ICM_DECOMPRESSEX_BEGIN

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

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

Parameters

icdex

Address of a ICDECOMPRESSEX structure containing the input and output formats.

lParam

Size, in bytes, of ICDECOMPRESSEX.

Return Values

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.

QuickInfo

  Windows NT: Requires version 3.1 or later.
  Windows: Requires Windows 95 or later.
  Windows CE: Unsupported.
  Header: Declared in vfw.h.

See Also

Video Compression Manager Overview, Video Compression Messages, ICDECOMPRESSEX, ICM_DECOMPRESSEX, ICM_DECOMPRESSEX_END, ICM_DRAW_BEGIN