[Ffmpeg-devel] few remarks for h264 decoder

Gábor Kovács picard
Sat Dec 31 11:30:20 CET 2005


From: "Loren Merritt" <lorenm at u.washington.edu>
> I re-read pred_direct_motion(), and see
>    if(is_b8x8 && !IS_DIRECT(h->sub_mb_type[i8]))
>      continue;
> Are you sure there's a problem?

I didn't say pred_direct_motion will write into non direct subblocks.
But by filling the direct subblocks before the non direct subblocks, there
is a chance afterward for pred_motion() (actually fetch_diagonal_mv()) with 
non direct subblocks that think topright mv is available (pred_direct_motion filled it) 
when it shouldn't be.

> True, but that differs from the existing code only if:
> A pic is in both L0 and L1 (special case of the /*FIXME*/) or
> It's at a slice boundary and a pic is in L0 of one slice and L1 of the 
> other slice (special case of your point #6).

Sorry. I thought the /*FIXME*/ was about a pic being multiple times
in one(!) of the reference lists (example with weighted prediction, L0 could
have more occurences of a single pic with different weighted values).

bye, Picard

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