WebRTC做大疆无人机直播
大疆带屏遥控器有直播功能，用的是rtmp，但是延时有点大，所以在遥控器里安装自己的软件，用webrtc来做一个无人机视频实时传输。需要自定义一个VideoCapturer来获取无人机视频封装成便于webrtc使用的流。
1、自定义一个CapturerAircraft类来实现VideoCapturer接口
public class CapturerDefault implements VideoCapturer {
@Override
public void initialize(SurfaceTextureHelper surfaceTextureHelper, Context context, CapturerObserver capturerObserver) {
}
@Override
public void startCapture(int i, int i1, int i2) {
}
@Override
public void stopCapture() throws InterruptedException {
}
@Override
public void changeCaptureFormat(int i, int i1, int i2) {
}
@Override
public void dispose() {
}
@Override
public boolean isScreencast() {
return false;
}
}
2、构造函数传入DJICodecManager参数
public CapturerAircraft(DJICodecManager manager) {
dji_code_manager_ = manager;
dji_code_manager_.resetKeyFrame();
if (isM300Product()) {
OcuSyncLink ocuSyncLink = DJILogIn.getProductInstance().getAirLink().getOcuSyncLink();
// If your MutltipleLensCamera is set at right or top, you need to change the PhysicalSource to RIGHT_CAM or TOP_CAM.
ocuSyncLink.assignSourceToPrimaryChannel(PhysicalSource.LEFT_CAM, PhysicalSource.FPV_CAM, new CommonCallbacks.CompletionCallback() {
@Override
public void onResult(DJIError error) {
if (error == null) {
// showToast("assignSourceToPrimaryChannel success.");
} else {
// showToast("assignSourceToPrimaryChannel fail, reason: "+ error.getDescription());
}
}
});
}
}
public static boolean isM300Product() {
if (DJISDKManager.getInstance().getProduct() == null) {
return false;
}
Model model = DJISDKManager.getInstance().getProduct().getModel();
return model == Model.MATRICE_300_RTK;
}
3、initialize函数里面创建一个DJIYuvDataCallback实例
DJIYuvDataCallback的onYuvDataReceived函数用来接收每一帧的yuv数据，再实例化一个CapturerObserver对象，用来将无人机的视频捕获作为webrtc能使用的I420视频流
@Override
public void initialize(SurfaceTextureHelper surfaceTextureHelper, Context context, CapturerObserver capturerObserver) {
//For M300RTK, you need to actively request an I frame.
dji_yuv_data_callback_ = new DJIYuvDataCallback();
capturer_observer_ = capturerObserver;
}
private class DJIYuvDataCallback implements DJICodecManager.YuvDataCallback {
@Override
public void onYuvDataReceived(MediaFormat mediaFormat, ByteBuffer byteBuffer, int dataSize, int width, int height) {
if (is_rate_time) {
//is_rate_time = false;
JavaI420Buffer buffer = JavaI420Buffer.allocate(width, height);
ByteBuffer dataY = buffer.getDataY();
ByteBuffer dataU = buffer.getDataU();
ByteBuffer dataV = buffer.getDataV();
final byte[] bytes = new byte[dataSize];
byteBuffer.get(bytes);
int yLen = width * height;
int uLen = (width + 1) / 2 * ((height + 1) / 2);
int vLen = uLen;
int color_format = mediaFormat.getInteger(MediaFormat.KEY_COLOR_FORMAT);
switch (color_format) {
case MediaCodecInfo.CodecCapabilities.COLOR_FormatYUV420SemiPlanar:
//NV12
byte[] ubytes = new byte[uLen];
byte[] vbytes = new byte[vLen];
for (int i = 0; i < uLen; i++) {
ubytes[i] = bytes[yLen + 2 * i];
vbytes[i] = bytes[yLen + 2 * i + 1];
}
dataY.put(bytes, 0, yLen);
dataU.put(ubytes, 0, uLen);
dataV.put(vbytes, 0, vLen);
break;
case MediaCodecInfo.CodecCapabilities.COLOR_FormatYUV420Planar:
//YUV420P=I420
int yPos = 0;
int uPos = yPos + yLen;
int vPos = uPos + uLen;
dataY.put(bytes, yPos, yLen);
dataU.put(bytes, uPos, uLen);
dataV.put(bytes, vPos, vLen);
break;
default:
break;
}
long captureTimeNs = TimeUnit.MILLISECONDS.toNanos(SystemClock.elapsedRealtime());
VideoFrame videoFrame = new VideoFrame(buffer, 0, captureTimeNs);
capturer_observer_.onFrameCaptured(videoFrame);
videoFrame.release();
}
}
}
4、startCapture中用setYuvDataCallback设置yuv帧回调
@Override
public void startCapture(int width, int height, int framerate) {
this.frame_width_ = width;
this.frame_height_ = height;
this.frame_rate_ = framerate;
this.timer.schedule(this.tickTask, 0L, (long)(1000 / frame_rate_));
dji_code_manager_.enabledYuvData(true);
dji_code_manager_.setYuvDataCallback(dji_yuv_data_callback_);
}
以上就完成CapturerAircraft了，完整代码如下：
package com.example.livebroadcastfordrone;
import android.content.Context;
import android.media.MediaFormat;
import android.media.MediaCodecInfo;
import android.os.SystemClock;
import org.webrtc.CapturerObserver;
import org.webrtc.JavaI420Buffer;
import org.webrtc.SurfaceTextureHelper;
import org.webrtc.VideoCapturer;
import org.webrtc.VideoFrame;
import java.nio.ByteBuffer;
import java.util.Timer;
import java.util.TimerTask;
import java.util.concurrent.TimeUnit;
import dji.common.airlink.PhysicalSource;
import dji.common.error.DJIError;
import dji.common.product.Model;
import dji.common.util.CommonCallbacks;
import dji.sdk.airlink.OcuSyncLink;
import dji.sdk.codec.DJICodecManager;
import dji.sdk.sdkmanager.DJISDKManager;
public class CapturerAircraft implements VideoCapturer{
private DJICodecManager dji_code_manager_;
private DJIYuvDataCallback dji_yuv_data_callback_;
private CapturerObserver capturer_observer_;
private int frame_width_;
private int frame_height_;
private int frame_rate_;
private boolean is_rate_time = false;
private final Timer timer = new Timer();
private final TimerTask tickTask = new TimerTask() {
public void run() {
is_rate_time = true;
}
};
public CapturerAircraft(DJICodecManager manager) {
dji_code_manager_ = manager;
dji_code_manager_.resetKeyFrame();
if (isM300Product()) {
OcuSyncLink ocuSyncLink = DJILogIn.getProductInstance().getAirLink().getOcuSyncLink();
// If your MutltipleLensCamera is set at right or top, you need to change the PhysicalSource to RIGHT_CAM or TOP_CAM.
