The ICM_GETBUFFERSWANTED message is sent to a video compression driver to have it return information about how many samples the driver will pre-buffer.
Parameters
dwParam1
Specifies a pointer to a DWORD. The driver uses the DWORD to return the number of samples it needs to get in advance of when they will be presented.
dwParam2
Not used.
Return Value
Returns ICERR_OK if successful. Otherwise, returns ICERR_UNSUPPORTED.
Comments
Typically, this message is only used by a driver that uses hardware to render data and must ensure hardware pipelines remain full. For example, if a driver controls a video decompression board that can hold ten frames of video, it could return ten for this message. This instructs an application to try and stay ten frames ahead of the frame it currently needs.