For
the pSrcHdr field of CODECOPEN it
contains the video stream palette. For the pDstHdr field of CODECOPEN
it contains the destination color space (for example, the physical palette
if the CODEC_DIRECT_DISPLAY capability flag is set). The ulStartIndex
field of the GENPAL structure is always
NULL. The prgb2Entries field of the GENPAL
structure is NULL when the number of colors exceeds 256.