On Tue, Jun 20, 2017 at 08:18:20PM -0400, Ronald S. Bultje wrote:
> Hi,
>
> On Tue, Jun 20, 2017 at 5:22 PM, Michael Niedermayer <mich...@niedermayer.cc
> > wrote:
>
> > On Tue, Jun 20, 2017 at 08:47:33AM -0400, Ronald S. Bultje wrote:
> > > This allows using non-simple (e.g. simplemmx) IDCT implementations.
> > > The result is not bitexact (which is why the fate test continues to
> > > use -idct simple), but the PSNR between C/MMX goes from ~35 to ~90.
> > > ---
> > > libavcodec/mdec.c | 14 ++++++++++----
> > > 1 file changed, 10 insertions(+), 4 deletions(-)
> > >
> > [...]
> >
> > > @@ -212,9 +213,7 @@ static int decode_frame(AVCodecContext *avctx,
> > > static av_cold int decode_init(AVCodecContext *avctx)
> > > {
> > > MDECContext * const a = avctx->priv_data;
> > > -
> > > - if (avctx->idct_algo == FF_IDCT_AUTO)
> > > - avctx->idct_algo = FF_IDCT_SIMPLE;
> >
> > iam not sure this should be in this patch
>
>
> Can you be more precise?
> Would you like this in a separate patch?
yes
> Or do you
> think it's wrong?
no, i dont think the change is wrong, but thats just thinking
The code was added in:
commit e3e3c82555e2382125195c1ba9f34b5a43299abc
Author: Vitor Sessak <vitor1...@gmail.com>
Date: Sun Jan 2 11:16:21 2011 +0000
Make PSX MDEC decoder output YUVJ420 and always use IDCT_SIMPLE. This
makes the output much closer to original Playstation hardware.
>
> I believe this code was there because the PSNR between FF_IDCT_SIMPLE and
> SIMPLEMMX was 35, which is pretty terrible. This was probably because of
> the bug in the dequant permutation that's fixed in this patch. After this
> patch, the PSNR between the two is 90, which is pretty decent and good
> enough for me to enable it by default (although not in fate).
>
> Ronald
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Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
"I am not trying to be anyone's saviour, I'm trying to think about the
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