Android音频编辑之音频转换PCM与WAV

//采样率 * 通道数 * 采样位数/8 * 秒数
8000 * 1 * 8/8 * 60 = 480000，大约480k

//采样率 * 通道数 * 采样位数/8 * 秒数
44100 * 2 * 16/8 * 60 = 10584000，大约10M

 /**
 * 将音乐文件解码
 *
 * @param musicFileUrl 源文件路径
 * @param decodeFileUrl 解码文件路径
 * @param startMicroseconds 开始时间 微秒
 * @param endMicroseconds 结束时间 微秒
 * @param decodeOperateInterface 解码过程回调
 */
 private boolean decodeMusicFile(String musicFileUrl, String decodeFileUrl,
  long startMicroseconds, long endMicroseconds, DecodeOperateInterface decodeOperateInterface) {

 //采样率，声道数，时长，音频文件类型
 int sampleRate = 0;
 int channelCount = 0;
 long duration = 0;
 String mime = null;

 //MediaExtractor, MediaFormat, MediaCodec
 MediaExtractor mediaExtractor = new MediaExtractor();
 MediaFormat mediaFormat = null;
 MediaCodec mediaCodec = null;

 //给媒体信息提取器设置源音频文件路径
 try {
  mediaExtractor.setDataSource(musicFileUrl);
 }catch (Exception ex){
  ex.printStackTrace();
  try {
  mediaExtractor.setDataSource(new FileInputStream(musicFileUrl).getFD());
  } catch (Exception e) {
  e.printStackTrace();
  LogUtil.e("设置解码音频文件路径错误");
  }
 }

 //获取音频格式轨信息
 mediaFormat = mediaExtractor.getTrackFormat(0);

 //从音频格式轨信息中读取 采样率，声道数，时长，音频文件类型
 sampleRate = mediaFormat.containsKey(MediaFormat.KEY_SAMPLE_RATE) ? mediaFormat.getInteger(
  MediaFormat.KEY_SAMPLE_RATE) : 44100;
 channelCount = mediaFormat.containsKey(MediaFormat.KEY_CHANNEL_COUNT) ? mediaFormat.getInteger(
  MediaFormat.KEY_CHANNEL_COUNT) : 1;
 duration = mediaFormat.containsKey(MediaFormat.KEY_DURATION) ? mediaFormat.getLong(
  MediaFormat.KEY_DURATION) : 0;
 mime = mediaFormat.containsKey(MediaFormat.KEY_MIME) ? mediaFormat.getString(MediaFormat.KEY_MIME)
   : "";

 LogUtil.i("歌曲信息Track info: mime:"
  + mime
  + " 采样率sampleRate:"
  + sampleRate
  + " channels:"
  + channelCount
  + " duration:"
  + duration);

 if (TextUtils.isEmpty(mime) || !mime.startsWith("audio/")) {
  LogUtil.e("解码文件不是音频文件mime:" + mime);
  return false;
 }

 if (mime.equals("audio/ffmpeg")) {
  mime = "audio/mpeg";
  mediaFormat.setString(MediaFormat.KEY_MIME, mime);
 }

 if (duration <= 0) {
  LogUtil.e("音频文件duration为" + duration);
  return false;
 }

 //解码的开始时间和结束时间
 startMicroseconds = Math.max(startMicroseconds, 0);
 endMicroseconds = endMicroseconds < 0 ? duration : endMicroseconds;
 endMicroseconds = Math.min(endMicroseconds, duration);

 if (startMicroseconds >= endMicroseconds) {
  return false;
 }

 //创建一个解码器
 try {
  mediaCodec = MediaCodec.createDecoderByType(mime);

  mediaCodec.configure(mediaFormat, null, null, 0);
 } catch (Exception e) {
  LogUtil.e("解码器configure出错");
  return false;
 }

 //得到输出PCM文件的路径
 decodeFileUrl = decodeFileUrl.substring(0, decodeFileUrl.lastIndexOf("."));
 String pcmFilePath = decodeFileUrl + ".pcm";

 //后续解码操作
 getDecodeData(mediaExtractor, mediaCodec, pcmFilePath, sampleRate, channelCount,
  startMicroseconds, endMicroseconds, decodeOperateInterface);

 return true;
 }

 /**
 * 解码数据
 */
 private void getDecodeData(MediaExtractor mediaExtractor, MediaCodec mediaCodec,
  String decodeFileUrl, int sampleRate, int channelCount, final long startMicroseconds,
  final long endMicroseconds, final DecodeOperateInterface decodeOperateInterface) {

