android - 用于 mp3 流和 AudioTrack 播放的 JLayer 解码器

Question

在尝试了很多东西从服务器播放和 mp3 之后（由于延迟问题不使用 MediaPlayer），我得到了一段几乎可以工作的代码。

我使用异步任务从服务器获取流，然后将其提供给 jLayer 的解码器以将其转换为 PCM 数据。然后我将它提供给 AudioTrack 实例。

现在我听到很多口吃，但我非常积极，因为至少我听到了一些东西。

有人可以帮我解决口吃问题或指出如何解决口吃问题吗？

非常感激！

package com.example.mediadecoderexample;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.nio.ByteBuffer;

import javazoom.jl.decoder.Bitstream;
import javazoom.jl.decoder.BitstreamException;
import javazoom.jl.decoder.Decoder;
import javazoom.jl.decoder.DecoderException;
import javazoom.jl.decoder.Header;
import javazoom.jl.decoder.SampleBuffer;
import android.app.Activity;
import android.media.AudioFormat;
import android.media.AudioManager;
import android.media.AudioTrack;
import android.media.MediaCodec;
import android.media.MediaCodec.BufferInfo;
import android.media.MediaExtractor;
import android.media.MediaFormat;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;

public class MainActivity extends Activity {

    public final String LOG_TAG = "mediadecoderexample";
    MediaCodec codec;
    MediaExtractor extractor; 
    MediaFormat format;
    ByteBuffer[] codecInputBuffers;
    ByteBuffer[] codecOutputBuffers;
    Boolean sawInputEOS = false;
    Boolean sawOutputEOS = false;
    AudioTrack mAudioTrack;
    BufferInfo info;
    String url = "http://82.201.100.9:8000/RADIO538_WEB_MP3";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        extractor = new MediaExtractor();

        try {
            extractor.setDataSource(url);
        } catch (IOException e) {
        }

        format = extractor.getTrackFormat(0);
        String mime = format.getString(MediaFormat.KEY_MIME);
        int sampleRate = format.getInteger(MediaFormat.KEY_SAMPLE_RATE);

        Log.i(LOG_TAG, "===========================");
        Log.i(LOG_TAG, "url "+url);
        Log.i(LOG_TAG, "mime type : "+mime);
        Log.i(LOG_TAG, "sample rate : "+sampleRate);
        Log.i(LOG_TAG, "===========================");

        codec = MediaCodec.createDecoderByType(mime);
        codec.configure(format, null , null , 0);
        codec.start();

        codecInputBuffers = codec.getInputBuffers();
        codecOutputBuffers = codec.getOutputBuffers();

        extractor.selectTrack(0); 

        mAudioTrack = new AudioTrack(
                AudioManager.STREAM_MUSIC, 
                sampleRate, 
                AudioFormat.CHANNEL_OUT_STEREO, 
                AudioFormat.ENCODING_PCM_16BIT, 
                AudioTrack.getMinBufferSize (
                        sampleRate, 
                        AudioFormat.CHANNEL_OUT_STEREO, 
                        AudioFormat.ENCODING_PCM_16BIT
                        ), 
                AudioTrack.MODE_STREAM
                );
         mAudioTrack.play();
         new LongOperation().execute("");
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

     public short[] decode(byte[] mp3_data) throws IOException {

            SampleBuffer output = null;
            InputStream inputStream = new ByteArrayInputStream(mp3_data);
            short[] pcmOut = {};
            try {
                Bitstream bitstream = new Bitstream(inputStream);
                Decoder decoder = new Decoder();
                boolean done = false;
                int i = 0;
                while (! done) {
                    Header frameHeader = bitstream.readFrame();
                    if (frameHeader == null) {
                        done = true;
                    } else {
                        output = (SampleBuffer) decoder.decodeFrame(frameHeader, bitstream);
                        short[] next = output.getBuffer();
                        pcmOut = concatArrays(pcmOut, next);
                        mAudioTrack.write(pcmOut, 0, pcmOut.length);
                    }

                    bitstream.closeFrame();
                    i++;
                }
                return pcmOut;

            } catch (BitstreamException e) {
                throw new IOException("Bitstream error: " + e);
            } catch (DecoderException e) {
                Log.w(LOG_TAG, "Decoder error", e);
            }
            return null;
        }


        short[] concatArrays(short[] A, short[] B) {

            int aLen = A.length;
            int bLen = B.length;
            short[] C= new short[aLen+bLen];

            System.arraycopy(A, 0, C, 0, aLen);
            System.arraycopy(B, 0, C, aLen, bLen);

            return C;
        }

    private class LongOperation extends AsyncTask<String, Void, String> {
        @Override
        protected String doInBackground(String... params) {


            URL u;
            HttpURLConnection c;
            try {
                u = new URL(url);
                c = (HttpURLConnection) u.openConnection();

                c.setRequestMethod("GET");
                c.setDoOutput(false);
                c.connect();

                InputStream in = c.getInputStream();


                byte[] buffer = new byte[1024];
                int len1 = 0;
                while ( (len1 = in.read(buffer)) > 0 ) {
                    Log.i(LOG_TAG, buffer.length+" bytes input"); 
                    short[] pcmOut = MainActivity.this.decode(buffer);
                    Log.i(LOG_TAG, pcmOut.length+" bytes ouput"); 
                }
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            return null;
        }

        @Override
        protected void onPostExecute(String result) {
        }

        @Override
        protected void onPreExecute() {
        }

        @Override
        protected void onProgressUpdate(Void... values) {
        }
    }
}