2010/2/24 Jörn Nettingsmeier <[email protected]>: > hi alex, fons! > > On 02/23/2010 02:37 PM, alex stone wrote:
> > as fons said, jconv does a nice job of it, and i'm using it exclusively > now. i did my first experiments with farina's method, described here: > http://pcfarina.eng.unipr.it/Aurora/B-Format_to_UHJ.htm > it's essentially the same, only that farina provides one IR per > input/output pair, where fons does the same more elegantly with a single > hilbert transform (they do the 90° phase shift indicated by the "j" > coefficient as you find them on farina's page), and a couple of delays. I'm on the Hilbert as of last night. Makes a challenging job simpler, i'd agree. > > > if you want to do just the latter, and you already have a b-format, it's > easier to use the vmic plugin which is part of fons' AMB plugins - it > does the same job, but is simpler to use (no jack patching). > > if you have a b-format and want to produce stereo, these are the two > options you have: > > 1. use UHJ to fold it down automatically (including extra surround > information that allows the consumer to blow it up to horizontal > surround again, with a few compromises). but since uhj basically moves > the rear sound stage to the front, it can sound slightly over-ambient > (not as extreme as blumlein stereo, though). > > 2. use a virtual stereo mike to pick out a stereo perspective. it allows > for more control, is a lot easier to produce, and it's probably the > safer option if you want your mix to be reliable on consumer gear... 1.) I've had the ambient overdone already, so i understand what you're saying here. 2.) Virtual stereo mike? I don't understand this bit. Do we have one in Linux? Or are you referring to a process i have to build up myself? > >> The intent with this is provide ambisonic positioning, and convolver >> tail, right up until downsizing to stereo as the last part of the >> signal chain. > > i would definitely go that way, to be able to easily provide a b-format > output. Sounds like a plan. > > since you are dealing with artificial sources anyways, why stick to > first order? do your panning in higher order instead. the use of > resources is minimal (although it will create an insane amount of jack > ports, so use -P2048). it won't make any difference to your UHJ, since > it only ever sees WXY, but it would enable you to produce really crisp > n.1 or HOA decodes without any extra work. I don't know enough about higher order yet, but i am proficient in handling insane amounts of of ports, so that bit isn't overwhelming. :) > just one, totally unrelated, but smart(-ass) nonetheless: could you > please edit your replies to quote only the part you are directly > referring to? i'm usually very curious about things you have to say on > the list, but my mouse wheel finger is getting RSI... > > best, > > jörn > Good point, and i'll endeavour to do this in future. My thanks to you and Fons for the info, and your continued generosity in sharing. Alex. -- www.openoctave.org [email protected] [email protected] _______________________________________________ Linux-audio-dev mailing list [email protected] http://lists.linuxaudio.org/listinfo/linux-audio-dev
