Android MediaCodec 使用例子

Android MediaCodec 使用例子

下面的例子是使用MediaCodec 录制到文件的例子。

 1 public class AvcEncoder {  

 private MediaCodec mediaCodec;
 private BufferedOutputStream outputStream;  

 public AvcEncoder() {
     File f = new File(Environment.getExternalStorageDirectory(), "Download/video_encoded.264");
     touch (f);
     try {
         outputStream = new BufferedOutputStream(new FileOutputStream(f));
         Log.i("AvcEncoder", "outputStream initialized");
     } catch (Exception e){
         e.printStackTrace();
     }  

     mediaCodec = MediaCodec.createEncoderByType("video/avc");
     MediaFormat mediaFormat = MediaFormat.createVideoFormat("video/avc", 320, 240);
     mediaFormat.setInteger(MediaFormat.KEY_BIT_RATE, 125000);
     mediaFormat.setInteger(MediaFormat.KEY_FRAME_RATE, 15);
     mediaFormat.setInteger(MediaFormat.KEY_COLOR_FORMAT, MediaCodecInfo.CodecCapabilities.COLOR_FormatYUV420Planar);
     mediaFormat.setInteger(MediaFormat.KEY_I_FRAME_INTERVAL, 5);
     mediaCodec.configure(mediaFormat, null, null, MediaCodec.CONFIGURE_FLAG_ENCODE);
     mediaCodec.start();
 }  

 public void close() {
     try {
         mediaCodec.stop();
         mediaCodec.release();
         outputStream.flush();
         outputStream.close();
     } catch (Exception e){
         e.printStackTrace();
     }
 }  

 // called from Camera.setPreviewCallbackWithBuffer(...) in other class
 public void offerEncoder(byte[] input) {
     try {
         ByteBuffer[] inputBuffers = mediaCodec.getInputBuffers();
         ByteBuffer[] outputBuffers = mediaCodec.getOutputBuffers();
         int inputBufferIndex = mediaCodec.dequeueInputBuffer(-1);
         if (inputBufferIndex >= 0) {
             ByteBuffer inputBuffer = inputBuffers[inputBufferIndex];
             inputBuffer.clear();
             inputBuffer.put(input);
             mediaCodec.queueInputBuffer(inputBufferIndex, 0, input.length, 0, 0);
         }  

         MediaCodec.BufferInfo bufferInfo = new MediaCodec.BufferInfo();
         int outputBufferIndex = mediaCodec.dequeueOutputBuffer(bufferInfo,0);
         while (outputBufferIndex >= 0) {
             ByteBuffer outputBuffer = outputBuffers[outputBufferIndex];
             byte[] outData = new byte[bufferInfo.size];
             outputBuffer.get(outData);
             outputStream.write(outData, 0, outData.length);
             Log.i("AvcEncoder", outData.length + " bytes written");  

             mediaCodec.releaseOutputBuffer(outputBufferIndex, false);
             outputBufferIndex = mediaCodec.dequeueOutputBuffer(bufferInfo, 0);  

         }
     } catch (Throwable t) {
         t.printStackTrace();
     }  

 }  

这个例子配置了编码格式、视频大小、比特率、帧率等参数，然后在camera 预览的回调函数里把yuv420数据推送给mediacodec，编码后取出nalu，写入到文件。