[FFmpeg-devel] [PATCH 0/2] x86: hevc_mc: use proxy functions

Christophe Gisquet christophe.gisquet at gmail.com
Fri Oct 3 23:47:05 CEST 2014


2014-10-03 19:36 GMT+02:00 James Almer <jamrial at gmail.com>:
> When i first tried to tackle the libswresample asm to reduce the overall
> object size, the general reaction was that speed is more important than
> size.

Wasn't the trade-off much worse there? (the impact here is around 1%)

> Adding AVX2 MC functions is probably more attractive to users than having
> the library be a hundred or so kbs smaller.

Most probably, albeit I wonder how much it actually helps for MC. On
the other hand, who will be willing to try and fix things in that
code? The more I look at it, the more difficult it looks (to me).

Another example: the whimsical xmm reg usage declaration. Not a real
word bug, though.

> I'm all for smaller and cleaner source and object files, but if it makes
> it hard to add new instruction sets and at the same time brings a small
> performance hit, then I'm not sure it's worth it.

Yes, that's the trade-off I was more concerned with.

> Just my two cents. It's up to HEVC maintainers to decide that anyway.

I don't think the patch is acceptable either, but probably some time
in the future, this would better be addressed. I don't expect it to
happen, though.

Overall, there are much more important asm bits missing (idct, sao) anyway.


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