ICM_DECOMPRESSEX_BEGIN

See also ICM_DECOMPRESSEX, ICM_DECOMPRESSEX_END, ICM_DRAW_BEGIN

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

Notifies a video compression driver to prepare to decompress data.

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

wParam

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

lParam

Size, in bytes, of a ICDECOMPRESSEX structure.

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.

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