 //初始化解码状态，未解析完成
 boolean decodeInputEnd = false;
 boolean decodeOutputEnd = false;

 //当前读取采样数据的大小
 int sampleDataSize;
 //当前输入数据的ByteBuffer序号，当前输出数据的ByteBuffer序号
 int inputBufferIndex;
 int outputBufferIndex;
 //音频文件的采样位数字节数，= 采样位数/8
 int byteNumber;

 //上一次的解码操作时间，当前解码操作时间，用于通知回调接口
 long decodeNoticeTime = System.currentTimeMillis();
 long decodeTime;

 //当前采样的音频时间，比如在当前音频的第40秒的时候
 long presentationTimeUs = 0;

 //定义编解码的超时时间
 final long timeOutUs = 100;

 //存储输入数据的ByteBuffer数组，输出数据的ByteBuffer数组
 ByteBuffer[] inputBuffers;
 ByteBuffer[] outputBuffers;

 //当前编解码器操作的 输入数据ByteBuffer 和 输出数据ByteBuffer，可以从targetBuffer中获取解码后的PCM数据
 ByteBuffer sourceBuffer;
 ByteBuffer targetBuffer;

 //获取输出音频的媒体格式信息
 MediaFormat outputFormat = mediaCodec.getOutputFormat();

 MediaCodec.BufferInfo bufferInfo;

 byteNumber = (outputFormat.containsKey("bit-width") ? outputFormat.getInteger("bit-width") : 0) / 8;

 //开始解码操作
 mediaCodec.start();

 //获取存储输入数据的ByteBuffer数组，输出数据的ByteBuffer数组
 inputBuffers = mediaCodec.getInputBuffers();
 outputBuffers = mediaCodec.getOutputBuffers();

 mediaExtractor.selectTrack(0);

 //当前解码的缓存信息，里面的有效数据在offset和offset+size之间
 bufferInfo = new MediaCodec.BufferInfo();

 //获取解码后文件的输出流
 BufferedOutputStream bufferedOutputStream =
  FileFunction.getBufferedOutputStreamFromFile(decodeFileUrl);

 //开始进入循环解码操作，判断读入源音频数据是否完成，输出解码音频数据是否完成
 while (!decodeOutputEnd) {
  if (decodeInputEnd) {
  return;
  }

  decodeTime = System.currentTimeMillis();

  //间隔1秒通知解码进度
  if (decodeTime - decodeNoticeTime > Constant.OneSecond) {
  final int decodeProgress =
   (int) ((presentationTimeUs - startMicroseconds) * Constant.NormalMaxProgress
    / endMicroseconds);

  if (decodeProgress > 0) {
   notifyProgress(decodeOperateInterface, decodeProgress);
  }

  decodeNoticeTime = decodeTime;
  }

  try {

  //操作解码输入数据

  //从队列中获取当前解码器处理输入数据的ByteBuffer序号
  inputBufferIndex = mediaCodec.dequeueInputBuffer(timeOutUs);

  if (inputBufferIndex >= 0) {
   //取得当前解码器处理输入数据的ByteBuffer
   sourceBuffer = inputBuffers[inputBufferIndex];
   //获取当前ByteBuffer，编解码器读取了多少采样数据
   sampleDataSize = mediaExtractor.readSampleData(sourceBuffer, 0);

   //如果当前读取的采样数据<0，说明已经完成了读取操作
   if (sampleDataSize < 0) {
   decodeInputEnd = true;
   sampleDataSize = 0;
   } else {
   presentationTimeUs = mediaExtractor.getSampleTime();
   }

   //然后将当前ByteBuffer重新加入到队列中交给编解码器做下一步读取操作
   mediaCodec.queueInputBuffer(inputBufferIndex, 0, sampleDataSize, presentationTimeUs,
    decodeInputEnd ? MediaCodec.BUFFER_FLAG_END_OF_STREAM : 0);

