[vorbis-dev] patents and separate entropy coding

Lourens Veen jsr at dds.nl
Fri Dec 15 10:17:32 PST 2000

Hi everyone,

first of all, I searched through the archives for any posts resembling
this, I didn't read all posts about the patents so if this has been
suggested before I apologise.

I read in an article on C|Net (I think, it was linked from Slashdot
anyway) that Thompson are threatening to sue you if Ogg Vorbis becomes a
success. Which is evil, and I'm also mad at them because they never
answered my mail (which was about how to get an mp3 patent license, of
all things). But I digress.

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
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

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
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.



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