The ICM_COMPRESS_BEGIN message is sent to a video compression driver to prepare it for compressing data.
Parameters
dwParam1
Specifies a pointer to a BITMAPINFO data structure indicating the input format.
dwParam2
Specifies a pointer to a BITMAPINFO data structure indicating the output format.
Return Value
Returns ICERR_OK if the specified compression is supported. Otherwise, returns ICERR_BADFORMAT if the input or output format is not supported.
Comments
The driver should set up any tables or memory that it needs to compress the data formats efficiently when it receives the ICM_COMPRESS message.
The ICM_COMPRESS_BEGIN and ICM_COMPRESS_END messages do not nest. If your driver receives an ICM_COMPRESS_BEGIN message before compression is stopped with ICM_COMPRESS_END, it should restart compression with new parameters.