   //前进到下一段采样数据
   if (!decodeInputEnd) {
   mediaExtractor.advance();
   }

  } else {
   //LogUtil.e("inputBufferIndex" + inputBufferIndex);
  }

  //操作解码输出数据

  //从队列中获取当前解码器处理输出数据的ByteBuffer序号
  outputBufferIndex = mediaCodec.dequeueOutputBuffer(bufferInfo, timeOutUs);

  if (outputBufferIndex < 0) {
   //输出ByteBuffer序号<0，可能是输出缓存变化了，输出格式信息变化了
   switch (outputBufferIndex) {
   case MediaCodec.INFO_OUTPUT_BUFFERS_CHANGED:
    outputBuffers = mediaCodec.getOutputBuffers();
    LogUtil.e(
     "MediaCodec.INFO_OUTPUT_BUFFERS_CHANGED [AudioDecoder]output buffers have changed.");
    break;
   case MediaCodec.INFO_OUTPUT_FORMAT_CHANGED:
    outputFormat = mediaCodec.getOutputFormat();

    sampleRate =
     outputFormat.containsKey(MediaFormat.KEY_SAMPLE_RATE) ? outputFormat.getInteger(
      MediaFormat.KEY_SAMPLE_RATE) : sampleRate;
    channelCount =
     outputFormat.containsKey(MediaFormat.KEY_CHANNEL_COUNT) ? outputFormat.getInteger(
      MediaFormat.KEY_CHANNEL_COUNT) : channelCount;
    byteNumber =
     (outputFormat.containsKey("bit-width") ? outputFormat.getInteger("bit-width") : 0)
      / 8;

    LogUtil.e(
     "MediaCodec.INFO_OUTPUT_FORMAT_CHANGED [AudioDecoder]output format has changed to "
      + mediaCodec.getOutputFormat());
    break;
   default:
    //LogUtil.e("error [AudioDecoder] dequeueOutputBuffer returned " + outputBufferIndex);
    break;
   }
   continue;
  }

  //取得当前解码器处理输出数据的ByteBuffer
  targetBuffer = outputBuffers[outputBufferIndex];

  byte[] sourceByteArray = new byte[bufferInfo.size];

  //将解码后的targetBuffer中的数据复制到sourceByteArray中
  targetBuffer.get(sourceByteArray);
  targetBuffer.clear();

  //释放当前的输出缓存
  mediaCodec.releaseOutputBuffer(outputBufferIndex, false);

  //判断当前是否解码数据全部结束了
  if ((bufferInfo.flags & MediaCodec.BUFFER_FLAG_END_OF_STREAM) != 0) {
   decodeOutputEnd = true;
  }

  //sourceByteArray就是最终解码后的采样数据
  //接下来可以对这些数据进行采样位数，声道的转换，但这是可选的，默认是和源音频一样的声道和采样位数
  if (sourceByteArray.length > 0 && bufferedOutputStream != null) {
   if (presentationTimeUs < startMicroseconds) {
   continue;
   }

   //采样位数转换，按自己需要是否实现
   byte[] convertByteNumberByteArray =
    convertByteNumber(byteNumber, Constant.ExportByteNumber, sourceByteArray);

   //声道转换，按自己需要是否实现
   byte[] resultByteArray = convertChannelNumber(channelCount, Constant.ExportChannelNumber,
    Constant.ExportByteNumber, convertByteNumberByteArray);

   //将解码后的PCM数据写入到PCM文件
   try {
   bufferedOutputStream.write(resultByteArray);
   } catch (Exception e) {
   LogUtil.e("输出解压音频数据异常" + e);
   }
  }

  if (presentationTimeUs > endMicroseconds) {
   break;
  }
  } catch (Exception e) {
  LogUtil.e("getDecodeData异常" + e);
  }
 }

 if (bufferedOutputStream != null) {
  try {
  bufferedOutputStream.close();
  } catch (IOException e) {
  LogUtil.e("关闭bufferedOutputStream异常" + e);
  }
 }

 //重置采样率，按自己需要是否实现
 if (sampleRate != Constant.ExportSampleRate) {
  Resample(sampleRate, decodeFileUrl);
 }

 notifyProgress(decodeOperateInterface, 100);

 //释放mediaCodec 和 mediaExtractor
 if (mediaCodec != null) {
  mediaCodec.stop();
  mediaCodec.release();
 }

 if (mediaExtractor != null) {
  mediaExtractor.release();
 }
 }

 /**
 * PCM文件转WAV文件
 * @param inPcmFilePath 输入PCM文件路径
 * @param outWavFilePath 输出WAV文件路径
 * @param sampleRate 采样率，例如44100
 * @param channels 声道数 单声道：1或双声道：2
 * @param bitNum 采样位数，8或16
 */
 public static void convertPcm2Wav(String inPcmFilePath, String outWavFilePath, int sampleRate,
  int channels, int bitNum) {

