See also ICM_COMPRESS, ICM_COMPRESS_END, ICM_DECOMPRESS_BEGIN, ICM_DRAW_BEGIN
wParam = (DWORD) (LPVOID) lpbiInput; lParam = (DWORD) (LPVOID) lpbiOutput;
Notifies a video compression driver to prepare to compress data.
wParam
Address of a BITMAPINFO structure indicating the input format.
lParam
Address of a BITMAPINFO structure indicating the output format.
The driver should allocate and initialize any tables or memory that it needs for compressing the data formats when it receives the ICM_COMPRESS message.
VCM saves the settings of the most recent ICM_COMPRESS_BEGIN message. ICM_COMPRESS_BEGIN and ICM_COMPRESS_END 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.