[FFmpeg-devel] [PATCH 5/6] x86/hevcdsp: add ff_hevc_sao_edge_filter_8_{ssse3, avx2}

Christophe Gisquet christophe.gisquet at gmail.com
Wed Feb 4 21:26:36 CET 2015


2015-02-04 21:14 GMT+01:00 James Almer <jamrial at gmail.com>:
> On 04/02/15 9:39 AM, Christophe Gisquet wrote:
>> Are the first number for each case from before you split out the
>> restore part? Otherwise, that's gruesome.
> The benchmarks were done with every patch up to this one applied, so yes, after the
> split. The file i used to bench went from ~36fps to ~46fps after this patch.
> The C version must be pretty inefficient (That CMP macro inside the loop probably
> creates lots of branches). Or maybe GCC was dumb.

At this point this whole function spends more time copying data than in the dsp!

> Ah, good to know it's constant now. Although until we add x86_32 versions of these
> functions it doesn't really bring any real benefit.
> I'll update the prototype and assembly anyway.

It was a bit arbitrary, and expecting you would need that change.
Anything lower would break avx2 reads.

> For that matter, do .asm files have access to FF_INPUT_BUFFER_PADDING_SIZE?

Unfortunately no, for instance, I added an equivalent MAX_PB_SIZE to
hevc_mc.asm, but this later one is pretty strongly set in stone.

> if at
> some point we change its value (For example, once AVX512 code starts being
> committed), then srcstride will be something else.
> Probably not a problem since whenever that constant is updated in avcodec.h it
> can also be updated in hevc_sao.asm, but it would be nice not having to bother
> doing that.

It would need to go through config.asm I bet, but agreed, this may
break. Unfortunately nothing automagical yet, but that's probably not
the only code fragile to this.


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