ocuSyncLink.assignSourceToPrimaryChannel(PhysicalSource.LEFT_CAM, PhysicalSource.FPV_CAM, new CommonCallbacks.CompletionCallback() {
@Override
public void onResult(DJIError error) {
if (error == null) {
// showToast("assignSourceToPrimaryChannel success.");
} else {
// showToast("assignSourceToPrimaryChannel fail, reason: "+ error.getDescription());
}
}
});
}
}
public static boolean isM300Product() {
if (DJISDKManager.getInstance().getProduct() == null) {
return false;
}
Model model = DJISDKManager.getInstance().getProduct().getModel();
return model == Model.MATRICE_300_RTK;
}
@Override
public void initialize(SurfaceTextureHelper surfaceTextureHelper, Context context, CapturerObserver capturerObserver) {
//For M300RTK, you need to actively request an I frame.
dji_yuv_data_callback_ = new DJIYuvDataCallback();
capturer_observer_ = capturerObserver;
}
private void checkNotDisposed() {
}
@Override
public void startCapture(int width, int height, int framerate) {
this.frame_width_ = width;
this.frame_height_ = height;
this.frame_rate_ = framerate;
this.timer.schedule(this.tickTask, 0L, (long)(1000 / frame_rate_));
dji_code_manager_.enabledYuvData(true);
dji_code_manager_.setYuvDataCallback(dji_yuv_data_callback_);
}
@Override
public void stopCapture() throws InterruptedException {
this.timer.cancel();
dji_code_manager_.enabledYuvData(false);
dji_code_manager_.setYuvDataCallback(null);
}
@Override
public void changeCaptureFormat(int width, int height, int framerate) {
}
@Override
public void dispose() {
}
@Override
public boolean isScreencast() {
return false;
}
private class DJIYuvDataCallback implements DJICodecManager.YuvDataCallback {
@Override
public void onYuvDataReceived(MediaFormat mediaFormat, ByteBuffer byteBuffer, int dataSize, int width, int height) {
if (is_rate_time) {
//is_rate_time = false;
JavaI420Buffer buffer = JavaI420Buffer.allocate(width, height);
ByteBuffer dataY = buffer.getDataY();
ByteBuffer dataU = buffer.getDataU();
ByteBuffer dataV = buffer.getDataV();
final byte[] bytes = new byte[dataSize];
byteBuffer.get(bytes);
int yLen = width * height;
int uLen = (width + 1) / 2 * ((height + 1) / 2);
int vLen = uLen;
int color_format = mediaFormat.getInteger(MediaFormat.KEY_COLOR_FORMAT);
switch (color_format) {
case MediaCodecInfo.CodecCapabilities.COLOR_FormatYUV420SemiPlanar:
//NV12
byte[] ubytes = new byte[uLen];
byte[] vbytes = new byte[vLen];
for (int i = 0; i < uLen; i++) {
ubytes[i] = bytes[yLen + 2 * i];
vbytes[i] = bytes[yLen + 2 * i + 1];
}
dataY.put(bytes, 0, yLen);
dataU.put(ubytes, 0, uLen);
dataV.put(vbytes, 0, vLen);
break;
case MediaCodecInfo.CodecCapabilities.COLOR_FormatYUV420Planar:
//YUV420P=I420
int yPos = 0;
int uPos = yPos + yLen;
int vPos = uPos + uLen;
dataY.put(bytes, yPos, yLen);
dataU.put(bytes, uPos, uLen);
dataV.put(bytes, vPos, vLen);
break;
default:
break;
}
long captureTimeNs = TimeUnit.MILLISECONDS.toNanos(SystemClock.elapsedRealtime());
VideoFrame videoFrame = new VideoFrame(buffer, 0, captureTimeNs);
capturer_observer_.onFrameCaptured(videoFrame);
videoFrame.release();
}
}
}
}
注：DJICodecManager实例要在主线程中创建