I'm kind of under the impression that if the company that owns a patent isn't actively enforcing the patent (stating that you have to pay royalties/licensing fees/etc), then it's legally OK to use technology based on the patent.
Yet i think you are missing an issue: Are these patents valid worldwide? It would seem some countries will not accept patents from other countries, and some countries don't even accept to patent certain "things" at all.
I also have faith in MPC, and that last Phillips patent expiring soon. Maybe they are just waiting this (or it is SV8?) to release the encoder sources?
MPEG Layer 1 & 2 are infiltrated by 3 patents. - Efficient subband filter - Saving multiple samples with one common Scalefactor - Blockwise data processing 2) and 3) stand a good chance of failing either because of being "Prior Art" or lack of inventive ingenuity. I estimate the chance of that happening with 3) to be 100%. What remains is 1). Here I'd have to look again, if it [the patent] only covers the numerical implementation, or the exact filter design. If only the first is patented, a considerably slower equivalent could be written. That would hardly have an impact on the encoder (in which the subband splitter only accounts for < 3% and isn't even optimized the Klemm way), whereas it currently accounts for ca. 40% [of needed processing time] on the decoder side. If only the numerical implementation is patented, one could write a slower workaround for those who do not wish to use/pay for the non patented version. I would have to invest 2 days to work myself through the patent. On the other hand, the patent will expire in the next years. It was granted in 1986! The durations of patents are between 17 and 20 years.
Here are the latest page about patents which licencing should be handled by SISVEL, as saved by www.archive.org in Sep 28, 2001.PATENTS
My personal opinion is, that people here talk too eagerly about sueing, when discussing about MPC and patents, like if you use MPC, you are likely to be sued just like that. Rediculous!
Yeah, but it doesn't mean automatically sueing, like people here seem to eagerly assume. I'd guess that mp2 patent fees which apply to mpc decoder at this point aren't anything remarkable anymore.