Android 使用librtmp推流【音频采集模块】

1.音频采集模块的接口initAudioDevice在RtmpPublisher初始化init()时被调用。

initAudioDevice中会创建AudioRecord对象

mAudioRecord = new AudioRecord(MediaRecorder.AudioSource.MIC,
sampleRate, channelConfig,audioFormat, buffsize);

2.音频采集模块的接口start在RtmpPublisher中调用startGather()时被调用。

start函数中开启一个音频采集线程

音频采集线程每次都调用mAudioRecord.read(buffer,0, buffer.length)读取音频数据。

读取到音频数据后调用mCallback.audioData(audio)将采集到的音频数据转发给音频编码模块。

具体的音频采集代码如下：

public class AudioGatherer {

private static final String TAG = "AudioGatherer";

private Config mConfig;

private AudioRecord mAudioRecord;
private byte[] buffer;
private Thread workThread;
private boolean loop;
private Callback mCallback;

public static AudioGatherer newInstance(Config config) {
return new AudioGatherer(config);

}
private AudioGatherer(Config config){
this.mConfig =config;
}

public static class Params {
public final int sampleRate;
public final int channelCount;

public Params(int sampleRate, int channelCount) {
this.sampleRate = sampleRate;
this.channelCount = channelCount;
}
}

/**
* 初始化录音
*/
public Params initAudioDevice() {
int[] sampleRates = {44100, 22050, 16000, 11025};
for (int sampleRate :
sampleRates) {
//编码制式
int audioFormat = mConfig.audioFormat;
// stereo 立体声，
int channelConfig = mConfig.channelConfig;
int buffsize = 2 * AudioRecord.getMinBufferSize(sampleRate, channelConfig, audioFormat);
mAudioRecord = new AudioRecord(MediaRecorder.AudioSource.MIC, sampleRate, channelConfig,
audioFormat, buffsize);
if (mAudioRecord.getState() != AudioRecord.STATE_INITIALIZED) {
continue;
}
this.buffer = new byte[Math.min(4096, buffsize)];

return new Params(sampleRate,
channelConfig == AudioFormat.CHANNEL_CONFIGURATION_STEREO ? 2 : 1);
}

return null;
}

/**
* 开始录音
*/
public void start() {
workThread = new Thread() {
@Override
public void run() {
mAudioRecord.startRecording();
while (loop && !Thread.interrupted()) {
int size = mAudioRecord.read(buffer, 0, buffer.length);
if (size < 0) {
Log.i(TAG, "audio ignore ,no data to read");
break;
}
if (loop) {
byte[] audio = new byte[size];
System.arraycopy(buffer, 0, audio, 0, size);
if (mCallback != null) {
mCallback.audioData(audio);
}
}
}

}
};

loop = true;
workThread.start();
}

public void stop() {
loop = false;
workThread.interrupt();
Log.i(TAG, "run: 调用stop");
mAudioRecord.stop();
}

public void release() {
mAudioRecord.release();
}

public void setCallback(Callback callback) {
this.mCallback = callback;
}

public interface Callback {
void audioData(byte[] data);
}
}