wav - Change Bitrate of AudioRecord on Android -

how can on android bits per sample changed 16 bit 8 bit (or other bitrates) in audiorecord object when recording in wav format?

this doesn't work (as discussed example here: using audiorecord 8-bit encoding in android):

private static int recorder_audio_encoding =           audioformat.encoding_pcm_8bit; -->error: invalid audio format. buffersize = audiorecord.getminbuffersize(recorder_samplerate,recorder_channels,          recorder_audio_encoding); recorder = new audiorecord(mediarecorder.audiosource.mic,recorder_samplerate,           recorder_channels,recorder_audio_encoding, buffersize); 

with header:

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 content...         header[32] = (byte) (2 * 16 / 8);  // block align         header[33] = 0;         header[34] = (byte)recorder_bpp;  // bits per sample, set 8         ...header content...          out.write(header, 0, 44);     } 

you need record 16 bit samples using audioformat.encoding_pcm_16bit because 8 bit encoding not working on android devices.

then convert 16 bit buffer 8 bit on fly prior writing wave sound file. because 8 bit wave files use unsigned integers (0-255) silence being 128 instead of 0, suggested conversion corrects that. following code skeleton:

// source above defined value buffersize , recorder object samplebuffershorts = new short[buffersize]; samplebufferbytes = new short[buffersize]; int numberofshortsread = recorder.read(samlebuffershorts, 0, buffersize); if (numberofshortsread != error_invalid_operation && numberofshortsread != error_bad_value) {     (int = 0 ; < numberofshortsread ; ++i)         samplebufferbytes[i] = (byte)((samplebuffershorts[i]>>8)+128); } 

see https://stackoverflow.com/a/18777515/1986583 useful explanation why additional dithering improve resulting quality.