[RK3288][Android6.0] 一个例子看MediaCodec使用流程

Platform: Rockchip
OS: Android 6.0
Kernel: 3.10.92

目录

一个使用MediaCodec的例子，正好可以从例子看编码的过程，可以借鉴参考。

编码过程：

从Camera preview callback里拿数据 -> 数据格式转换 -> 编码输入 ->　处理 -> 编码输出

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主要步骤：

以下是例子使用MeidaCodec的主要步骤，我把它摘出来了，详细部分见后面源代码。

• mediaCodec = MediaCodec.createEncoderByType("video/avc");

编码类型是avc

• MediaFormat mediaFormat = MediaFormat.createVideoFormat("video/avc", width,height);

根据宽高创建MediaFormat,设置参数需要MediaFormat.

• mediaFormat.setInteger(MediaFormat.KEY_BIT_RATE, bitrate);
mediaFormat.setInteger(MediaFormat.KEY_FRAME_RATE, framerate);
mediaFormat.setInteger(MediaFormat.KEY_COLOR_FORMAT,
MediaCodecInfo.CodecCapabilities.COLOR_FormatYUV420Planar);
mediaFormat.setInteger(MediaFormat.KEY_I_FRAME_INTERVAL, 1);

根据当前需求设置参数

• mediaCodec.configure(mediaFormat, null, null,
MediaCodec.CONFIGURE_FLAG_ENCODE);

参数2表示编码后输出到哪个surface，这里编码直接输出到buffer，所以可以为NULL。
参数4设置MediaCodec.CONFIGURE_FLAG_ENCODE表示配置成编码器。

• mediaCodec.start();

开始运行

• avcCodec.offerEncoder(arg0,h264);

Camera preview callback拿到数据arg0后送到编码器，编码完成后输出到h264缓存里。
swapYV12toI420(input, yuv420, m_width, m_height);
由于camera输出的数据格式和编码器支持的输入数据格式不一致，需要先转换。

• mediaCodec.getInputBuffers(); inputBufferIndex =
mediaCodec.dequeueInputBuffer(-1); ByteBuffer inputBuffer =
inputBuffers[inputBufferIndex];

获取输入空闲buffer，然后得到空闲buffer中的一个index，这样就可以得到要使用的buffer了

• inputBuffer.put(yuv420);
mediaCodec.queueInputBuffer(inputBufferIndex, 0, input.length, 0,
0);

输入入队准备后就开始编码处理了

• ByteBuffer[] outputBuffers = mediaCodec.getOutputBuffers();
outputBufferIndex = mediaCodec.dequeueOutputBuffer(bufferInfo,0);
outputBuffer = outputBuffers[outputBufferIndex];

同样的方式，编码处理完成取出编码后的数据buffer

• mediaCodec.releaseOutputBuffer(outputBufferIndex, false);

当前buffer用好了就释放掉给下一轮编码使用

• FileOut.write(output,0,pos);

