On 04/04/2013 05:41 AM, Alexander E. Patrakov wrote: > 2013/4/3 Tanu Kaskinen <tanuk at iki.fi>: >> On Wed, 2013-04-03 at 10:20 +0100, Carl Gridley wrote: >>> Wow, wasn't expecting code so quickly - thanks! >>> >>> >>> I've been away for a bit. Is this working and done? Do I need to get >>> PA 3 and a patch on my system or is it all good and in the queue for >>> an offical release in the future? >> >> You need to apply the patch yourself, because my solution was not >> considered good. It seems that this was only discussed in IRC, not on >> the mailing list. A bug report has been filed, which contains the >> explanation why the solution was not accepted: >> https://bugs.freedesktop.org/show_bug.cgi?id=62588 > > I'd say that the "no should mean no" argument is at least incomplete, > in the sense "more discussion is needed". First, did the opponents > present a use case when a pure "no" (with all associated side effects) > would yield the correct result for all use cases? I think the primary objection was not that there was a use case or need for the mono-upmix-only option. The objection was mostly that having a "enable-remixing = no" option that actually did remixing would be quite confusing. > Second (semi-trolling, don't take too seriously) remixing by channel > copying and linear summation is so old-school! No modern 5.1 receiver > does it by default when fed a stereo signal over SPDIF or HDMI. They > have a US-patented upmixing algorithm from Dolby inside, using Z > transformers and even non-linear elements, and most so-called "stereo" > records are produced with that "matrix decoder" in mind. So, once this > fancy upmixer is completely reverse-engineered, it should be an option > at least in the countries where the patent is invalid. And yes, this > does mean that the "enable-remixing" option is a misnomer, as it is > not a boolean. The first match on Google on the topic yielded this result: http://www.sersc.org/journals/IJSIP/vol2_no4/7.pdf It looks like the first option, "Passive Surround Decoding" yielded pretty good listening results and seems not too difficult to implement. The other steps - time delay, low-pass filter, phase shifter - also needs somebody to implement them though. Also; I guess in some cases distributions and others have been reselling patent licenses, so even in patent-covered countries there might be a possibility to use such an algorithm. -- David Henningsson, Canonical Ltd. https://launchpad.net/~diwic
