[FFmpeg-devel] Cleanup libswscale and reimplement GPL code under LGPL

Luca Abeni lucabe72
Mon Apr 7 16:59:01 CEST 2008

Hi Ramiro,

Ramiro Polla wrote:
>> IMO rewriting the SIMD code because of GPL makes no sense, why would you
>> want to do that? The code can be used without SIMD, is it so bad that
>> non free software will be a little slower?
>> Also i will not review any rewritten SIMD code.
> Ok, but what about the rest of the project? Instead of rewriting SIMD
> code, cleanly #ifdef'ing it so that swscaler can be the default scaler,

I think the SIMD code is already #ifdef'ed (I do not know if it is
cleanly #ifdef'ed or not, this depends on how you define "cleanly" :).
Compiling only the non-SIMD code is quite easy.

The problem is that the non-SIMD code (which is mainly LGPLed) depends
on some conversion tables which are generated by GPLed code. So,
libswscale depends on "--enable-gpl". To make the LGPLed code really
useful without "--enable-gpl", you have to re-implement the lookup tables
generator and release it under LGPL.
I think Michael agrees that re-implementing the tables generator makes
sense (and I apologize if I misunderstood this).


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