本篇介绍
本篇介绍下AudioTrack和AudioRecord的使用，通过AudioRecord录音，通过AudioTrack播放录制的音频。
AudioRecord的使用
AudioRecord负责采集音频，下面是一个录音的例子：
代码语言：javascript复制 private void startRecord() {
int sampleRate = 44100;
int bufferSize = AudioRecord.getMinBufferSize(sampleRate, AudioFormat.CHANNEL_IN_MONO, AudioFormat.ENCODING_PCM_8BIT);
recorder = new AudioRecord(MediaRecorder.AudioSource.MIC, 44100, AudioFormat.CHANNEL_IN_MONO, AudioFormat.ENCODING_PCM_8BIT, bufferSize);
recorder.startRecording();
currentState = 0;
Log.d(TAG, "start record");
executorService.submit(new Runnable() {
@Override
public void run() {
byte byteBuffer [] = new byte[1024];
FileOutputStream outputStream = null;
try {
outputStream = new FileOutputStream(PCM_FILE);
} catch (FileNotFoundException e) {
e.printStackTrace();
return;
}
while (currentState != 1) {
int read = recorder.read(byteBuffer, 0, byteBuffer.length);
Log.d(TAG, "size is " read);
try {
outputStream.write(byteBuffer, 0, read);
} catch (IOException e) {
e.printStackTrace();
}
}
try {
outputStream.flush();
outputStream.close();
} catch (IOException e) {
e.printStackTrace();
}
recorder.stop();
}
});
}先创建一个AudioRecord，创建的时候需要指定音频源，采集频率，采集位数，声道数，还有buffer大小，AUdioRecord提供了专门的方法来计算buffer大小。创建好后，调用startRecording就可以采集了。具体采集需要在单独的线程里面做，调用AudioRecord的read就可以，读出来的内容就是采集的数据，这儿是写到了一个文件里面。
AudioTrack的使用
AudioTrack负责播放pcm数据，下面的代码是将刚采集的pcm播放出来
代码语言：javascript复制 AudioAttributes audioAttributes = new AudioAttributes.Builder().setContentType(AudioAttributes.CONTENT_TYPE_MUSIC).setUsage(AudioAttributes.USAGE_MEDIA).build();
AudioFormat audioFormat = new AudioFormat.Builder().setEncoding(AudioFormat.ENCODING_PCM_8BIT).setSampleRate(44100).setChannelMask(AudioFormat.CHANNEL_OUT_MONO).build();
int bufferSize = AudioTrack.getMinBufferSize(44100, AudioFormat.CHANNEL_OUT_MONO, AudioFormat.ENCODING_PCM_8BIT);
tracker = new AudioTrack(audioAttributes, audioFormat, bufferSize, AudioTrack.MODE_STREAM, AudioManager.AUDIO_SESSION_ID_GENERATE);
tracker.play();
currentState = 2;
executorService.submit(new Runnable() {
@Override
public void run() {
byte[] data = new byte[1024]; // small buffer size to not overflow AudioTrack's internal buffer
FileInputStream fileInputStream = null;
try {
fileInputStream = new FileInputStream(new File(PCM_FILE));
} catch (FileNotFoundException e) {
e.printStackTrace();
}
int readSize = 0;
while (readSize != -1) {
try {
readSize = fileInputStream.read(data);
} catch (IOException e) {
e.printStackTrace();
continue;
}
Log.d(TAG, "start play read size is " readSize);
if (readSize > 0) {
tracker.write(data, 0, readSize);
}
}
try {
fileInputStream.close();
}
catch (IOException e) {
// handle exception
}
tracker.stop();
tracker.release();
}
});首先是创建AudioTrack，也是需要指定采集位数，采集频率，输出声道，播放buffer，然后调用play就可以播放了，具体的播放就是在单独线程里面调用AudioTrack的write即可。
查看pcm数据
使用audacity就可以查看pcm数据，(下载路径 https://www.audacityteam.org/) 效果如下：
image.png
完整代码路径(https://github.com/leehaoran/opengl/tree/main/audioexample)
