I have noticed that the H.264 encoder doesn't handle the transition from a still scene to a fast motion scene very well. In particular, the encoder doesn't send an IDR frame when we go to a fast motion scene and this results in one of two behaviors:
1) In CBR/VBR: You see a lot of artifacting and it looks very bad
2) In AVBR: The video looks good, however, at the point of transition to fast motion, the encoder generates several very large P frames (this is a problem for us since we are streaming)
It seems to me that when the transition to fast motion happens the encoder should simply generate an IDR frame. It looks like it is trying to follow the GOP size very strictly and only issues an IDR frame at the beginning of the next GOP. I'm using 150 for GOP size, GopRefDist of 1 and IdrInternval of 0; and I'm not setting the MFX_GOP_STRICT flag.
Any help would be appreciated.