使用Jlayer和AudioTrack实现在线流媒体边下边播功能

jlayer：mp3解码库

http://www.javazoom.net/javalayer/javalayer.html

思路：通过http得到在线音频文件的输入流，将未解码的音频流使用jlayer进行解码操作，保存解码后的音频数据到队列中，通过另一线程读取解码后的音频数据，从而边下边播的功能

/**
* 解码操作
*/
private class DecodeThread extends Thread {

private InputStream inputStream = null;
private URL url = null;
private int sampleRate;
private int channel;

public DecodeThread(URL url, int sampleRate, int channel) {
this.url = url;
this.sampleRate = sampleRate;
this.channel = channel;
}

@Override
public void run() {
try {
ByteArrayOutputStream outStream = new ByteArrayOutputStream(8 * 1024);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
inputStream = new BufferedInputStream(conn.getInputStream(), 8 * 1024);
Bitstream bitstream = new Bitstream(inputStream);
Decoder decoder = new Decoder();
boolean done = false;
SampleBuffer output;
int frameIndex = 0;
while (!done) {
Header frameHeader = bitstream.readFrame();
if (frameHeader == null) {
done = true;
} else {
output = (SampleBuffer) decoder.decodeFrame(frameHeader, bitstream);
short[] pcm = output.getBuffer();
byte[] frameData = new byte[pcm.length];
for (int i = 0; i < pcm.length / 2; i++) {
int j = i * 2;
frameData[j] = (byte) (pcm[i] & 0xff);
frameData[j + 1] = (byte) ((pcm[i] >> 8) & 0xff);
}
audioFrame.add(frameData);
frameIndex++;
}
bitstream.closeFrame();
}
//TODO 缓存音频数据
outStream.close();
} catch (IOException e) {
e.printStackTrace();
} catch (BitstreamException e) {
e.printStackTrace();
} catch (DecoderException e) {
e.printStackTrace();
}
}
}

/**
* 播放
*/
private class PlayThread extends Thread {
@Override
public void run() {
mAudioTrack.play();
int tempFrameIndex = 0;

while (!isEnd) {
if (!isPausing) {
handler.sendEmptyMessage(SimplePlayerHelper.STATE_PLAY);
try {
Thread.sleep(50);
} catch (InterruptedException e) {
e.printStackTrace();
}

List<byte[]> tempFrame = new ArrayList<byte[]>();
synchronized (audioFrame) {
tempFrame.addAll(audioFrame.subList(tempFrameIndex, tempFrameIndex > audioFrame.size() - 40 ? audioFrame.size() : tempFrameIndex + 40));
}

if (tempFrameIndex > 0 && tempFrame.isEmpty()) {
handler.sendEmptyMessage(SimplePlayerHelper.STATE_END);
isEnd = true;
onCompletionListener.onCompletion(mMyAudioTrack);
}
for (int i = 0; i < tempFrame.size(); i++) {
mAudioTrack.write(tempFrame.get(i), 0, tempFrame.get(i).length);
}
tempFrameIndex += tempFrame.size();
}
}
audioFrame.clear();
mAudioTrack.stop();
}
}

仅支持MP3流的在线播放功能，可使用其他音频解码库实现多种音频编码格式的在线播放功能