On 7/15/05, Michael K. Edwards <[EMAIL PROTECTED]> wrote: > Can you point me to a brief but technical summary of some of the Ogg > Vorbis codecs? I would be curious to compare them against the MP3 > techniques, about which I know at least a little bit.
I am _not_ trying to create trouble here; anything I can figure out in a couple hours of Googling is probably already on your (and your potential opponents') radar. If anything, this illustrates how difficult it can be to sustain work in this space without documenting the things you have done that you think are original in the form of patent applications, so you have something to bring to the table when it's time to negotiate an industry standard and form a patent pool. So I started by reading the Vorbis I spec, and it looks to me (on a very quick reading, IANAL, TINLA, little green men squeezed this through a pinhole in my tinfoil hat) like your decoder at least is clean WRT Fraunhofer -- at the risk of pushing the possibility of patent infringement onto the data stream itself. It's a bit like selling silicon which doesn't become patent-infringing until the firmware is loaded -- which is a perfectly good business strategy, followed by many silicon and board-level vendors in A/V space. Specifically, putting the codebooks in the header is clever, and I'm guessing that Floor 1 gets you out of the trouble that Floor 0 might have had any patent that specifies the Bark scale explicitly. There are always Lucent's patents to worry about (#5790759, #5285498, EP1160770, ... -- I can't believe they let this kind of crap through the system), and you might want to scan the rest of http://gauss.ffii.org/Search/All/IPC/G10L19/02 (maybe even all of bloody G10L19), but I'm probably teaching my grandmother to suck eggs. (If I were designing the codebook format, I might go for stratified trees with room for a heap index so that I could do stabbing queries and bulk insertion efficiently -- but that's really for streaming applications, and matters more when you have hardware on the back end that can only handle a minimal interlock during partial codebook updates. Agile codebook switching might also help compete with G.729E and modern equivalents. Xiph.org is welcome to reduce that idea to practice and patent it, doing whatever they like with the economic rights, as long as I am properly credited as co-inventor. :-) Note that K. Brandenburg, co-author of the 1992 paper you cite as the source of the MDCT, is almost certainly the same Karlheinz Brandenburg who filed #5040217 (assigned to AT&T Bell Labs, now presumably held by Lucent as well). A forward citation search for that patent number might be in order; you might particularly be interested in #6,704,705 (assigned to Nortel). By the way, where did you get the numbers in floor1_inverse_dB_table? If that's an important part of the psycho-acoustic magic, its provenance needs documenting, or it could get ugly in a court of fact when an "expert witness" lies with numbers. The general public can't tell what the significance of the difference between two exponential-ish curves may be, and you don't have the say-so of a patent examiner (for what that's worth) that your methodology does or doesn't differ in some way from the prior art as of date X. That's about all I can glean from the Vorbis I spec without long, tedious grinding through the patent databases, which I'm not qualified to do anyway. Now, is there any documentation about how the encoder works? How do you go about tracking whose chocolate gets into your peanut butter as people refine the encoding techniques? Cheers, - Michael (IANAL, TINLA, I know jack about patents except what I learned when filing one -- totally unrelated to audio -- with the help of a patent agent (now attorney) whom I respect a great deal.)
