为什么 OpenSL ES 不会在每次启动应用程序时播放音频

Why OpenSL ES won't play audio every time an application is started

本文关键字：应用程序 启动 播放 音频 ES OpenSL 为什么      更新时间：2023-10-16

我正在使用Android上的OpenSL ES在游戏引擎中实现音频播放。到目前为止，我仅支持Android文件描述符数据定位器（AndroidFD）。问题是，如果我在Opensles。epensles。

包装纸：

audioEngine.cpp 

AudioEngine::AudioEngine()
    : _engine(NULL),
      _engineInterface(NULL),
      _outputMix(NULL)
{
    createEngine();
    createOutputMix();
}
AudioEngine::~AudioEngine()
{
    (*_outputMix)->Destroy(_outputMix);
    (*_engine)->Destroy(_engine);
}
Sound* AudioEngine::loadSound(const String& filename) const
{
    return NEW Sound(_engineInterface, _outputMix, filename);
}

// Private
void AudioEngine::createEngine()
{
    Uint32 result = slCreateEngine(&_engine, 0u, NULL, 0u, NULL, NULL);
    CHECK_OPENSLES_ERROR(result, "Platform::AudioEngine (OpenSLES)",
        "Failed to create the engine");
    result = (*_engine)->Realize(_engine, SL_BOOLEAN_FALSE);
    CHECK_OPENSLES_ERROR(result, "Platform::AudioEngine (OpenSLES)",
        "Failed to initialise the engine");
    result = (*_engine)->GetInterface(_engine, SL_IID_ENGINE, &_engineInterface);
    CHECK_OPENSLES_ERROR(result, "Platform::AudioEngine (OpenSLES)",
        "Failed to get the engine interface");
}
void AudioEngine::createOutputMix()
{
    Uint32 result = (*_engineInterface)->CreateOutputMix(_engineInterface, &_outputMix, 0u,
        NULL, NULL);
    CHECK_OPENSLES_ERROR(result, "Platform::AudioEngine (OpenSLES)",
        "Failed to create the output mix");
    result = (*_outputMix)->Realize(_outputMix, SL_BOOLEAN_FALSE);
    CHECK_OPENSLES_ERROR(result, "Platform::AudioEngine (OpenSLES)",
        "Failed to initialise the output mix");
}

sound.cpp 

// Public
Sound::Sound(SLEngineItf engineInterface, SLObjectItf outputMix, const String& filename)
    : _engineInterface(engineInterface),
      _outputMix(outputMix),
      _player(NULL),
      _playerInterface(NULL)
{
    // Member (SLDataFormat_MIME)
    _dataSourceFormat.formatType = SL_DATAFORMAT_MIME;
    _dataSourceFormat.mimeType = NULL;
    _dataSourceFormat.containerType = SL_CONTAINERTYPE_UNSPECIFIED;
    // Member (SLDataLocator_AndroidFD)
    _dataSourceLocator.locatorType = SL_DATALOCATOR_ANDROIDFD;
    AAssetManager* assetManager = Application::assetManager();
    AAsset* asset = AAssetManager_open(assetManager, filename.data(), AASSET_MODE_UNKNOWN);
    _dataSourceLocator.fd = AAsset_openFileDescriptor(asset,
        reinterpret_cast<off_t*>(&_dataSourceLocator.offset),
        reinterpret_cast<off_t*>(&_dataSourceLocator.length));
    AAsset_close(asset);
    createPlayer();
}
Sound::~Sound()
{
    (*_player)->Destroy(_player);
}
void Sound::play() const
{
    const Uint32 result = (*_playerInterface)->SetPlayState(_playerInterface,
        SL_PLAYSTATE_PLAYING);
    CHECK_OPENSLES_ERROR(result, "Platform::Sound (OpenSLES)",
        "Failed to set the play state"); 
}

// Private
void Sound::createPlayer()
{
    SLDataSource dataSource =
    {
        &_dataSourceLocator,
        &_dataSourceFormat
    };
    SLDataLocator_OutputMix outputMixLocator =
    {
        SL_DATALOCATOR_OUTPUTMIX,
        _outputMix
    };
    SLDataSink dataSink =
    {
        &outputMixLocator,
        NULL
    };
    Uint32 result = (*_engineInterface)->CreateAudioPlayer(_engineInterface, &_player,
        &dataSource, &dataSink, 0u, NULL, NULL);
    CHECK_OPENSLES_ERROR(result, "Platform::Sound (OpenSLES)",
        "Failed to create a player");
    result = (*_player)->Realize(_player, SL_BOOLEAN_FALSE);
    CHECK_OPENSLES_ERROR(result, "Platform::Sound (OpenSLES)",
        "Failed to initialise the player");
    result = (*_player)->GetInterface(_player, SL_IID_PLAY, &_playerInterface);
    CHECK_OPENSLES_ERROR(result, "Platform::SoundInstance (OpenSLES)",
        "Failed to get the player interface");
}

game.cpp 

Game::initialise()
{
    _audioEngine = NEW AudioEngine();
    _sound = _audioEngine->loadSound("music.ogg");
    _sound->play();
}

应用程序启动时，声音将不会总是播放。如果我在游戏内部:: directise（）中写下所有opensl es代码，则声音将始终播放。我无法弄清楚为什么在包装器类中不使用相同的代码。

我在三星Galaxy S III（GT-I9305），Android 4.2.2，Cyanogenmod 10.1.3-I9305

上运行了应用程序。

在播放声音时，您可能必须将数据源，outputmixlocator和datasink保留在范围内，因为它们被作为指针传递。使它们成为成员变量，以使它们在物体的寿命中保持活力。

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