.ByteBuffer;public class SocketServer {private final String TAG = "gsy";private SocketClient socketClient;private SocketCallback socketCallback;//设置回调public void setSocketCallback(SocketCallback socketCallback){this.socketCallback = socketCallback;}public void start(){try {//这里要填服务端的ipURI uri = new URI("ws://192.168.1.103:11006");socketClient = new SocketClient(uri);socketClient.connect();} catch (URISyntaxException e) {Log.e(TAG,"error:"+e.toString());e.printStackTrace();}}private class SocketClient extends WebSocketClient{public SocketClient(URI serverUri) {super(serverUri);Log.d(TAG,"new SocketClient");}@Overridepublic void onOpen(ServerHandshake handshakedata) {Log.d(TAG,"SocketClient onOpen");}@Overridepublic void onMessage(String message) {Log.d(TAG,"onMessage");}@Overridepublic void onMessage(ByteBuffer bytes) {Log.d(TAG,"onMessage");//收到数据 进行回调byte[] buf = new byte[bytes.remaining()];bytes.get(buf);socketCallback.callBack(buf);}@Overridepublic void onClose(int code, String reason, boolean remote) {Log.d(TAG,"onClose ="+reason);}@Overridepublic void onError(Exception ex) {Log.d(TAG,"onerror ="+ex.toString());}}//回调public interface SocketCallback{void callBack(byte[] data);}
}