How to: Use Submix Voices

How to: Use Submix Voices：https://msdn.microsoft.com/en-us/library/windows/desktop/ee415794(v=vs.85).aspx

This topic shows you how you can set groups of voices to send their output to the same submix voice. This enables a single change to a submix voice to affect a whole group of voices.

这篇文章向你展示怎样设置一组声音，使它们的输出发送到同一个Submix Voice。这样能够实现一个Submix Voice一个改变能够影响一整组声音。

1.Create a submix voice to which all of the game's sound effect voices will send.

创建一个全部游戏声效都会输出到此的Submix Voice：

IXAudio2SubmixVoice * pSFXSubmixVoice;
pXAudio2->CreateSubmixVoice(&pSFXSubmixVoice,1,44100,0,0,0,0);

2.Create an XAUDIO2_VOICE_SENDS structure that contains a reference to the submix voice.

创建一个包括对Submix Voice引用的XAUDIO2_VOICE_SENDS结构体：

XAUDIO2_SEND_DESCRIPTOR SFXSend = {0, pSFXSubmixVoice};
XAUDIO2_VOICE_SENDS SFXSendList = {1, &SFXSend};

3.Pass the XAUDIO2_VOICE_SENDS structure to new source voices as they are created.

当创建Source Voices的时候，将XAUDIO2_VOICE_SENDS结构体传递给它们：

IXAudio2SourceVoice* pSFXSourceVoice;
if( FAILED(hr = pXaudio2->CreateSourceVoice( &pSFXSourceVoice, (WAVEFORMATEX*)&wfx,
    0, XAUDIO2_DEFAULT_FREQ_RATIO, pCallback, pSFXSendList, NULL ) ) )
    return hr;

4.Apply changes to all sound effect voices by adjusting the submix voice.

通过调节Submix Voice，改变全部和它有关联的声效：

In this example, changing the volume of the submix voice with the SetVolume function effectively changes the volume of all voices that output to it.

比如：使用SetVolume函数来改动Submix Voice的音量，能够有效得改变全部输出到它的voices的volume。

pSFXSubmixVoice->SetVolume(0.1);

交流QQ：1245178753