录制原理

• 预览

通过fbo处理视频数据,通过samplerExternalOES纹理来创建SurfaceTexture,这样的话摄像头数据就和fbo相关联，具体可以看OpenGLES通过SurfaceTexture预览摄像头画面

• 录制

通过MediaCodec创建一个surface，然后通过创建一个新的egl环境共享预览的EglContext和这个surface绑定，渲染fbo绑定的纹理，即可录制。
egl环境配置：
Android配置EGL环境
Android自定义GLSurfaceView

流程如下图所示:

录制原理

MediaCodec录制主要代码

 private MediaMuxer mMediaMuxer;
 private MediaCodec.BufferInfo mBuffInfo;
 private MediaCodec mVideoEncodec;
 private int width, height;


  //初始化
 public void initEncoder(EGLContext eglContext,String savePath,String mineType,int width,int height){
        this.width = width;
        this.height = height;
        this.mEGLContext = eglContext;
        initMediaEncoder(savePath,mineType,width,height);
    }

    private void initMediaEncoder(String savePath, String mineType, int width, int height) {
        try {
            mMediaMuxer = new MediaMuxer(savePath,MediaMuxer.OutputFormat.MUXER_OUTPUT_MPEG_4);
            initVideoEncoder(mineType,width,height);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private void initVideoEncoder(String mineType, int width, int height) {
        try {
            mVideoEncodec= MediaCodec.createEncoderByType(mineType);

            MediaFormat videoFormat = MediaFormat.createVideoFormat(mineType,width,height);
            videoFormat.setInteger(MediaFormat.KEY_COLOR_FORMAT, MediaCodecInfo.CodecCapabilities.COLOR_FormatSurface);
            videoFormat.setInteger(MediaFormat.KEY_FRAME_RATE,30);//30帧
            videoFormat.setInteger(MediaFormat.KEY_BIT_RATE,width*height*4);//RGBA
            videoFormat.setInteger(MediaFormat.KEY_BIT_RATE,width*height*4);//RGBA
            //设置压缩等级  默认是baseline
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
                videoFormat.setInteger(MediaFormat.KEY_PROFILE,MediaCodecInfo.CodecProfileLevel.AVCProfileMain);
                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
                    videoFormat.setInteger(MediaFormat.KEY_LEVEL, MediaCodecInfo.CodecProfileLevel.AVCLevel3);
                }
            }

            mVideoEncodec.configure(videoFormat,null,null,MediaCodec.CONFIGURE_FLAG_ENCODE);

            mBuffInfo = new MediaCodec.BufferInfo();
            mSurface = mVideoEncodec.createInputSurface();
        } catch (IOException e) {
            e.printStackTrace();
            mVideoEncodec=null;
            mBuffInfo=null;
            mSurface=null;
        }
    }


//开始录制
 public void startRecode(){
    videoEncodec.start();
    int outputBufferIndex = videoEncodec.dequeueOutputBuffer(videoBufferinfo, 0);
    if (outputBufferIndex == MediaCodec.INFO_OUTPUT_FORMAT_CHANGED) {
        videoTrackIndex = mediaMuxer.addTrack(videoEncodec.getOutputFormat());
        mediaMuxer.start();
    }else {
        while (outputBufferIndex>=0){
            ByteBuffer outputBuffer= videoEncodec.getOutputBuffers()[outputBufferIndex];
            outputBuffer.position(videoBufferinfo.offset);
            outputBuffer.limit(videoBufferinfo.offset + videoBufferinfo.size);

            //设置时间戳
            if(pts==0){
                pts = videoBufferinfo.presentationTimeUs;
            }
            videoBufferinfo.presentationTimeUs = videoBufferinfo.presentationTimeUs - pts;
            //写入数据
            mediaMuxer.writeSampleData(videoTrackIndex,outputBuffer,videoBufferinfo);
            if(encoderWeakReference.get().onMediaInfoListener!=null){
                encoderWeakReference.get().onMediaInfoListener.onMediaTime((int) (videoBufferinfo.presentationTimeUs/1000000));
            }
            videoEncodec.releaseOutputBuffer(outputBufferIndex,false);
            outputBufferIndex = videoEncodec.dequeueOutputBuffer(videoBufferinfo, 0);
        }
    }
 }
 
//停止录制
public void stopRecode(){
    videoEncodec.stop();
    videoEncodec.release();
    videoEncodec =null;

    mediaMuxer.stop();
    mediaMuxer.release();
    mediaMuxer = null;
}

具体示例请看:
https://github.com/ChinaZeng/SurfaceRecodeDemo