Talk:Range coding: Difference between revisions

Revision as of 05:57, 22 July 2006

Revision as of 17:23, 22 July 2006

Line 61:

:::--[[User:Simon G Best|Simon G Best]] 01:38, 22 July 2006 (UTC)

::::I think you misunderstand what I'm saying, especially about the patent issues. The [[term of patent]] in the U.S. is 20 years from the filing date of the application. (I'm also pretty sure that no country has a longer patent period than 20 years.) That means that nothing that was considered [[prior art]] in 1985 could be patented today. This includes range coding. It also includes many forms of [[arithmetic coding]] (see article). But because range coding is more specific than arithmetic coding, implementing range coding in its original form doesn't infringe patents. Implementing arithmetic coding in its original form doesn't infringe patents either, but the water's been muddied enough that people just fear using arithmetic coding; it's hard for a judge to tell what's frivolous and for an engineer to tell what's legal. I realize the same could be argued of range coding, but, as it is a more specific application, one can be more confident in the application not being patented. However, those that want to be really safe will go with Huffman codes and the like, avoiding anything invented after software patents were established. [[User:Calbaer|Calbaer]] 05:57, 22 July 2006 (UTC)

:::::On the patent issues, I think we more or less agree, at least with the following:-

:::::*Range encoding ''itself'' (as defined by Martin) is not patented. (It's been too long for any patents there might have been to still be in force.)

:::::*Arithmetic coding ''itself'' is not patented (anymore) (for the same reasons).

:::::*A number of more recent developments with arithmetic coding ''are'' patented. That's why it's said that arithmetic coding is (still) patent-encumbered.

:::::Have I understood this correctly? Are we actually in agreement on those points? (This still leaves the issue of whether or not arithmetic coding related patents apply to corresponding range encoders. But we can come back to that.)

:::::On the matter of whether or not arithmetic coding is range encoding, it seems we're not (yet) in agreement. Perhaps I've misunderstood what arithmetic coding is, but if, as you say, range encoding is "more specific" than arithmetic coding, then there must be at least one example of arithmetic coding (even if it's just theoretical) that isn't also range encoding. Could you refer me to one? I would find it enlightening :-)

:::::--[[User:Simon G Best|Simon G Best]] 17:23, 22 July 2006 (UTC)