When was the patent submitted? Regarding whether you can still use caching, if you can prove prior implementation of a product or concept in any given patent, then case law should allow you to use it without being in direct infringment of that patent.
This was to prevent a person patenting a known invention, and then suing existing users. Any body implementing that technology after the patent was applied for are likely to be in infringment. Steinberg VST could infringe this patent, but I would imagine they could prove prior implementation of audio caching algorithms that would prevent any suit from succeeding. Now, if you can find a peice of public domain dsp software that predates the patent and used audio caching, then you should be able to take that code and reuse it, or part of it. You avoid infringment since you are using a prior implementation under licence (GPL). SoX is a reasonable candidate, it has been around for yonks, but may not have audio caching SLab is another possibility, it does caching but is not so old (oops - that could put me in infringment). As long as your software does not violate the GPL then you are pretty much in the clear. Nick
