ICM_COMPRESS_BEGIN
The
ICM_COMPRESS_BEGIN message notifies a video compression driver to prepare to
compress data. You can send this message explicitly or by using the ICCompressBegin macro.
ICM_COMPRESS_BEGIN
wParam = (DWORD) (LPVOID) lpbiInput;
lParam = (DWORD) (LPVOID) lpbiOutput;
Parameters
lpbiInput
Address of a BITMAPINFO structure containing the
input format.
lpbiOutput
Address of a BITMAPINFO
structure containing the output format.
Return Values
Returns
ICERR_OK if the driver supports the specified compression or ICERR_BADFORMAT if
the input or output format is not supported.
Remarks
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. The ICM_COMPRESS_BEGIN
and ICM_COMPRESS_END messages do not nest. If your driver receives
ICM_COMPRESS_BEGIN before compression is stopped with ICM_COMPRESS_END, it
should restart compression with new parameters.
See Also