[Ffmpeg-devel] Optimised yuvj420p_to_rgba32

[Luca Abeni]

Hi Michel,

On Wed, 2006-03-22 at 19:30 +0100, Michel Bardiaux wrote:
> I succeeded in decoding from my application a simple JPEG file using 
> lavc (details on request). Its 40% faster than using the generic libjpeg 
> (IJPEG6b), which is great. But -pg profiles show that 40% of the time is 
> spent not in decoding the image, but in converting to B/G/R/X which is 
> mandated by the rest of my application since the image has to be sent to 
> an X server on Ix86/Linux.
I saw similar results in the past: it seems that ffmpeg codecs are much
more optimized than the ffmpeg code doing rescaling / color space
conversion.

> Is there a hope of SSE-fying that function? I mean, I dont ask that 
> anyone do it, just that someone expert in MMX and SSE tells me if it is 
> *doable* (and worth it).
Try to use swscaler with the patches I posted some time ago...
I did not test the jpeg colorspace, but some tests converting rescaling
and converting between common colorspaces showed that you get a very
good speed improvement.
(so, it is certainly doable :)


			Luca
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