Live Audio Recording and Playing in Android and Thread & Callback Handling

Live Audio Recording and Playing in Android and Thread & callback handling

If your requirement is while it is recording it should play(means looping back audio), In your while loop thread, you are storing the recorded data (audioData bufer), there itself you can copy it to player object with in the while loop (player.write(audioData, 0, numShortsRead);). You said like your UI thread is stuck, it might be because of you are giving more priority to Audio record thread.

Check the below the code which I used for above loop back requirement

boolean m_isRun=true;
public void loopback() {
        // Prepare the AudioRecord & AudioTrack
        try {
            buffersize = AudioRecord.getMinBufferSize(SAMPLE_RATE,
                    AudioFormat.CHANNEL_CONFIGURATION_MONO,
                    AudioFormat.ENCODING_PCM_16BIT);

            if (buffersize <= BUF_SIZE) {
                buffersize = BUF_SIZE;
            }
            Log.i(LOG_TAG,"Initializing Audio Record and Audio Playing objects");

            m_record = new AudioRecord(MediaRecorder.AudioSource.MIC,
                    SAMPLE_RATE, AudioFormat.CHANNEL_CONFIGURATION_MONO,
                    AudioFormat.ENCODING_PCM_16BIT, buffersize * 1);

            m_track = new AudioTrack(AudioManager.STREAM_ALARM,
                    SAMPLE_RATE, AudioFormat.CHANNEL_CONFIGURATION_MONO,
                    AudioFormat.ENCODING_PCM_16BIT, buffersize * 1,
                    AudioTrack.MODE_STREAM);

            m_track.setPlaybackRate(SAMPLE_RATE);
        } catch (Throwable t) {
            Log.e("Error", "Initializing Audio Record and Play objects Failed "+t.getLocalizedMessage());
        }

        m_record.startRecording();
        Log.i(LOG_TAG,"Audio Recording started");
        m_track.play();
        Log.i(LOG_TAG,"Audio Playing started");

        while (m_isRun) {
            m_record.read(buffer, 0, BUF_SIZE);
            m_track.write(buffer, 0, buffer.length);
        }

        Log.i(LOG_TAG, "loopback exit");
    }

    private void do_loopback() {
        m_thread = new Thread(new Runnable() {
            public void run() {
                loopback();
            }
        });

One more thing, If your requirement is record for few seconds and then play, while it is playing your record should start again, you can do that with a delay handler thread with a time out, In that thread you can stop recording copy the buffer, then start recording.

thread problem when recording audio

You are calling findViewById() within record(), but record() is not running in the UI thread as you call it within the run() method of your new thread. As the error says:

android.view.ViewRoot$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views

Remove the call to findViewById() and text.setText() from your record() method. Instead, try setting your UI elements in onClickRecord() before you create the new thread.

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    text = (TextView)findViewById(R.id.TextView01);
}
...
public void onClickRecord(View v){
    text.setText("recording");
    thread = new Thread(new Runnable() {
        public void run() {
            isRecording = true;
            record();
        }
    });
    thread.start();
    isRecording = false;
}

Recording and saving audio based on click event android

Please check MediaRecorder api for android. You can record, save and use the file.

Audio Record and play loopback Issue

This issue is resolved, The problem is in device source, I tested it in many other devices. it is working fine.

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