> On Jul 23, 2018, at 1:16 PM, Nicolas George <geo...@nsup.org> wrote:
> 
> Jeff (2018-07-23):
>> It seems like libyuv has better performace on scaling than libswscale.
>> So I'm wondering is there anyone has tried integrating libyuv as a
>> scale filter before. I mean link it as a 3rd party lib, and then call
>> it's API through a wrap filter. Just like how libavcodec use libx264.
>> If not, why? Is there any licensee issue? Effort worth pay on it?
> 
> Finding out why it has better performance (figures?) and integrating the
> same optimizations would be more in line with the project policy, I
> think.
> 
> Regards,
> 
> -- 
>  Nicolas George

Hello,

I’ve used libyuv in a couple of projects in the past.  Nice little library and 
easy to bolt into an existing application when you need a quick scaling, 
colorspace conversion, or rotation in the most common YUV colorspaces found in 
decoders and graphics chipsets (e.g. stuff like NV12).  It also has pretty good 
optimized assembly for ARM for common use cases, making it perform well on such 
platforms.  Because it’s got a relatively simple API and build setup, it’s my 
“go to” library when my requirements are simple and I want to cross-compile for 
some embedded target.

That said, it takes a pretty simplistic approach to operations such as scaling 
and CSC, generally only providing a single scheme for each.  You can probably 
get comparable performance from libswscale if you adjust the tuning parameters 
to match whatever scaling algorithm libyuv internally implements.

As Nicolas suggested, if you have some specific use case you can describe where 
libyuv significant outperforms libswscale, it would be great to see some 
numbers and discuss.  It’s possible it has some optimized assembly worth 
looking closer at, but my gut reaction is that it’s likely just that 
libswscale’s defaults to a higher quality scaler (at the associated cost), and 
you can achieve comparable numbers as found in libyuv by tweaking the 
configuration.

Devin

---
Devin Heitmueller - LTN Global Communications
dheitmuel...@ltnglobal.com

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