 FileInputStream in = null;
 FileOutputStream out = null;
 byte[] data = new byte[1024];

 try {
  //采样字节byte率
  long byteRate = sampleRate * channels * bitNum / 8;

  in = new FileInputStream(inPcmFilePath);
  out = new FileOutputStream(outWavFilePath);

  //PCM文件大小
  long totalAudioLen = in.getChannel().size();

  //总大小，由于不包括RIFF和WAV，所以是44 - 8 = 36，在加上PCM文件大小
  long totalDataLen = totalAudioLen + 36;

  writeWaveFileHeader(out, totalAudioLen, totalDataLen, sampleRate, channels, byteRate);

  int length = 0;
  while ((length = in.read(data)) > 0) {
  out.write(data, 0, length);
  }
 } catch (Exception e) {
  e.printStackTrace();
 } finally {
  if (in != null) {
  try {
   in.close();
  } catch (IOException e) {
   e.printStackTrace();
  }
  }
  if (out != null) {
  try {
   out.close();
  } catch (IOException e) {
   e.printStackTrace();
  }
  }
 }
 }


 /**
 * 输出WAV文件
 * @param out WAV输出文件流
 * @param totalAudioLen 整个音频PCM数据大小
 * @param totalDataLen 整个数据大小
 * @param sampleRate 采样率
 * @param channels 声道数
 * @param byteRate 采样字节byte率
 * @throws IOException
 */
 private static void writeWaveFileHeader(FileOutputStream out, long totalAudioLen,
  long totalDataLen, int sampleRate, int channels, long byteRate) throws IOException {
 byte[] header = new byte[44];
 header[0] = 'R'; // RIFF
 header[1] = 'I';
 header[2] = 'F';
 header[3] = 'F';
 header[4] = (byte) (totalDataLen & 0xff);//数据大小
 header[5] = (byte) ((totalDataLen >> 8) & 0xff);
 header[6] = (byte) ((totalDataLen >> 16) & 0xff);
 header[7] = (byte) ((totalDataLen >> 24) & 0xff);
 header[8] = 'W';//WAVE
 header[9] = 'A';
 header[10] = 'V';
 header[11] = 'E';
 //FMT Chunk
 header[12] = 'f'; // 'fmt '
 header[13] = 'm';
 header[14] = 't';
 header[15] = ' ';//过渡字节
 //数据大小
 header[16] = 16; // 4 bytes: size of 'fmt ' chunk
 header[17] = 0;
 header[18] = 0;
 header[19] = 0;
 //编码方式 10H为PCM编码格式
 header[20] = 1; // format = 1
 header[21] = 0;
 //通道数
 header[22] = (byte) channels;
 header[23] = 0;
 //采样率，每个通道的播放速度
 header[24] = (byte) (sampleRate & 0xff);
 header[25] = (byte) ((sampleRate >> 8) & 0xff);
 header[26] = (byte) ((sampleRate >> 16) & 0xff);
 header[27] = (byte) ((sampleRate >> 24) & 0xff);
 //音频数据传送速率,采样率*通道数*采样深度/8
 header[28] = (byte) (byteRate & 0xff);
 header[29] = (byte) ((byteRate >> 8) & 0xff);
 header[30] = (byte) ((byteRate >> 16) & 0xff);
 header[31] = (byte) ((byteRate >> 24) & 0xff);
 // 确定系统一次要处理多少个这样字节的数据，确定缓冲区，通道数*采样位数
 header[32] = (byte) (channels * 16 / 8);
 header[33] = 0;
 //每个样本的数据位数
 header[34] = 16;
 header[35] = 0;
 //Data chunk
 header[36] = 'd';//data
 header[37] = 'a';
 header[38] = 't';
 header[39] = 'a';
 header[40] = (byte) (totalAudioLen & 0xff);
 header[41] = (byte) ((totalAudioLen >> 8) & 0xff);
 header[42] = (byte) ((totalAudioLen >> 16) & 0xff);
 header[43] = (byte) ((totalAudioLen >> 24) & 0xff);
 out.write(header, 0, 44);
 }