[Ffmpeg-devel] Re: idct_mmi.c license in FFmpeg

Diego Biurrun diego
Tue Sep 5 15:48:33 CEST 2006

On Mon, Sep 04, 2006 at 06:44:04PM +0200, leon wrote:
> >I'm reviewing licensing in FFmpeg and stumbled over the file idct_mmi.c
> >that you contributed to FFmpeg way back in September 2002.
> >Unfortunately there is no clear license statement in the code.
> >The copyright header at the top of the file says
> >
> >/*
> >  Originally provided by Intel at AP-922
> >  http://developer.intel.com/vtune/cbts/strmsimd/922down.htm
> >  (See more app notes at 
> >  http://developer.intel.com/vtune/cbts/strmsimd/appnotes.htm)
> >  but in a limited edition.
> >
> >  column code adapted from peter gubanov
> >  Copyright (c) 2000-2001 Peter Gubanov <peter at elecard.net.ru>
> >  http://www.elecard.com/peter/idct.shtml
> >  Rounding trick Copyright (c) 2000 Michel Lespinasse <walken at zoy.org>
> >
> >  mmi port by leonvs at iae.nl
> >*/
> >
> >Are you the (sole) author of that code?  Can it be used under the LGPL?
> It's probably safe to say i'm the (sole) author of this particular 
> formulation of the idct algorithm in MMI instructions. The particular 
> formulation of the idct algorithm and the partial implementation in MMX 
> are (c) by intel (see ap-922)(to the degree that's even possible of 
> course), and Peter added the column code in MMX (afaik). Michel's 
> rounding trick actually is probably no longer used, but i couldn't find 
> what the trick exactly was at that time.
> For safety (IANAL) i just included the copyright statements of the 
> original mmx version in this mmi version.
> http://noomore.org/stuff/playstation2/psidct/idct8x8_xmm.html.txt
> If it's up to me, LGPL is fine.

Thanks, I've added a proper LGPL header to that file.


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