Apps Record a call using AudioRecord and process audiou

[gosom]

I am trying to implement an application that records voice during a call ( my voice not the caller's ) and do some audio processing to that signal.

For doing this I use AudioRecord class as following:

private static final int RECORDER_SAMPLERATE = 8000;

private static final int RECORDER_CHANNELS = AudioFormat.CHANNEL_IN_MONO;

private static final int RECORDER_AUDIO_ENCODING = AudioFormat.ENCODING_PCM_16BIT;

private static final int AUDIO_SOURCE = AudioSource.VOICE_UPLINK;

int N = AudioRecord.getMinBufferSize(RECORDER_SAMPLERATE, RECORDER_CHANNELS, RECORDER_AUDIO_ENCODING);

recorder = new AudioRecord(AUDIO_SOURCE, RECORDER_SAMPLERATE, RECORDER_CHANNELS, RECORDER_AUDIO_ENCODING, N*10);

Then I use the recorder.read() method to read the recording to a buffer process them and write them to a file.

When I try to hear the file with audacity the sound seems corrupted. Moreover I can hear also the caller's voice.

I would like to note that my code works when the audio source is the MIC (not during a call).

Is it something about the sample rate or some settings of the audio Recorder?

Any other ideas how to implement this?

Giorgos