[Ffmpeg-devel] (L)GPLed yuv2rgb code

[Michel Lespinasse]

On Fri, Dec 22, 2006 at 06:27:00PM -0800, Trent Piepho wrote:
> The code you linked to looks to be nearly identical to this code here:
> http://www.google.com/codesearch?hl=en&q=show:spitw_BsS18:XktR4Rb56GI:ZMtqWWQie4Y&sa=N&ct=rd&cs_p=http://libmpeg2.sourceforge.net/files/mpeg2dec-0.1.7.tar.gz&cs_f=mpeg2dec-0.1.7/libvo/yuv2rgb.c

Yes. I wrote this in 1998 or 1999, then sent it to aaron in april 2000
(just fished the email - I thought it had been earlier:) for integration
in his mpeg2dec. From then the code went to livid, then back into 'my'
mpeg2dec after aaron stopped maintaining it, and then into apparently
most everything else.

> It's from mpeg2dec-0.1.7 and claims copyright 1999-2000 Aaron Holtzman.  Of
> course that doesn't necessarily mean Aaron Holtzman wrote it.  I've found
> my code with someone else's copyright on it when they didn't write a single
> line.  But this does appear to be the oldest version of the code I could
> find, which is used all over the place.  I haven't found a version of
> mpeg2dec older than 0.1.7 to see just how "new" the "new yuv2rgb code"
> mentioned in the changelog for 0.1.7 really is.  Sometimes people think
> changing a variable name makes something new.

I dont know how to get every version out of SVN - plus, at the time
most things were just in aaron's private tree anyway, so we'd only see
0.1.5 then 0.1.6 then 0.1.7. But, at least 0.1.5 is accessible in SVN.
At the time the code was in display_x11.c and as you can see it was
quite different:
https://trac.videolan.org/libmpeg2/browser/tags/MPEG2DEC_0_1_5/mpeg2dec-livid/display_x11.c?rev=9

It would of course be possible for someone to write a LGPLed routine that
combines the Y,U,V values to generate an RGB pixel, but for this to be
LGPLed it should be implemented based on a mathematical description of
the operation to be performed rather than reuse the same particular
combination of tables and logical operations that were used in the GPL code.

PS for Luca: I know that there was no bad intent here and I'm sorry
I did not find out about this before you did the work.

Thanks,

-- 
Michel "Walken" Lespinasse
"Bill Gates is a monocle and a Persian cat away from being the villain
in a James Bond movie." -- Dennis Miller