ICM_COMPRESS_BEGIN

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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

Pointer to a BITMAPINFO structure containing the input format.

lpbiOutput

Pointer to 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.

Requirements

**  Windows NT/2000/XP:** Included in Windows NT 3.1 and later.
**  Windows 95/98/Me:** Included in Windows 95 and later.
**  Header:** Declared in Vfw.h.

See Also

Video Compression Manager, Video Compression Messages, BITMAPINFO, ICM_COMPRESS, ICM_COMPRESS_END, ICCompressBegin