[Ffmpeg-devel] moving non-SIMD parts of libswscale to LGPL

Luca Abeni lucabe72
Wed Nov 15 17:18:54 CET 2006


Hi Michel,

On Wed, 2006-11-15 at 16:25 +0100, Michel Bardiaux wrote:
[...]
> > Ok, the non-SIMD code is slower than
> > the SIMD-optimized one... But is it slower than the code currently used
> > by ffmpeg? I do not know, I never benchmarked them. I am putting this
> > benchmark task in my todo list (with a low priority).
> 
> Its on mine, too, but at least as far as on yours :-) But its going to 
> be hard to do (1) if the img_resample code is removed and the API 
> evolves in such a way that it becomes difficult to keep img_resample as 
> private code
I do not think you have to worry about this.
imgresample.c already contains code that permits to use img_convert()
and img_resample() through the swscale interface, when libswscale is not
linked. Just compile without --enable-swscaler, and use
sws_getContext(), sws_scale(), and friends...
(of course img_resample() and img_convert() are still available, but if
you switch your code to sws_* you do not need to modify it if/when you
decide to link the real libswscale)

>  (2) because of the if-0 which does not explain much.
I do not know what to say about this... I once noticed that
img_resample() is quite slow, and tried to really enable the mmx
optimizations contained in v_resample4_mmx() by removing the "&& 0", but
the output had a lot of green artifacts...
And I've not been able to fix the bug

> > Michel, I suspect you are over-reacting to something... 
> 
> You have to realize that if ffmpeg goes GPL (and by that I mean a 
> forking where most of the gurus follow the GPL branch and the LGPL 
> branch is left to wither and die) then for professional users, the 
> decision to use ffmpeg instead of some propretary codec software 
> becomes, retroactively, a very bad decision.
Maybe I am misunderstanding things, but I do not see such a "fork"
happening. There just are some developers that when adding new code
prefer to add it under the GPL license, and I do not think this is going
to impact professional users in a negative way (no working functionality
will be removed, or switched from LGPL to GPL)


				Luca
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