ICM_DECOMPRESSEX_BEGIN message

The ICM_DECOMPRESSEX_BEGIN message notifies a video compression driver to prepare to decompress data.

ICM_DECOMPRESSEX_BEGIN 
wParam = (DWORD_PTR) (LPVOID) &icdex; 
lParam = sizeof(ICDECOMPRESSEX); 

Parameters

icdex

Pointer to a ICDECOMPRESSEX structure containing the input and output formats.

lParam

Size, in bytes, of ICDECOMPRESSEX.

Return Value

Returns ICERR_OK if the specified decompression is supported or ICERR_BADFORMAT otherwise.

Remarks

When the driver receives this message, it should allocate buffers and do any time-consuming operations so that it can process ICM_DECOMPRESSEX messages efficiently.

If you want the driver to decompress data directly to the screen, send the ICM_DRAW_BEGIN message.

The ICM_DECOMPRESSEX_BEGIN and ICM_DECOMPRESSEX_END messages do not nest. If your driver receives ICM_DECOMPRESSEX_BEGIN before decompression is stopped with ICM_DECOMPRESSEX_END, it should restart decompression with new parameters.

Requirements

Requirement	Value
Minimum supported client	Windows 2000 Professional [desktop apps only]
Minimum supported server	Windows 2000 Server [desktop apps only]
Header	Vfw.h

See also

Video Compression Manager

Video Compression Messages