項目地址
https://github.com/979451341/OpenSLAudio 

OpenSL ES 是基於NDK也就是c語言的底層開發音頻的公開API，通過使用它能夠做到標準化, 高性能,低響應時間的音頻功能實現方法。

這次是使用OpenSL ES來做一個音樂播放器，它能夠播放m4a、mp3文件，並能夠暫停和調整音量

播放音樂需要做一些步驟

1.創建聲音引擎

首先創建聲音引擎的對象介面 
    result = slCreateEngine(&engineObject, 0, NULL, 0, NULL, NULL);

然後實現它
    result = (*engineObject)->Realize(engineObject, SL_BOOLEAN_FALSE);

從聲音引擎的對象中抓取聲音引擎
    result = (*engineObject)->GetInterface(engineObject, SL_IID_ENGINE, &engineEngine);

創建"輸出混音器"
    result = (*engineEngine)->CreateOutputMix(engineEngine, &outputMixObject, 1, ids, req);

實現輸出混合音
    result = (*outputMixObject)->Realize(outputMixObject, SL_BOOLEAN_FALSE);

2.創建聲音播放器

創建和實現播放器

    // realize the player
    result = (*bqPlayerObject)->Realize(bqPlayerObject, SL_BOOLEAN_FALSE);
    assert(SL_RESULT_SUCCESS == result);
    (void)result;

    // get the play interface
    result = (*bqPlayerObject)->GetInterface(bqPlayerObject, SL_IID_PLAY, &bqPlayerPlay);
    assert(SL_RESULT_SUCCESS == result);
    (void)result;

3.設置播放緩衝

數據格式配置

    SLDataFormat_PCM format_pcm = {SL_DATAFORMAT_PCM, 1, SL_SAMPLINGRATE_8,
                                   SL_PCMSAMPLEFORMAT_FIXED_16, SL_PCMSAMPLEFORMAT_FIXED_16,
                                   SL_SPEAKER_FRONT_CENTER, SL_BYTEORDER_LITTLEENDIAN};

數據定位器 就是定位要播放聲音數據的存放位置，分為4種：記憶體位置，輸入/輸出設備位置，緩衝區隊列位置，和midi緩衝區隊列位置。

數據定位器配置

    SLDataLocator_AndroidSimpleBufferQueue loc_bufq = {SL_DATALOCATOR_ANDROIDSIMPLEBUFFERQUEUE, 2};

得到了緩存隊列介面，並註冊

    // get the buffer queue interface
    result = (*bqPlayerObject)->GetInterface(bqPlayerObject, SL_IID_BUFFERQUEUE,
                                             &bqPlayerBufferQueue);
    assert(SL_RESULT_SUCCESS == result);
    (void)result;

    // register callback on the buffer queue
    result = (*bqPlayerBufferQueue)->RegisterCallback(bqPlayerBufferQueue, bqPlayerCallback, NULL);
    assert(SL_RESULT_SUCCESS == result);
    (void)result;

4.獲得其他介面用來控制播放

得到聲音特效介面

    // get the effect send interface
    result = (*bqPlayerObject)->GetInterface(bqPlayerObject, SL_IID_EFFECTSEND,
                                             &bqPlayerEffectSend);
    assert(SL_RESULT_SUCCESS == result);
    (void)result;

得到音量介面

    // get the volume interface
    result = (*bqPlayerObject)->GetInterface(bqPlayerObject, SL_IID_VOLUME, &bqPlayerVolume);
    assert(SL_RESULT_SUCCESS == result);
    (void)result;

    // set the player's state to playing
    result = (*bqPlayerPlay)->SetPlayState(bqPlayerPlay, SL_PLAYSTATE_PLAYING);
    assert(SL_RESULT_SUCCESS == result);
    (void)result;

5.提供播放數據

打開音樂文件

    // convert Java string to UTF-8
    const char *utf8 = (*env)->GetStringUTFChars(env, filename, NULL);
    assert(NULL != utf8);

    // use asset manager to open asset by filename
    AAssetManager* mgr = AAssetManager_fromJava(env, assetManager);
    assert(NULL != mgr);
    AAsset* asset = AAssetManager_open(mgr, utf8, AASSET_MODE_UNKNOWN);

    // release the Java string and UTF-8
    (*env)->ReleaseStringUTFChars(env, filename, utf8);

    // the asset might not be found
    if (NULL == asset) {
        return JNI_FALSE;
    }

    // open asset as file descriptor
    off_t start, length;
    int fd = AAsset_openFileDescriptor(asset, &start, &length);
    assert(0 <= fd);
    AAsset_close(asset);

設置播放數據

    SLDataLocator_AndroidFD loc_fd = {SL_DATALOCATOR_ANDROIDFD, fd, start, length};
    SLDataFormat_MIME format_mime = {SL_DATAFORMAT_MIME, NULL, SL_CONTAINERTYPE_UNSPECIFIED};
    SLDataSource audioSrc = {&loc_fd, &format_mime};

6.播放音樂

播放音樂只需要通過播放介面改變播放狀態就可以了,暫停也是，停止也是，但是暫停必須之前的播放緩存做了才行，否則那暫停就相當於停止了

        result = (*fdPlayerPlay)->SetPlayState(fdPlayerPlay, isPlaying ?
                                                             SL_PLAYSTATE_PLAYING : SL_PLAYSTATE_PAUSED);

7.調解音量

SLVolumeItf getVolume()
{
    if (fdPlayerVolume != NULL)
        return fdPlayerVolume;
    else
        return bqPlayerVolume;
}

void Java_com_ywl5320_openslaudio_MainActivity_setVolumeAudioPlayer(JNIEnv* env, jclass clazz,
                                                                      jint millibel)
{
    SLresult result;
    SLVolumeItf volumeItf = getVolume();
    if (NULL != volumeItf) {
        result = (*volumeItf)->SetVolumeLevel(volumeItf, millibel);
        assert(SL_RESULT_SUCCESS == result);
        (void)result;
    }
}

8.釋放資源

關閉app時釋放占用資源

void Java_com_ywl5320_openslaudio_MainActivity_shutdown(JNIEnv* env, jclass clazz)
{

    // destroy buffer queue audio player object, and invalidate all associated interfaces
    if (bqPlayerObject != NULL) {
        (*bqPlayerObject)->Destroy(bqPlayerObject);
        bqPlayerObject = NULL;
        bqPlayerPlay = NULL;
        bqPlayerBufferQueue = NULL;
        bqPlayerEffectSend = NULL;
        bqPlayerMuteSolo = NULL;
        bqPlayerVolume = NULL;
    }

    // destroy file descriptor audio player object, and invalidate all associated interfaces
    if (fdPlayerObject != NULL) {
        (*fdPlayerObject)->Destroy(fdPlayerObject);
        fdPlayerObject = NULL;
        fdPlayerPlay = NULL;
        fdPlayerSeek = NULL;
        fdPlayerMuteSolo = NULL;
        fdPlayerVolume = NULL;
    }



    // destroy output mix object, and invalidate all associated interfaces
    if (outputMixObject != NULL) {
        (*outputMixObject)->Destroy(outputMixObject);
        outputMixObject = NULL;
        outputMixEnvironmentalReverb = NULL;
    }

    // destroy engine object, and invalidate all associated interfaces
    if (engineObject != NULL) {
        (*engineObject)->Destroy(engineObject);
        engineObject = NULL;
        engineEngine = NULL;
    }

}

參考文章
http://blog.csdn.net/u013898698/article/details/72822595

http://blog.csdn.net/ywl5320/article/details/78503768