Convert pcm

[TooLazyy]

Hi, im recording audio track in android with AudioRecord object instance. sample rate = 16 000, channel config = mono_in format = ENCODING_PCM_16BIT

I tried to convert recorded file into aac, m4a, flac. Every time conversion is failed. Is it actually possible to convert from poor pcm? P.S. recorded file extension *.pcm (tried *.ogg)

[tehscott]

In order to do this I first had to convert PCM to WAV, as follows (found somewhere on SO):

private int frequency = 44100;
private mBufferSize = AudioRecord.getMinBufferSize(frequency, AudioFormat.CHANNEL_IN_MONO, AudioFormat.ENCODING_PCM_16BIT);
private static final int RECORDER_BPP = 16;

private void copyWaveFile(String inFilename /*pcm file*/, String outFilename /*wav file*/) {
  FileInputStream in;
  FileOutputStream out;

  long totalAudioLen;
  long totalDataLen;
  long longSampleRate = frequency;
  int channels = 1;
  long byteRate = RECORDER_BPP * frequency * channels/8;

  byte[] data = new byte[mBufferSize];

  try {
    in = getActivity().openFileInput(inFilename);
    out = getActivity().openFileOutput(outFilename, Context.MODE_PRIVATE);
    totalAudioLen = in.getChannel().size();
    totalDataLen = totalAudioLen + 36;

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

    while(in.read(data) != -1){
      out.write(data);
    }

    in.close();
    out.close();
  } catch (FileNotFoundException e) {
    e.printStackTrace();
  } catch (IOException e) {
    e.printStackTrace();
  }
}

private void writeWaveFileHeader(
    FileOutputStream out, long totalAudioLen,
    long totalDataLen, long longSampleRate, int channels,
    long byteRate) throws IOException {

  byte[] header = new byte[44];

  header[0] = 'R';  // RIFF/WAVE header
  header[1] = 'I';
  header[2] = 'F';
  header[3] = 'F';
  header[4] = (byte) (totalDataLen & 0xff);
  header[5] = (byte) ((totalDataLen >> 8) & 0xff);
  header[6] = (byte) ((totalDataLen >> 16) & 0xff);
  header[7] = (byte) ((totalDataLen >> 24) & 0xff);
  header[8] = 'W';
  header[9] = 'A';
  header[10] = 'V';
  header[11] = 'E';
  header[12] = 'f';  // 'fmt ' chunk
  header[13] = 'm';
  header[14] = 't';
  header[15] = ' ';
  header[16] = 16;  // 4 bytes: size of 'fmt ' chunk
  header[17] = 0;
  header[18] = 0;
  header[19] = 0;
  header[20] = 1;  // format = 1
  header[21] = 0;
  header[22] = (byte) channels;
  header[23] = 0;
  header[24] = (byte) (longSampleRate & 0xff);
  header[25] = (byte) ((longSampleRate >> 8) & 0xff);
  header[26] = (byte) ((longSampleRate >> 16) & 0xff);
  header[27] = (byte) ((longSampleRate >> 24) & 0xff);
  header[28] = (byte) (byteRate & 0xff);
  header[29] = (byte) ((byteRate >> 8) & 0xff);
  header[30] = (byte) ((byteRate >> 16) & 0xff);
  header[31] = (byte) ((byteRate >> 24) & 0xff);
  header[32] = (byte) (channels * 16 / 8);  // block align
  header[33] = 0;
  header[34] = RECORDER_BPP;  // bits per sample
  header[35] = 0;
  header[36] = 'd';
  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);
}