[FFmpeg-devel] [PATCH] mpeg2: fix block_last_index when mismatch control modifies last coeff

Michael Niedermayer michaelni
Mon Jun 21 20:00:33 CEST 2010

On Mon, Jun 21, 2010 at 05:12:46PM +0100, M?ns Rullg?rd wrote:
> Michael Niedermayer <michaelni at gmx.at> writes:
> >> Having an incorrect value in block_last_index just seems wrong to me.
> >
> > i dont think a completely correct value would be very efficient speedwise
> > as 75% of the cases where the last coeff is set have no effect on the post
> > dct output for dc blocks (that is with an assumtation of dc values all being
> > equally likely)
> The last coeff is always manipulated, not only for dc-only blocks.  Do
> you know for sure exactly in which cases it makes a difference?

I dont think anything except the idct is using that coeff but i 
i cannot formally proof that it is so or is bug free ...
If you have doubts, its surely possible to perform some tests to see
if its value makes a difference outside the idcts


Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

I know you won't believe me, but the highest form of Human Excellence is
to question oneself and others. -- Socrates
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