[Mesa-dev] Naked DXTn support via ARB_texture_compression?

Joakim Sindholt bacn at zhasha.com
Sun Mar 20 13:56:55 PDT 2011

On Sun, 2011-03-20 at 21:31 +0100, Petr Sebor wrote:
> On 20.3.2011 20:23, Mathias Gottschlag wrote:
> >
> > Argh, meant to reply to list.
> >
> > If this nvidia library has a s3tc patent license, cannot this be used 
> > as a starting point, as done with the current dxt library? Unmodified, 
> > as an external binary? Wouldn't that circumvent the whole issue as you 
> > do not need a license for the hardware as it already has to be 
> > licensed if it was sold somewhere (well, at least on nvidia hardware, 
> > that is how I understand that FAQ entry, the part about narrow 
> > licenses does not seem to apply here), and you now suddenly have a 
> > licensed software encoder as well?
> >
> > Mathias
> I think this is a good point. And since nvidia texture tools is MIT 
> licensed, it could be very well packaged and become standard part
> of the distributions (At least Debian's DFSG rules are MIT compatible, 
> haven't checked other distros).
> I'd say - great idea, but then, we'll have to believe we actually can 
> use such data on the hardware that sure has to be licensed as well.
> I believe it is clear. The compression and decompression algorithms are 
> both implemented in packages that got to be covered by
> a license.
> Petr

People smarter than me, please comment on this.
The specific text of the nvidia-texture-tools FAQ is:

NVIDIA has a license of the S3TC patent that covers all our products,
including our Texture Tools. You don't have to obtain a license of the
S3TC patent to use any of NVIDIA's products, but certain uses of NVIDIA
Texture Tools source code cannot be considered NVIDIA products anymore.
Keep in mind that the NVIDIA Texture Tools are licensed under the MIT
license and thus are provided without warranty of any kind.

Furthermore, the author of the package has this to say in the comments:

Comment by project member cast... at gmail.com, Mar 14, 2009:
That's open to interpretation. My understanding is that you can use the
tools/libraries 'as is' in your application. However, if you pick the
files that implement the patent and integrate them in your product, then
that cannot be considered a use of the NVIDIA Texture Tools product
anymore. Feel free to contact us if you want more clarification.

Now what I see is that the package exports a static library called
libnvtt.a which does in fact export DXT compression and block
decompression at a first glance. Can this be used in mesa?

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