[Theora] Independent implementations?

[Ralph Giles]

On Mon, Jul 12, 2004 at 09:52:30AM +0900, Kyungjoon Lee wrote:

> When people ask me what Vorbis's license terms are, I usually tell
> them that the bitstream format is in the public domain, that the
> reference libraries are licensed under a BSD-like license, and that
> the example programs are licensed under the GNU GPL. (Note the
> distinction between filespec and implementation here.)

Yep. Or close enough. The 'format is in the public domain' is something
of a shorthand.

> So my question is, is it alright to create and distribute a Theora
> codec which isn't based on the Theora code from Xiph.org? If VP3 code
> is in Theora, and VP3 is patented, does that mean that you can't
> write/modify a non-Xiph Theora codec without infringing on On2's
> patents?

The operative grant here is included in the vp32 package as it was
donated to xiph.org, which postdates the releases from vp3.com that
folks have been referring to. To wit:

- In addition, On2 Technologies, Inc. makes the following statement
regarding technology used in this software:

On2 represents and warrants that it shall not assert any rights
relating to infringement of On2's registered patents, nor initiate
any litigation asserting such rights, against any person who, or
entity which utilizes the On2 VP3 Codec Software, including any
use, distribution, and sale of said Software; which make changes,
modifications, and improvements in said Software; and to use,
distribute, and sell said changes as well as applications for other
fields of use.

(http://svn.xiph.org/trunk/vp32/LICENSE)

You have a good point about independent implementations; it would have
been nice if we'd gotten a clearer statement that they were included.
However I think you're fine. The intent was clearly that the technology
is freely licensed for us in the context of VP3-based video codecs, which
an implementation of the Theora bitstream specification clearly is. One
also has an out in the final phrase, which would seem to grant license
of the technology in general.

Of course, most legal systems construct patents in such a way that
reasonable certainty is impossible, I think one is as safe here as
one can generally be. Please do continue with your independent
implementation; such things are very important for the health of the
format.

I've included the above txt in a file called LICENSE in the theora
source as well; hopefully this is prevent this confusion in the
future.

Cheers,
-r