Audio quality difference on Kitkat / Lollipop

Question

I am attempting to record audio on Android and encounter issues with the quality, respectively the chosen format.

I use the following setup

mr=new MediaRecorder();
mr.setAudioSource(MediaRecorder.AudioSource.MIC);
mr.setOutputFormat(MediaRecorder.OutputFormat.MPEG_4);
mr.setOutputFile("somepath");
mr.setAudioEncoder(MediaRecorder.AudioEncoder.AAC);

That code however returns very different results on two devices running different Android versions (4.4.4 and 5.1.1).

When I take a look at the file headers, it shows different formats for both files there (3gp4 on 4.4.4 - mp42 on 5.1.1). VLC however "insists" on both using AAC, but shows very different sampling rates, 8k for the 4.4.4 file and 48k for 5.1.1.

Anybody an idea why?

Answer 1

Try to set all of this:

recorder.setAudioSource(MediaRecorder.AudioSource.MIC);
recorder.setOutputFormat(MediaRecorder.OutputFormat.MPEG_4);
recorder.setAudioEncoder(MediaRecorder.AudioEncoder.AAC); //I would use MediaRecorder.AudioEncoder.AMR_NB
recorder.setAudioEncodingBitRate(16);
recorder.setAudioSamplingRate(44100);
recorder.setOutputFile(outputFile.getAbsolutePath());
recorder.prepare();
recorder.start();

Or use external library: http://rehearsalassist.svn.sourceforge.net/viewvc/rehearsalassist/android/releases/RehearsalAssistant_0_8_2/src/urbanstew/RehearsalAssistant/

By changing recorder:

 RehearsalAudioRecorder recorder = new RehearsalAudioRecorder(RehearsalAudioRecorder.RECORDING_UNCOMPRESSED, MediaRecorder.AudioSource.MIC, 44100, AudioFormat.CHANNEL_CONFIGURATION_STEREO, AudioFormat.ENCODING_PCM_16BIT);
 recorder.setOutputFile(outputFile.getAbsolutePath());
 recorder.prepare();
 recorder.start();

UPDATE

Check also this:

MediaRecorder recorder = new MediaRecorder();
recorder.setAudioSource(MediaRecorder.AudioSource.MIC);
if (Build.VERSION.SDK_INT >= 10) {
    recorder.setAudioSamplingRate(44100);
    recorder.setAudioEncodingBitRate(96000);
    recorder.setOutputFormat(MediaRecorder.OutputFormat.MPEG_4);
    recorder.setAudioEncoder(MediaRecorder.AudioEncoder.AAC);
} else {
    // older version of Android, use crappy sounding voice codec
    recorder.setAudioSamplingRate(8000);
    recorder.setAudioEncodingBitRate(12200);
    recorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);
    recorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);
}
recorder.setOutputFile(file.getAbsolutePath());
try {
    recorder.prepare();
} catch (IOException e) {
    throw new RuntimeException(e);
}

It seems like devices with SDK lower than 10 cannot record good quality.