播放器基础--OpenSL ES音频播放

target_link_libraries( # Specifies the target library.
   
        OpenSLES

        )

   //引擎
    SLObjectItf engineObject = 0;
    //引擎接口
    SLEngineItf engineInterface = 0;
    //混音器
    SLObjectItf outputMixObject = 0;
    //播放器
    SLObjectItf bqPlayerObject = 0;
    //播放器接口
    SLPlayItf bqPlayerPlay = 0;
    //播放器队列接口
    SLAndroidSimpleBufferQueueItf bqPlayerBufferQueue = 0;

void AudioChannel::audio_play() {
    /**
     * 1、创建引擎并获取引擎接口
     */
    SLresult result;
    // 1.1 创建引擎对象：SLObjectItf engineObject
    result = slCreateEngine(&engineObject, 0, NULL, 0, NULL, NULL);
    if (SL_RESULT_SUCCESS != result) {
        return;
    }
    // 1.2 初始化引擎
    result = (*engineObject)->Realize(engineObject, SL_BOOLEAN_FALSE);
    if (SL_RESULT_SUCCESS != result) {
        return;
    }
    // 1.3 获取引擎接口 SLEngineItf engineInterface
    result = (*engineObject)->GetInterface(engineObject, SL_IID_ENGINE, &engineInterface);
    if (SL_RESULT_SUCCESS != result) {
        return;
    }
    /**
     * 2、设置混音器
     */
    // 2.1 创建混音器：SLObjectItf outputMixObject
    result = (*engineInterface)->CreateOutputMix(engineInterface, &outputMixObject, 0,
                                                 0, 0);
    if (SL_RESULT_SUCCESS != result) {
        return;
    }
    // 2.2 初始化混音器
    result = (*outputMixObject)->Realize(outputMixObject, SL_BOOLEAN_FALSE);
    if (SL_RESULT_SUCCESS != result) {
        return;
    }
    /**
     * 3、创建播放器
     */
    //3.1 配置输入声音信息
    //创建buffer缓冲类型的队列 2个队列
    SLDataLocator_AndroidSimpleBufferQueue loc_bufq = {SL_DATALOCATOR_ANDROIDSIMPLEBUFFERQUEUE,
                                                       2};
    //pcm数据格式
    //SL_DATAFORMAT_PCM：数据格式为pcm格式
    //2：双声道
    //SL_SAMPLINGRATE_44_1：采样率为44100
    //SL_PCMSAMPLEFORMAT_FIXED_16：采样格式为16bit
    //SL_PCMSAMPLEFORMAT_FIXED_16：数据大小为16bit
    //SL_SPEAKER_FRONT_LEFT | SL_SPEAKER_FRONT_RIGHT：左右声道（双声道）
    //SL_BYTEORDER_LITTLEENDIAN：小端模式
    SLDataFormat_PCM format_pcm = {SL_DATAFORMAT_PCM, 2, SL_SAMPLINGRATE_44_1,
                                   SL_PCMSAMPLEFORMAT_FIXED_16,
                                   SL_PCMSAMPLEFORMAT_FIXED_16,
                                   SL_SPEAKER_FRONT_LEFT | SL_SPEAKER_FRONT_RIGHT,
                                   SL_BYTEORDER_LITTLEENDIAN};

    //数据源 将上述配置信息放到这个数据源中
    SLDataSource audioSrc = {&loc_bufq, &format_pcm};

    //3.2 配置音轨（输出）
    //设置混音器
    SLDataLocator_OutputMix loc_outmix = {SL_DATALOCATOR_OUTPUTMIX, outputMixObject};
    SLDataSink audioSnk = {&loc_outmix, NULL};
    //需要的接口 操作队列的接口
    const SLInterfaceID ids[1] = {SL_IID_BUFFERQUEUE};
    const SLboolean req[1] = {SL_BOOLEAN_TRUE};
    //3.3 创建播放器
    result = (*engineInterface)->CreateAudioPlayer(engineInterface, &bqPlayerObject, &audioSrc,
                                                   &audioSnk, 1, ids, req);
    if (SL_RESULT_SUCCESS != result) {
        return;
    }
    //3.4 初始化播放器：SLObjectItf bqPlayerObject
    result = (*bqPlayerObject)->Realize(bqPlayerObject, SL_BOOLEAN_FALSE);
    if (SL_RESULT_SUCCESS != result) {
        return;
    }
    //3.5 获取播放器接口：SLPlayItf bqPlayerPlay
    result = (*bqPlayerObject)->GetInterface(bqPlayerObject, SL_IID_PLAY, &bqPlayerPlay);
    if (SL_RESULT_SUCCESS != result) {
        return;
    }
    /**
     * 4、设置播放回调函数
     */
    //4.1 获取播放器队列接口：SLAndroidSimpleBufferQueueItf bqPlayerBufferQueue
    (*bqPlayerObject)->GetInterface(bqPlayerObject, SL_IID_BUFFERQUEUE, &bqPlayerBufferQueue);

    //4.2 设置回调 void bqPlayerCallback(SLAndroidSimpleBufferQueueItf bq, void *context)
    (*bqPlayerBufferQueue)->RegisterCallback(bqPlayerBufferQueue, bqPlayerCallback, this);

    /**
     * 5、设置播放器状态为播放状态
     */
    (*bqPlayerPlay)->SetPlayState(bqPlayerPlay, SL_PLAYSTATE_PLAYING);

    /**
     * 6、手动激活回调函数
     */
    bqPlayerCallback(bqPlayerBufferQueue, this);
}

void bqPlayerCallback(SLAndroidSimpleBufferQueueItf bq, void *context) {
    AudioChannel *audioChannel = static_cast<AudioChannel *>(context);
    int pcm_size = audioChannel->getPCM();
    if (pcm_size > 0) {
        (*bq)->Enqueue(bq, audioChannel->out_buffers, pcm_size);
    }
}