ICM_DECOMPRESSEX_BEGIN

  • Article

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

Pointer to 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.

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, ICDECOMPRESSEX, ICM_DECOMPRESSEX, ICM_DECOMPRESSEX_END, ICM_DRAW_BEGIN