【HarmonyOS】实现从视频提取音频并保存到pcm文件功能（API6 Java）

// 可创建VideoDecoder类，实现相关功能           
  private Format format;
  private Codec decoder;
  private Extractor extractor;

  public void createDecoder() {
      decoder = Codec.createDecoder(); // 创建解码器
      extractor = new Extractor(); // 创建Extractor解封装类
      boolean ret = extractor.setSource(new Source("/data/data/com.harmonyospro.myapplication/vedio_audio_test.mp4")); // 设置数据源，com.harmonyospro.myapplication为应用包名；也可设置为网络视频数据源
      System.out.println("setSource ret = " + ret);
      int trackCount = extractor.getTotalStreams();//获取轨道
      for (int i = 0; i < trackCount; i++) {
          format = extractor.getStreamFormat(i);
          if (format.getStringValue("mime").contains("audio")) { // 视频video，audio音频
              /**
               * @tc.steps: step2.set codec format for decoder
               * @tc.expected: step2.the return value is true
               */
              ret = decoder.setCodecFormat(format);
              System.out.println("setCodecFormat ret = " + ret);
              ret = extractor.specifyStream(i);
              System.out.println("specifyStream ret = " + ret);
              System.out.println("format.toString() = " + format.toString());
              System.out.println("format.getStringValue(mine) = "+format.getStringValue("mime"));
              System.out.println("format.getStringValue(width) = "+format.getIntValue("width"));
              System.out.println("format.getStringValue(height) = "+format.getIntValue("height"));
              break;
          }
      }
      decoder.registerCodecListener(listener);
  }

  Codec.ICodecListener listener = new Codec.ICodecListener() {
      @Override
      public void onReadBuffer(ByteBuffer byteBuffer, BufferInfo bufferInfo, int i) {
          Format fmt = decoder.getBufferFormat(byteBuffer);
          System.out.println("fmt.toString() = " + fmt.toString());
          // 写入文件
          writeFile(byteBuffer,bufferInfo,i);
          System.out.println("onReadBuffer == " + bufferInfo.toString());
      }

      @Override
      public void onError(int errorCode, int act, int trackId) {
          throw new RuntimeException();
      }
  };

  /**
   * 调用 start()方法开始解码
   */
  public void start(){
      boolean start = decoder.start();
      System.out.println("start = " + start);
  }

  /**
   * 调用getAvailableBuffer取到一个可用的ByteBuffer，把数据填入ByteBuffer里，然后再调用writeBuffer把ByteBuffer写入解码器实例
   */
  public void framebuffer(){
      int i = 1;
      boolean reachEnd = false;
      while (!reachEnd){
          extractor.next();//下一帧
          ByteBuffer dstBuf = null;
          dstBuf = decoder.getAvailableBuffer(100000);

          if (dstBuf == null) {
              try {
                  Thread.sleep(200);
              } catch (InterruptedException e) {
                  System.out.println("InterruptedException");
              }
              continue;
          }
          System.out.println("02b dstBuf.toString() = " + dstBuf.toString());
          BufferInfo bufferInfo = new BufferInfo();
          bufferInfo.offset = 0;
          bufferInfo.size = extractor.readBuffer(dstBuf, 0);
          bufferInfo.timeStamp = extractor.getFrameTimestamp();
          bufferInfo.bufferType = extractor.getFrameType();
          System.out.println("bufferInfo bufferInfo = " + bufferInfo.timeStamp);
          reachEnd =  extractor.getStreamId() == -1;
          System.out.println("reachEnd = " + reachEnd);
          if(reachEnd){
              bufferInfo.bufferType = bufferInfo.BUFFER_TYPE_END_OF_STREAM;
          }
          boolean ret = decoder.writeBuffer(dstBuf, bufferInfo);
          System.out.println("writeBuffer ret = " + ret);

          try {
              Thread.sleep(200);
          } catch (InterruptedException e) {
              System.out.println("InterruptedException");
          }
      }
  } 

  /**
   * 停止解码，释放资源
   */
  public void stopAndRelease(){
      System.out.println("VedioDecoder stopAndRelease");
      decoder.stop();
      decoder.release();
  } 

private void writeFile(ByteBuffer outputBuffer, BufferInfo info, int trackId) {
    FileOutputStream fileOutputStream = null;
    File fd = new File("/data/data/com.harmonyospro.myapplication/1.pcm");
    try {
        fileOutputStream = new FileOutputStream(fd, true);
        final byte[] chunk = new byte[info.size];
        outputBuffer.get(chunk);
        fileOutputStream.write(chunk, 0, outputBuffer.limit());
        outputBuffer.clear();
    } catch (FileNotFoundException e) {
        System.out.println("02b FileNotFoundException");
    } catch (IOException e) {
        System.out.println("02b IOException");
    }finally {
        try {
            fileOutputStream.close();
        } catch (IOException e) {
            System.out.println("IOException");
        }
    }
}

VideoDecoder videoDecoder = new VideoDecoder();
videoDecoder.createDecoder();
videoDecoder.start();
videoDecoder.framebuffer();
//vedioDecoder.stopAndRelease(); // 需要停止的时候停止