[Libav-user] Fast colourspace conversion on iOS

Nuno Santos nuno.santos at imaginando.pt
Sun Jul 18 19:01:21 EEST 2021


Thank you very much for this tip. Will try it out!

In fact I don’t need scaling. I really just need color conversion as the size of the frame never changes during the process.

Best regards,

Nuno

> On 18 Jul 2021, at 14:41, Yurii Monakov <monakov.y at gmail.com> wrote:
> 
> Hi,
> 
> You can try libyuv library to convert colorspaces. It is really faster than swscale from our tests.
> 
> Yurii
> 
> сб, 17 июля 2021 г. в 15:24, Nuno Santos <nuno.santos at imaginando.pt <mailto:nuno.santos at imaginando.pt>>:
> Nicolas,
> 
> Thanks for your reply.
> 
> The referred measures are based on:
> 
> - Intel i5 2.4 Ghz quad core (desktop)
> - 2018 iPad Pro 12’9 (A12X processor)
> 
> Regards,
> 
> Nuno
> 
> > On 17 Jul 2021, at 12:49, Nicolas George <george at nsup.org <mailto:george at nsup.org>> wrote:
> > 
> > Nuno Santos (12021-07-17):
> >> I’m using libav to mux a video file at full hd. 
> >> 
> >> At some point I need to convert the original frame at 1920x1080 RGB to YUV420P
> >> 
> >> This requires sws_scale to be called. On desktop it takes around 7/8 ms to convert a frame. On iOS it takes 28 ms.
> >> 
> >> I guess sws_scale is not optimised for iOS. How is people doing it on iOS then?
> > 
> > I do not think that sws_scale requires OS-specific optimizations.
> > 
> > What are the CPUs of your desktop and mobile devices?
> > 
> > Regards,
> > 
> > -- 
> >  Nicolas George
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