如何在XAudio2上同时播放多个声音？

Question

我目前正在尝试用XAudio2在Windows中制作一个游戏应用，但我不知道如何让应用在播放声音时不会被阻塞。我尝试在this repository.的示例中调用一个新线程

但这只会导致错误。我尝试在函数中传递一个对主控声音的引用，但它只是引发了一个"XAudio2:必须首先创建一个主控声音“错误。我是不是遗漏了什么？我只是想让它同时播放两个声音，并从那里构建。我看了一下文档，但它非常模糊。

Answer 1

XAudio2是一个非阻塞的API。要同时播放两个声音，您至少需要两个“源声音”和一个“掌握声音”。

DX::ThrowIfFailed(
    CoInitializeEx( nullptr, COINIT_MULTITHREADED )
);

Microsoft::WRL::ComPtr<IXAudio2> pXAudio2;
// Note that only IXAudio2 (and APOs) are COM reference counted
DX::ThrowIfFailed(
    XAudio2Create( pXAudio2.GetAddressOf(), 0 )
);

IXAudio2MasteringVoice* pMasteringVoice = nullptr;
DX::ThrowIfFailed(
    pXAudio2->CreateMasteringVoice( &pMasteringVoice )
);

IXAudio2SourceVoice* pSourceVoice1 = nullptr;
DX::ThrowIfFailed(
    pXaudio2->CreateSourceVoice( &pSourceVoice1, &wfx ) )
    // The default 'pSendList' will be just to the pMasteringVoice
);

IXAudio2SourceVoice* pSourceVoice2 = nullptr;
DX::ThrowIfFailed(
    pXaudio2->CreateSourceVoice( &pSourceVoice2, &wfx) )
    // Doesn't have to be same format as other source voice
    // And doesn't have to match the mastering voice either
);

DX::ThrowIfFailed(
    pSourceVoice1->SubmitSourceBuffer( &buffer )
);

DX::ThrowIfFailed(
    pSourceVoice2->SubmitSourceBuffer( &buffer /* could be different WAV data or not */)
);

DX::ThrowIfFailed(
    pSourceVoice1->Start( 0 );
);

DX::ThrowIfFailed(
    pSourceVoice2->Start( 0 );
);

您应该看看GitHub和DirectX Tool Kit for Audio上的示例

如果你想确保两个源声音同时开始，你可以使用：

DX::ThrowIfFailed(
    pSourceVoice1->Start( 0, 1 );
);

DX::ThrowIfFailed(
    pSourceVoice2->Start( 0, 1 );
);

DX::ThrowIfFailed(
    pSourceVoice2->CommitChanges( 1 );
);

Answer 2

如果您想同时播放多个声音，可以使用playSound函数并启动各种线程来播放不同的声音，每个声音都是特定的源声音。

XAudio2将负责将每个声音映射到可用的通道(或者，如果您有更高级的系统，您可以使用IXAudio2Voice::SetOutputMatrix自己指定映射)。

void playSound( IXAudio2SourceVoice* sourceVoice )
{
    BOOL isPlayingSound = TRUE;
    XAUDIO2_VOICE_STATE soundState = {0};
    HRESULT hres = sourceVoice->Start( 0u );
    while ( SUCCEEDED( hres ) && isPlayingSound )
    {// loop till sound completion
        sourceVoice->GetState( &soundState );
        isPlayingSound = ( soundState.BuffersQueued > 0 ) != 0;
        Sleep( 100 );
    }
}

例如，同时播放两个声音：

IXAudio2SourceVoice* pSourceVoice1 = nullptr;
IXAudio2SourceVoice* pSourceVoice2 = nullptr;

// setup the source voices, load the sounds etc..

std::thread thr1{ playSound, pSourceVoice1 };
std::thread thr2{ playSound, pSourceVoice2 };

thr1.join();
thr2.join();