android AAC的音频硬解码

上一篇写了AAC音频的硬编码，今天补充硬解码，其实就是硬编码反过来，非常简单

初始化AAC硬解码资源：

public int Start() {

int iRet = 0;

_miVersion = android.os.Build.VERSION.SDK_INT;

if(_miVersion < 16) {

iRet = ErrorInfo.ERR_ANDROID_VER_NOT_SUPPORT;

return iRet;

}

if(mMediaDecode != null) {

return ErrorInfo.ERR_MEDIACODEC_EXIST_ALREADY;

}

if(_audioTrack != null) {

return ErrorInfo.ERR_AUDIOTRACK_EXIST_ALREADY;

}

mMediaDecode = MediaCodec.createDecoderByType("audio/mp4a-latm");

MediaFormat format = new MediaFormat();

format.setString(MediaFormat.KEY_MIME, "audio/mp4a-latm");

format.setInteger(MediaFormat.KEY_CHANNEL_COUNT, 1);

format.setInteger(MediaFormat.KEY_SAMPLE_RATE, _miSamplingRate);

format.setInteger(MediaFormat.KEY_BIT_RATE, _miBitRate);

format.setInteger(MediaFormat.KEY_AAC_PROFILE, MediaCodecInfo.CodecProfileLevel.AACObjectLC);

mMediaDecode.configure(format, null, null, 0);

mMediaDecode.start();

_audioTrack = new MyAudioTrack(8000, AudioFormat.CHANNEL_OUT_MONO,

AudioFormat.ENCODING_PCM_16BIT);

_audioTrack.init();

inputBuffers = mMediaDecode.getInputBuffers();

outputBuffers = mMediaDecode.getOutputBuffers();

try {

Thread.sleep(200);

} catch (InterruptedException e) {

e.printStackTrace();

}

_mbStartFlag = true;

_mbInitFlag  = false;

return iRet;

}

对收到的AAC数据进行解码，并用_audioTrack进行播放：

需要注意的是， AAC音频第一个报文开始是一个两个字节的数据(0x15，0xF8)，需要自己手动填写以下：

public void DecodeAudio(byte[] audioData) {

int iRet = 0;     _miVersion = android.os.Build.VERSION.SDK_INT;     if(_miVersion < 16) {     return;     }     if(audioData == null) { return; }     if(!_mbStartFlag) {     return;     } int iAudioDataLen = audioData.length; try {        inputBufferIndex = mMediaDecode.dequeueInputBuffer(WAIT_TIME);        if (inputBufferIndex >= 0)        {            inputBuffer = inputBuffers[inputBufferIndex];            inputBuffer.clear();         if(_mbInitFlag == false) {         _mbInitFlag = true;         byte[] fisrtData = new byte[2];         fisrtData[0] = 21;         fisrtData[1] = -120;         inputBuffer.put(fisrtData);         }else {         inputBuffer.put(audioData);         }                    mMediaDecode.queueInputBuffer(inputBufferIndex, 0, iAudioDataLen, System.nanoTime()/1000, 0);        }        outputBufferIndex = mMediaDecode.dequeueOutputBuffer(bufferInfo, WAIT_TIME);        while (outputBufferIndex >= 0)        {            outputBuffer = outputBuffers[outputBufferIndex];            outputBuffer.position(0);            outData = new byte[bufferInfo.size];            outputBuffer.get(outData);            Log.d(TAG, outData.length + " bytes decoded"); if (_audioTrack != null) { _audioTrack.playAudioTrack(outData, 0, outData.length); }            mMediaDecode.releaseOutputBuffer(outputBufferIndex, false);            outputBufferIndex = mMediaDecode.dequeueOutputBuffer(bufferInfo, WAIT_TIME);        } } catch (Exception e) { Log.e(TAG, "Exception: "+Log.getStackTraceString(e)); }              return;     }