【Android 多媒体应用】使用MediaCodec解码使用AudioTrack播放音频数据

1.MainActivity.java

import android.app.Activity;import android.os.Bundle;import android.os.Environment;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import java.io.IOException;public class MainActivity extends Activity {    private static final String SAMPLE = Environment.getExternalStorageDirectory() + "/test.aac";    protected static AudioDecoderThread mAudioDecoder;    private Button btn;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        btn = (Button) findViewById(R.id.play);        mAudioDecoder = new AudioDecoderThread();        btn.setOnClickListener(new OnClickListener() {            @Override            public void onClick(View view) {                try {                    mAudioDecoder.startPlay(SAMPLE);                } catch (IOException e) {                    e.printStackTrace();                }            }        });    }    @Override    protected void onStop() {        super.onStop();        mAudioDecoder.stop();    }}

2.AudioDecoderThread.java

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.util.Log;import java.io.IOException;import java.nio.ByteBuffer;public class AudioDecoderThread {    private static final int TIMEOUT_US = 1000;    private MediaExtractor mExtractor;    private MediaCodec mDecoder;    private boolean eosReceived;    private int mSampleRate = 0;    int channel = 0;    private final String TAG = "AACPlay";    public void startPlay(String path) throws IOException {        eosReceived = false;        //创建MediaExtractor对象用来解AAC封装        mExtractor = new MediaExtractor();        try {            //设置需要MediaExtractor解析的文件的路径            mExtractor.setDataSource(path);        } catch (IOException e) {            e.printStackTrace();        }            MediaFormat format = mExtractor.getTrackFormat(0);            if (format == null)            {                Log.e(TAG,"format is null");                return;            }            //判断当前帧的文件类型是否为audio            String mime = format.getString(MediaFormat.KEY_MIME);            if (mime.startsWith("audio/")) {                Log.d(TAG, "format : " + format);                //获取当前帧的采样率                mExtractor.selectTrack(0);                mSampleRate = format.getInteger(MediaFormat.KEY_SAMPLE_RATE);                //获取当前帧的通道数                channel = format.getInteger(MediaFormat.KEY_CHANNEL_COUNT);                //音频文件长度                long duration = format.getLong(MediaFormat.KEY_DURATION);                Log.d(TAG,"length:"+duration/1000000);            }        //创建MediaCodec对象        mDecoder = MediaCodec.createDecoderByType(mime);        //配置MediaCodec        mDecoder.configure(format, null, null, 0);        if (mDecoder == null) {            Log.e(TAG, "Can't find video info!");            return;        }        //启动MediaCodec        mDecoder.start();        new Thread(AACDecoderAndPlayRunnable).start();    }    Runnable AACDecoderAndPlayRunnable = new Runnable() {        @Override        public void run() {            AACDecoderAndPlay();        }    };    public void AACDecoderAndPlay() {        ByteBuffer[] inputBuffers = mDecoder.getInputBuffers();        ByteBuffer[] outputBuffers = mDecoder.getOutputBuffers();        BufferInfo info = new BufferInfo();        int buffsize = AudioTrack.getMinBufferSize(mSampleRate, AudioFormat.CHANNEL_OUT_STEREO, AudioFormat.ENCODING_PCM_16BIT);        // 创建AudioTrack对象        AudioTrack audioTrack = new AudioTrack(AudioManager.STREAM_MUSIC, mSampleRate,                AudioFormat.CHANNEL_OUT_STEREO,                AudioFormat.ENCODING_PCM_16BIT,                buffsize,                AudioTrack.MODE_STREAM);        //启动AudioTrack        audioTrack.play();        while (!eosReceived) {            int inIndex = mDecoder.dequeueInputBuffer(TIMEOUT_US);            if (inIndex >= 0) {                ByteBuffer buffer = inputBuffers[inIndex];                //从MediaExtractor中读取一帧待解数据                int sampleSize = mExtractor.readSampleData(buffer, 0);                if (sampleSize < 0) {                    // We shouldn't stop the playback at this point, just pass the EOS                    // flag to mDecoder, we will get it again from the                    // dequeueOutputBuffer                    Log.d(TAG, "InputBuffer BUFFER_FLAG_END_OF_STREAM");                    mDecoder.queueInputBuffer(inIndex, 0, 0, 0, MediaCodec.BUFFER_FLAG_END_OF_STREAM);                } else {                    //向MediaDecoder输入一帧待解码数据                    mDecoder.queueInputBuffer(inIndex, 0, sampleSize, mExtractor.getSampleTime(), 0);                    mExtractor.advance();                }                //从MediaDecoder队列取出一帧解码后的数据                int outIndex = mDecoder.dequeueOutputBuffer(info, TIMEOUT_US);                switch (outIndex) {                    case MediaCodec.INFO_OUTPUT_BUFFERS_CHANGED:                        Log.d(TAG, "INFO_OUTPUT_BUFFERS_CHANGED");                        outputBuffers = mDecoder.getOutputBuffers();                        break;                    case MediaCodec.INFO_OUTPUT_FORMAT_CHANGED:                        MediaFormat format = mDecoder.getOutputFormat();                        Log.d(TAG, "New format " + format);                        audioTrack.setPlaybackRate(format.getInteger(MediaFormat.KEY_SAMPLE_RATE));                        break;                    case MediaCodec.INFO_TRY_AGAIN_LATER:                        Log.d(TAG, "dequeueOutputBuffer timed out!");                        break;                    default:                        ByteBuffer outBuffer = outputBuffers[outIndex];                        //Log.v(TAG, "outBuffer: " + outBuffer);                        final byte[] chunk = new byte[info.size];                        // Read the buffer all at once                        outBuffer.get(chunk);                        //清空buffer,否则下一次得到的还会得到同样的buffer                        outBuffer.clear();                        // AudioTrack write data                        audioTrack.write(chunk, info.offset, info.offset + info.size);                        mDecoder.releaseOutputBuffer(outIndex, false);                        break;                }                // 所有帧都解码、播放完之后退出循环                if ((info.flags & MediaCodec.BUFFER_FLAG_END_OF_STREAM) != 0) {                    Log.d(TAG, "OutputBuffer BUFFER_FLAG_END_OF_STREAM");                    break;                }            }        }        //释放MediaDecoder资源        mDecoder.stop();        mDecoder.release();        mDecoder = null;        //释放MediaExtractor资源        mExtractor.release();        mExtractor = null;        //释放AudioTrack资源        audioTrack.stop();        audioTrack.release();        audioTrack = null;    }    public void stop() {        eosReceived = true;    }}

3.activity_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="vertical">    <Button        android:id="@+id/play"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:text="Play" /></LinearLayout>