[FFmpeg-devel] Broken DNxHD encoder and ASM optimizations activation

Michael Niedermayer michaelni at gmx.at
Thu Sep 20 22:42:34 CEST 2012

On Thu, Sep 20, 2012 at 06:42:17PM +0200, Matthieu Bouron wrote:
> Hello,
> The DNxHD encoder is broken in its current state with 8bit profiles.
> After some investigation, a regression was spotted at
> d211547dddf9deeb34b7dda9cd80b86f3f5cd07a revision with asm optimizations
> enabled or not.
> This commit moves some code, which enables some optimisations, from
> ff_MPV_commont_init_x86 to ff_MPV_encode_init_x86.
> ff_MPV_common_init_x86 is used by ff_dct_common_init. So the encoders which
> use ff_dct_common_init won't benefit anymore from the optimized
> quantization functions.

> It might be a good occasion to check if this kind of regression does not
> affect other encoders.

yes, i too think this would be quite important

> Also, the C version of the quantization function ff_dct_quantize_c (which
> is used for the DNxHD 8bit profiles) is broken and produces artefacts as in
> the following sample:
> http://samples.lolito.fr/DNXHD/test_dnxhd_120M_yuv422p.mxf

patch posted that fixes this, there are other ways to solve it but
this is the simplest

Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

If you think the mosad wants you dead since a long time then you are either
wrong or dead since a long time.
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