[FFmpeg-devel] [PATCH] avcodec: use looking up crop table method when do clip

[Michael Niedermayer]

On Mon, Aug 10, 2015 at 08:05:37PM -0400, Ronald S. Bultje wrote:
> Hi,
> 
> On Fri, Aug 7, 2015 at 5:30 AM, 周晓勇 <zhouxiaoyong at loongson.cn> wrote:
> 
> > based on last h264qpel optimization patch i have pushed
> > do i need separate this patch to double? cause one file to change loongson
> > arch
> > use looking up crop table method may boost up decode on loongson, and with
> > this patch x86 pass fate too
> > but i have not tested on other arch
> >
> >
> > test on loongson-3b
> > time ./ffmepg -i 1280x720.mp4 -f rawvideo -an -vframes 4096 -y /dev/null
> >
> >
> > no patch:
> >
> >
> > real 0m58.2s
> > user 4m59.1s
> > sys 0m5.8s
> >
> >
> > with patch:
> >
> >
> > real 0m53.9s
> > user 4m33.2s
> > sys 0m6.2s
> >
> >
> > ---
> > From 68e88b17d113875d829a9936284d3551fd499139 Mon Sep 17 00:00:00 2001
> > From: ZhouXiaoyong <zhouxiaoyong at loongson.cn>
> > Date: Fri, 7 Aug 2015 16:33:10 +0800
> > Subject: [PATCH] avcodec: use looking up crop table method when do clip
> >
> >
> > Signed-off-by: ZhouXiaoyong <zhouxiaoyong at loongson.cn>
> > ---
> >  libavcodec/bit_depth_template.c | 4 ++--
> >  libavcodec/mips/h264qpel_mmi.c  | 4 ++++
> >  2 files changed, 6 insertions(+), 2 deletions(-)
> >
> >
> > diff --git a/libavcodec/bit_depth_template.c
> > b/libavcodec/bit_depth_template.c
> > index 8018489..759cd30 100644
> > --- a/libavcodec/bit_depth_template.c
> > +++ b/libavcodec/bit_depth_template.c
> > @@ -72,7 +72,7 @@
> >  #   define pixel4 uint32_t
> >  #   define dctcoef int16_t
> >
> > -#   define INIT_CLIP
> > +#   define INIT_CLIP const uint8_t *cm = ff_crop_tab + MAX_NEG_CROP;
> >  #   define no_rnd_avg_pixel4 no_rnd_avg32
> >  #   define    rnd_avg_pixel4    rnd_avg32
> >  #   define AV_RN2P  AV_RN16
> 
> 
> I remember vaguely that we had something like this before, but we removed
> it because on some systems, fuzzed bitstreams could trigger out-of-array
> reads. Or am I making that up? See 263bb6edcf6b767006fcde315850d3a60b3fceed

right, i forgot about that 


[...]
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Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Democracy is the form of government in which you can choose your dictator
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