编码后的数据可以做拿去解码，网络发送等，这里就写到文件保存下来。

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例子源代码：

主代码部分：

package com.example.com.rk.dec_enc;import java.io.File;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.IOException;import android.graphics.ImageFormat;import android.hardware.Camera;import android.hardware.Camera.PreviewCallback;import android.media.AudioManager;import android.media.MediaPlayer;import android.os.Bundle;import android.annotation.SuppressLint;import android.app.Activity;import android.util.Log;import android.view.Menu;import android.view.SurfaceHolder;import android.view.SurfaceHolder.Callback;import android.view.SurfaceView;import android.view.View;@SuppressLint("NewApi") public class MainActivity extends Activity implements PreviewCallback {    AvcEncoder avcCodec = null;    AvcDecoder avcDecodec = null;    boolean avcDecFlag = false;    boolean avcEncFlag = false;    //boolean RecordCameraFrameDataFlag = true;    boolean RecordCameraFrameDataFlag = false;    public Camera m_camera;      SurfaceView   m_prevewview;    SurfaceHolder m_surfaceHolder;    SurfaceView   mDecSurfaceView;    SurfaceHolder mDecSurfaceHolder;    MediaPlayer mMediaPlayer;    private SurfaceHolder.Callback mSurfaceCallback;    int width = 1280;    int height = 720;    int framerate = 30;    int bitrate = 500000;    FileOutputStream FileOut = null;     byte[] h264 = new byte[width*height*3/2];    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        m_prevewview = (SurfaceView) findViewById(R.id.SurfaceViewPlay);        mDecSurfaceView = (SurfaceView) findViewById(R.id.SurfaceViewPlay_Dec);        mSurfaceCallback = new SurfaceHolder.Callback(){            @Override            public void surfaceChanged(SurfaceHolder arg0, int arg1, int arg2,                    int arg3) {                // TODO Auto-generated method stub            }            @Override            public void surfaceCreated(SurfaceHolder arg0) {                // TODO Auto-generated method stub                Log.d("Hery", "arg0  =" + arg0);                mDecSurfaceHolder = mDecSurfaceView.getHolder(); // Bind SurfaceView. get SurfaceHolder context                m_surfaceHolder = m_prevewview.getHolder(); // Bind SurfaceView get SurfaceHolder context                mDecSurfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);                m_surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);                boolean m_surfaceHolderisCreat = m_surfaceHolder.isCreating();                Log.d("Hery", "m_surfaceHolder  =" + m_surfaceHolderisCreat);                boolean mmDecSurfaceHolderisCreat = mDecSurfaceHolder.isCreating();                Log.d("Hery", "mmDecSurfaceHolderisCreat  =" + mmDecSurfaceHolderisCreat);                if(mmDecSurfaceHolderisCreat == true && (avcDecodec== null) && (avcDecFlag == false))                {                    Log.d("Hery", "Create AvcDecoder");                    avcDecodec = new AvcDecoder(width,height,mDecSurfaceHolder);                    avcDecFlag = true;                }                if(m_surfaceHolderisCreat == true && (avcCodec == null) && (avcEncFlag == false))                {                    Log.d("Hery", "Create Camera");                    avcCodec = new AvcEncoder(width,height,framerate,bitrate);                    avcEncFlag = true;                    m_camera = Camera.open();                    try {                        m_camera.setPreviewDisplay(m_surfaceHolder);                    } catch (IOException e) {                        // TODO Auto-generated catch block                        e.printStackTrace();                    }                    Camera.Parameters parameters = m_camera.getParameters();                    parameters.setPreviewSize(width, height);                    parameters.setPictureSize(width, height);                    parameters.setPreviewFormat(ImageFormat.YV12);                    m_camera.setParameters(parameters);                     m_camera.setPreviewCallback((PreviewCallback)MainActivity.this);                    m_camera.startPreview();                    }            }            @Override            public void surfaceDestroyed(SurfaceHolder arg0) {                // TODO Auto-generated method stub                Log.d("Hery","surfaceDestroyed");            }        };        mDecSurfaceView.getHolder().addCallback(mSurfaceCallback);        m_prevewview.getHolder().addCallback(mSurfaceCallback);        m_prevewview.setVisibility(View.VISIBLE);        mDecSurfaceView.setVisibility(View.VISIBLE);        if(RecordCameraFrameDataFlag)        {            try {                FileOut = new FileOutputStream(new File("/sdcard/app_camera.yuv"));            } catch (FileNotFoundException e) {                // TODO Auto-generated catch block                e.printStackTrace();            }        }    }    @Override    public boolean onCreateOptionsMenu(Menu menu) {        // Inflate the menu; this adds items to the action bar if it is present.        getMenuInflater().inflate(R.menu.main, menu);        return true;    }    @Override    public void onPreviewFrame(byte[] arg0, Camera arg1) {        //Log.d("Hery", "onPreviewFrame");        if(RecordCameraFrameDataFlag)        {            try {                FileOut.write(arg0,0,arg0.length);            } catch (IOException e) {                // TODO Auto-generated catch block                e.printStackTrace();            }        }        // TODO Auto-generated method stub        int size = avcCodec.offerEncoder(arg0,h264);        avcDecodec.pushData(h264,size);    }   }

