Question

I need to be able to create a WAV file using the mic in Android. Currently, I’m having a lot of trouble. So far, this is my situation. I’m using parts of the micDroid project code to record thus:

//read thread


int sampleRate = 44100;
int bufferSize = AudioRecord.getMinBufferSize(sampleRate,android.media.AudioFormat.CHANNEL_CONFIGURATION_MONO,android.media.AudioFormat.ENCODING_PCM_16BIT);
AudioRecord ar = new AudioRecord(AudioSource.MIC,sampleRate,android.media.AudioFormat.CHANNEL_CONFIGURATION_MONO,android.media.AudioFormat.ENCODING_PCM_16BIT,bufferSize);
short[] buffer = new short[bufferSize];

ar.startRecording();
while(isRunning){
    try{
        int numSamples = ar.read(buffer, 0, buffer.length);
        queue.put(new Sample(buffer, numSamples));
    } catch (InterruptedException e){
        e.printStackTrace();
    }
}


//write thread


int sampleRate = 44100;
WaveWriter writer = new WaveWriter("/sdcard","recOut.wav",sampleRate,android.media.AudioFormat.CHANNEL_CONFIGURATION_MONO,android.media.AudioFormat.ENCODING_PCM_16BIT);
try {
    writer.createWaveFile();
} catch (IOException e) {
    e.printStackTrace();
}
while(isRunning){
    try {
        Sample sample = queue.take();
        writer.write(sample.buffer, sample.bufferSize);
    } catch (IOException e) {
        //snip
    }
}

Which appears to work fine, however the end result recognizably contains whatever I said, but it is horribly distorted. Here’s a screen cap of audacity (WMP refuses to play the file).

Any help would be greatly appreciated, let me know if you need more code / info.

Update

Following markus’s suggestions, here is my updated code:

int sampleRate = 16000;

writer = new WaveWriter("/sdcard","recOut.wav",sampleRate,android.media.AudioFormat.CHANNEL_IN_MONO,android.media.AudioFormat.ENCODING_PCM_16BIT);

int bufferSize = AudioRecord.getMinBufferSize(sampleRate,android.media.AudioFormat.CHANNEL_IN_MONO,android.media.AudioFormat.ENCODING_PCM_16BIT);
AudioRecord ar = new AudioRecord(AudioSource.MIC,sampleRate,android.media.AudioFormat.CHANNEL_IN_MONO,android.media.AudioFormat.ENCODING_PCM_16BIT,bufferSize);

byte[] buffer = new byte[bufferSize]; //all references changed from short to byte type

…and another audacity screencap:

Answer 1

CHANNEL_CONFIGURATION_MONO is deprecated as far as i know, use CHANNEL_IN_MONO. consider looking at rehearsalassistant project, afaik they use AudioRecord class, too. samplerates should be chosen to fit the standard sample rates like explained in this wikipedia article.