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/*
* Copyright (C) 2014 Andrew Comminos
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package se.lublin.humla.audio;
import android.media.AudioFormat;
import android.media.AudioRecord;
import android.media.audiofx.AcousticEchoCanceler;
import android.media.audiofx.AutomaticGainControl;
import android.media.audiofx.NoiseSuppressor;
import android.os.Build;
import android.util.Log;
import se.lublin.humla.Constants;
import se.lublin.humla.exception.AudioInitializationException;
import se.lublin.humla.exception.NativeAudioException;
import se.lublin.humla.protocol.AudioHandler;
/**
* Created by andrew on 23/08/13.
*/
public class AudioInput implements Runnable {
public static final int[] SAMPLE_RATES = { 48000, 44100, 16000, 8000 };
// AudioRecord state
private AudioInputListener mListener;
private AudioRecord mAudioRecord;
private final int mFrameSize;
private AcousticEchoCanceler mAEC = null;
private Thread mRecordThread;
private boolean mRecording;
public AudioInput(AudioInputListener listener, int audioSource, int targetSampleRate)
throws NativeAudioException, AudioInitializationException {
mListener = listener;
// Attempt to construct an AudioRecord with the target sample rate first.
// If it fails, keep producing AudioRecord instances until we find one that initializes
// correctly. Maybe one day Android will let us probe for supported sample rates, as we
// aren't even guaranteed that 44100hz will work across all devices.
for (int i = 0; i < SAMPLE_RATES.length + 1; i++) {
int sampleRate = i == 0 ? targetSampleRate : SAMPLE_RATES[i - 1];
try {
mAudioRecord = setupAudioRecord(sampleRate, audioSource);
break;
} catch (AudioInitializationException e) {
// Continue iteration, probing for a supported sample rate.
}
}
if (mAudioRecord == null) {
throw new AudioInitializationException("Unable to initialize AudioInput.");
}
setupAEC();
int sampleRate = getSampleRate();
// FIXME: does not work properly if 10ms frames cannot be represented as integers
mFrameSize = (sampleRate * AudioHandler.FRAME_SIZE) / AudioHandler.SAMPLE_RATE;
}
private static AudioRecord setupAudioRecord(int sampleRate, int audioSource) throws AudioInitializationException {
int minBufferSize = AudioRecord.getMinBufferSize(sampleRate, AudioFormat.CHANNEL_IN_MONO,
AudioFormat.ENCODING_PCM_16BIT);
if (minBufferSize <= 0)
throw new AudioInitializationException("Invalid buffer size returned (unsupported sample rate).");
AudioRecord audioRecord;
try {
audioRecord = new AudioRecord(audioSource, sampleRate, AudioFormat.CHANNEL_IN_MONO,
AudioFormat.ENCODING_PCM_16BIT, minBufferSize);
} catch (IllegalArgumentException e) {
throw new AudioInitializationException(e);
}
if(audioRecord.getState() == AudioRecord.STATE_UNINITIALIZED) {
audioRecord.release();
throw new AudioInitializationException("AudioRecord failed to initialize!");
}
return audioRecord;
}
private void setupAEC() {
if (mAudioRecord == null) {
return;
}
if (Build.VERSION.SDK_INT < Build.VERSION_CODES.JELLY_BEAN) {
return;
}
// TODO "On some devices, an AEC can be inserted by default in the
// capture path by the platform according to the
// MediaRecorder.AudioSource used. The application should call
// AcousticEchoCanceler.getEnable() after creating the AEC to
// check the default AEC activation state on a particular
// AudioRecord session."
// https://developer.android.com/reference/android/media/audiofx/AcousticEchoCanceler.html
// vv same for AGC and NS
// Read https://source.android.com/devices/audio/implement-pre-processing
int audioSessionId = mAudioRecord.getAudioSessionId();
if (AcousticEchoCanceler.isAvailable()) {
mAEC = AcousticEchoCanceler.create(audioSessionId);
// TODO is this even needed?
mAEC.setEnabled(true);
}
// TODO?
// if (aec != null) {
//  int ret = aec.setEnabled(enable);
//  if (ret != AudioEffect.SUCCESS) {
//  return false;
//  }
//  }
return;
// if(AutomaticGainControl.isAvailable()) {
// AutomaticGainControl.create(audioSessionId);
// }
// if(NoiseSuppressor.isAvailable()) {
// NoiseSuppressor.create(audioSessionId);
// }
}
/**
* Starts the recording thread.
* Not thread-safe.
*/
public void startRecording() {
mRecording = true;
mRecordThread = new Thread(this);
mRecordThread.start();
}
/**
* Stops the record loop after the current iteration, joining it.
* Not thread-safe.
*/
public void stopRecording() {
if(!mRecording) return;
mRecording = false;
try {
mRecordThread.interrupt();
mRecordThread.join();
mRecordThread = null;
} catch (InterruptedException e) {
e.printStackTrace();
}
}
/**
* Stops the record loop and waits on it to finish.
* Releases native audio resources.
* NOTE: It is not safe to call startRecording after.
*/
public void shutdown() {
stopRecording();
if(mAudioRecord != null) {
mAudioRecord.release();
mAudioRecord = null;
if (mAEC != null) {
mAEC.release();
mAEC = null;
}
}
}
public boolean isRecording() {
return mRecording;
}
/**
* @return the sample rate used by the AudioRecord instance.
*/
public int getSampleRate() {
return mAudioRecord.getSampleRate();
}
/**
* @return the frame size used, varying depending on the sample rate selected.
*/
public int getFrameSize() {
return mFrameSize;
}
@Override
public void run() {
android.os.Process.setThreadPriority(android.os.Process.THREAD_PRIORITY_URGENT_AUDIO);
Log.i(Constants.TAG, "AudioInput: started");
mAudioRecord.startRecording();
if(mAudioRecord.getState() != AudioRecord.STATE_INITIALIZED)
return;
final short[] mAudioBuffer = new short[mFrameSize];
// We loop when the 'recording' instance var is true instead of checking audio record state because we want to always cleanly shutdown.
while(mRecording) {
int shortsRead = mAudioRecord.read(mAudioBuffer, 0, mFrameSize);
if(shortsRead > 0) {
mListener.onAudioInputReceived(mAudioBuffer, mFrameSize);
} else {
Log.e(Constants.TAG, "Error fetching audio! AudioRecord error " + shortsRead);
}
}
mAudioRecord.stop();
Log.i(Constants.TAG, "AudioInput: stopped");
}
public interface AudioInputListener {
void onAudioInputReceived(short[] frame, int frameSize);
}
}
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