[vorbis-dev] patents and separate entropy coding
segher at wanadoo.nl
Fri Dec 15 18:59:52 PST 2000
> Thing is, I understand that they have a patent on compressing audio by
> transforming to the frequency domain, quantising, and then entropy
> encoding, which is what Ogg Vorbis does, so there's trouble. Now, I've
Vorbis uses a vector quantizer. A vector quantizer is _not_ the same
as first quantizing, and then entropy encoding. Part of the entropy
encoding is already included in the quantizer, and they are not
separable. So this patent won't work.
> been working on a Haar wavelet image compressor, and since I haven't
> written the entropy coder yet I just dump my quantised output to a new
> file. This file is as large as the original file. Then I simply use
> gzip, which compresses well because of the preprocessing.
> So, should trouble arise, you could make Ogg Vorbis from a compressor
> into a transformer. Since you're not doing any entropy encoding, in fact
> you're not even compressing anything, they won't have anything against
Problem is, any application that uses Vorbis, _will_ have to license the
patent. Otherwise, Vorbis would be clean trivially, as most patents
talk about "storing a file" or "transmitting a signal", which libvorbis
does not. But Vorbis has problems with patents that prevent applications
from using Vorbis as well as with patents which threaten Vorbis itself,
as Vorbis is meant to provide license/patent/claim-free natural audio
> There may be a problem with this, which is that it may in fact then be
> illegal to create .ogg.gz files without a license from them, but it
Read the patents (very carefully) please; this doesn't apply. Oh,
and if you first create an .ogg file, and than an .ogg.gz file, it
won't apply anyway, as some user action is required (patent says: a
device which does... etc.)
> would be pretty hard for them to hold that since they don't have any
> patents on transforming audio data or on entropy encoding random data,
> just the combination.
> Well, IANAL, but I thought that it might be useful.
At least you were thinking; most people complaining about patent
stuff ain't. Most of those people are just reiterating (with
some mistakes) what they read on some news-site (which had obvious
errors to begin with). But no hard feelings to anyone, of course.
just getting tired of reading false statements over and over again.
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