[FFmpeg-devel] [PATCH] bink: perform scan order permutation of quantization matrices in read_dct_coeffs()

[Peter Ross]

On Sat, Feb 19, 2011 at 07:29:06PM -0500, Ronald S. Bultje wrote:
> Hi,
> 
> On Sun, Feb 13, 2011 at 4:29 AM, Peter Ross <pross at xvid.org> wrote:
> > On Sun, Feb 13, 2011 at 07:41:32AM +0100, Kostya wrote:
> >> On Sun, Feb 13, 2011 at 02:32:58PM +1100, Peter Ross wrote:
> >> > This fixes visual glitches in Bink version 'b' files, as the quantization tables
> >> > were not being permutated.
> >> > ---
> >> > ?libavcodec/bink.c ? ? | ? ?4 +-
> >> > ?libavcodec/binkdata.h | ?618 ++++++++++++++++++++++++-------------------------
> >> > ?2 files changed, 303 insertions(+), 319 deletions(-)
> >> >
> >> > diff --git a/libavcodec/bink.c b/libavcodec/bink.c
> >> > index 928bf53..5ebf98c 100644
> >> > --- a/libavcodec/bink.c
> >> > +++ b/libavcodec/bink.c
> >> > @@ -678,8 +678,8 @@ static int read_dct_coeffs(GetBitContext *gb, DCTELEM block[64], const uint8_t *
> >> >
> >> > ? ? ?block[0] = (block[0] * quant[0]) >> 11;
> >> > ? ? ?for (i = 0; i < coef_count; i++) {
> >> > - ? ? ? ?int idx = coef_idx[i];
> >> > - ? ? ? ?block[scan[idx]] = (block[scan[idx]] * quant[idx]) >> 11;
> >> > + ? ? ? ?int idx = scan[coef_idx[i]];
> >> > + ? ? ? ?block[idx] = (block[idx] * quant[idx]) >> 11;
> >> > ? ? ?}
> >>
> >> 1) permutation depends on DCT type selected. Maybe in future Jason will
> >> fullfill his promise and write optimised DCT for Bink and it will require
> >> different permutation. Then decoder will be broken.
> >
> > True. My oops, the critical lines should therefore be:
> >
> > ? ? ? ?int idx = coef_idx[i];
> > ? ? ? ?block[scan[idx]] = (block[scan[idx]] * quant[bink_scan[idx]]) >> 11;
> >
> >> 2) you generate bink-b tables anyway so you can permutate them during creation
> >> unlike static data we have for latter Bink versions.
> >
> > Ok, for now. We'll need to revisit this when the Bink encoder is committed.
> 
> Will you send a new patch for this?

Already done! I send a alternative patch to this thread a week ago, Koysta quickly
approved, and Mans commited it.

-- Peter
(A907 E02F A6E5 0CD2 34CD 20D2 6760 79C5 AC40 DD6B)
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