attachAuxEffect and OpenSL ES

Question

在Android中使用AudioTrack时，可以调用attachAuxEffect来附加音频效果。在使用OpenSL ES进行音频播放时，是否有类似的方法或方法？我似乎找不到类似的方法。

Answer 1

有一个如何在NDK home/samples/native audio目录中使用OpenSL ES原生音频的示例。

看看这段代码（我们在这里应用混响效果）：

...
// create the engine and output mix objects
void Java_com_example_nativeaudio_NativeAudio_createEngine(JNIEnv* env, jclass clazz)
{
    SLresult result;
    // create engine
    result = slCreateEngine(&engineObject, 0, NULL, 0, NULL, NULL);
    assert(SL_RESULT_SUCCESS == result);
    (void)result;
    // realize the engine
    result = (*engineObject)->Realize(engineObject, SL_BOOLEAN_FALSE);
    assert(SL_RESULT_SUCCESS == result);
    (void)result;
    // get the engine interface, which is needed in order to create other objects
    result = (*engineObject)->GetInterface(engineObject, SL_IID_ENGINE, &engineEngine);
    assert(SL_RESULT_SUCCESS == result);
    (void)result;
    // create output mix, with environmental reverb specified as a non-required interface
    const SLInterfaceID ids[1] = {SL_IID_ENVIRONMENTALREVERB};
    const SLboolean req[1] = {SL_BOOLEAN_FALSE};
    result = (*engineEngine)->CreateOutputMix(engineEngine, &outputMixObject, 1, ids, req);
    assert(SL_RESULT_SUCCESS == result);
    (void)result;
    // realize the output mix
    result = (*outputMixObject)->Realize(outputMixObject, SL_BOOLEAN_FALSE);
    assert(SL_RESULT_SUCCESS == result);
    (void)result;
    // get the environmental reverb interface
    // this could fail if the environmental reverb effect is not available,
    // either because the feature is not present, excessive CPU load, or
    // the required MODIFY_AUDIO_SETTINGS permission was not requested and granted
    result = (*outputMixObject)->GetInterface(outputMixObject, SL_IID_ENVIRONMENTALREVERB,
            &outputMixEnvironmentalReverb);
    if (SL_RESULT_SUCCESS == result) {
        result = (*outputMixEnvironmentalReverb)->SetEnvironmentalReverbProperties(
                outputMixEnvironmentalReverb, &reverbSettings);
        (void)result;
    }
    // ignore unsuccessful result codes for environmental reverb, as it is optional for this example
}

请注意Android OpenSL ES实现是OpenSL ES的子集，后者是OpenSL的子集：某些效果可能在所有设备上都不可用。这方面的一个非常简短的解释可以在这里找到。