编码部分：

package com.example.com.rk.dec_enc;import java.io.File;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.IOException;import java.nio.ByteBuffer;import android.annotation.SuppressLint;import android.media.MediaCodec;import android.media.MediaCodecInfo;import android.media.MediaFormat;import android.util.Log;@SuppressLint("NewApi") public class AvcEncoder {    private MediaCodec mediaCodec;    int m_width;    int m_height;    //boolean RecordEncDataFlag = true;    boolean RecordEncDataFlag = false;    byte[] m_info = null;    FileOutputStream FileOut = null;     private byte[] yuv420 = null;     public AvcEncoder(int width, int height, int framerate, int bitrate) {         Log.d("Hery", "AvcEncoder IN");        m_width  = width;        m_height = height;        yuv420 = new byte[width*height*3/2];        mediaCodec = MediaCodec.createEncoderByType("video/avc");        MediaFormat mediaFormat = MediaFormat.createVideoFormat("video/avc", width, height);        mediaFormat.setInteger(MediaFormat.KEY_BIT_RATE, bitrate);        mediaFormat.setInteger(MediaFormat.KEY_FRAME_RATE, framerate);        mediaFormat.setInteger(MediaFormat.KEY_COLOR_FORMAT, MediaCodecInfo.CodecCapabilities.COLOR_FormatYUV420Planar);            mediaFormat.setInteger(MediaFormat.KEY_I_FRAME_INTERVAL, 1);        mediaCodec.configure(mediaFormat, null, null, MediaCodec.CONFIGURE_FLAG_ENCODE);        mediaCodec.start();        if(RecordEncDataFlag)        {            try {                FileOut = new FileOutputStream(new File("/sdcard/app_camera_enc.h264"));            } catch (FileNotFoundException e) {                // TODO Auto-generated catch block                e.printStackTrace();            }        }    }    public void close() {        try {            mediaCodec.stop();            mediaCodec.release();        } catch (Exception e){             e.printStackTrace();        }        try {            FileOut.close();        } catch (IOException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }    }    public int offerEncoder(byte[] input, byte[] output)     {           //Log.d("......................................................Hery", "Encoder in");        int pos = 0;        swapYV12toI420(input, yuv420, m_width, m_height);        try {            ByteBuffer[] inputBuffers = mediaCodec.getInputBuffers();            ByteBuffer[] outputBuffers = mediaCodec.getOutputBuffers();            int inputBufferIndex = mediaCodec.dequeueInputBuffer(-1);            //Log.d("......................................................Hery", "inputBufferIndex = " +inputBufferIndex);            if (inputBufferIndex >= 0)             {                ByteBuffer inputBuffer = inputBuffers[inputBufferIndex];                inputBuffer.clear();                inputBuffer.put(yuv420);                mediaCodec.queueInputBuffer(inputBufferIndex, 0, input.length, 0, 0);            }            MediaCodec.BufferInfo bufferInfo = new MediaCodec.BufferInfo();            int outputBufferIndex = mediaCodec.dequeueOutputBuffer(bufferInfo,0);            //Log.d("......................................................Hery", "outputBufferIndex = " +outputBufferIndex);            while (outputBufferIndex >= 0)             {                ByteBuffer outputBuffer = outputBuffers[outputBufferIndex];                byte[] outData = new byte[bufferInfo.size];                outputBuffer.get(outData);                if(m_info != null)                {                                   System.arraycopy(outData, 0,  output, pos, outData.length);                    pos += outData.length;                }                else                {                     ByteBuffer spsPpsBuffer = ByteBuffer.wrap(outData);                       if (spsPpsBuffer.getInt() == 0x00000001)                      {                           m_info = new byte[outData.length];                         System.arraycopy(outData, 0, m_info, 0, outData.length);                         System.arraycopy(outData, 0, output, pos, outData.length);                         pos+=outData.length;                     }                      else                      {                              return -1;                     }                      }                mediaCodec.releaseOutputBuffer(outputBufferIndex, false);                outputBufferIndex = mediaCodec.dequeueOutputBuffer(bufferInfo, 0);            }            if(output[4] == 0x65) //key frame            {                System.arraycopy(output, 0,  yuv420, 0, pos);                System.arraycopy(m_info, 0,  output, 0, m_info.length);                System.arraycopy(yuv420, 0,  output, m_info.length, pos);                pos += m_info.length;            }        } catch (Throwable t) {            t.printStackTrace();        }        //Log.d("......................................................Hery", "Encoder out");        if(RecordEncDataFlag)        {            try {                FileOut.write(output,0,pos);            } catch (IOException e) {                // TODO Auto-generated catch block                e.printStackTrace();            }        }        return pos;    }    private void swapYV12toI420(byte[] yv12bytes, byte[] i420bytes, int width, int height)     {              System.arraycopy(yv12bytes, 0, i420bytes, 0,width*height);        System.arraycopy(yv12bytes, width*height+width*height/4, i420bytes, width*height,width*height/4);        System.arraycopy(yv12bytes, width*height, i420bytes, width*height+width*height/4,width*height/4);      } }

参考：

Android中直播视频技术探究之—基础知识大纲介绍