Vorbis development, status & patent issues, PART 2 - Technical discussion Options

[Gabriel]

Moderator comment
Currently the Vorbis patent issue covers these threads:
Vorbis development, status & patent issues PART 1 - NON-technical discussion
Vorbis development, status & patent issues PART 2 - Technical discussion (This thread)
/Moderator comment

By looking at this:
http://www.xiph.org/archives/vorbis-dev/20...2/index.html#83
it seems that Xiph (at least in 2000) was open to the idea of disclosing the patent research.
Is this position changed now, or does it still stand?

[jmvalin]

Yes, Claim 4 is not easy to avoid. Claim 6 points back to Claim 2, where again the issue of changing signal amplitudes is mentioned.

Hmm, but Claim 4 points back to Claim 3, which points back to...etc,etc.

If presented with the vorbis code (and possibly an explanation of its operation) and a certain patent, I would find it very hard to make any judgement still, due to the language used in patent documents.

Actually, the way patents work is that to infringe on a patent, you need to infringe on *any* of the claims. However, to infringe on a claim, you have to do something that fits the *totality* of the claim. In this case, I would say that Vorbis doesn't infringe on claim 1, due to the "as a function of signal amplitude changes" (which probably needs to be there because there would likely be prior art for the general case). If Vorbis doesn't infringe on 1, then it automatically doesn't infringe on the others because all the others include 1.

Now, why would they bother making all the other claims dependent on 1 if the fact of not infringing on 1 prevents infringement on the others? The reason is that in probably think 1 may have prior art, in which case, the other claims are still valid (provided there's no prior art on them). Otherwise, prior art on 1 would have totally invalidated the patent. Anyway, the result is still that if Vorbis doesn't infringe on 1, it's safe from 5,214,742.