HRESULT SetFormat(LPWAVEFORMATEX lpfxFormat);
Sets the format of the primary sound buffer for the application. Whenever this application has the input focus, DirectSound will set the primary buffer to the specified format.
·Returns DS_OK if successful, or one of the following error values otherwise:
lpfxFormat
Address of a WAVEFORMATEX structure that describes the new format for the primary sound buffer.
If this method is called on a primary buffer that is being accessed in write-primary cooperative level, the buffer must be stopped before IDirectSoundBuffer::SetFormat is called. If this method is being called on a primary buffer for a non-write-primary level, DirectSound will implicitly stop the primary buffer, change the format, and restart the primary; the application need not do this explicitly.
A call to this method fails if the hardware does not directly support the requested pulse coded modulation (PCM) format. It will also fail if the calling application has the DSSCL_NORMAL cooperative level.
If a secondary sound buffer requires a format change, the application should create a new DirectSoundBuffer object using the new format.
DirectSound supports PCM formats; it does not currently support compressed formats.