directsound的一个简单问题

[dqxian]

我想在播放音频的时候动态的改变播放的频率，应该调用什么函数？什么操作？
是不是调用IDirectSoundBuffer8::SetFrequency(Freq)函数呀？如果是的话
应该在什么地方加呢？是在往DirectSound Buffer添加数据(即Lock()函数前面)
还是在播放的时候m_pDSB->play(0,0,0)前面加？还有哪些参数要注意修改？

[dqxian]

哦，谢谢楼上的回复

[hugeice]

以前用的时候好像是可以随时修改播放频率, 不过不能修改主缓冲的播放频率, MSDN上说的, 参见 http://msdn.microsoft.com/archive/default.asp?url=/archive/en-us/directx9_c/directx/htm/idirectsoundbuffer8setfrequency.asp

Remarks

Increasing or decreasing the frequency changes the perceived pitch of the audio data. This method does not affect the format of the buffer.

Before setting the frequency, you should ascertain whether the frequency is supported by checking the dwMinSecondarySampleRate and dwMaxSecondarySampleRate members of the DSCAPS structure for the device. Some operating systems do not support frequencies greater than 100,000 Hz.

This method is not valid for the primary buffer.