On 12/18/2010 05:33 AM, Sampo Syreeni wrote: > On 2010-12-03, Ronald C.F. Antony wrote: > >> How would the IR reverb have to be "optimized" for ambisonics? >> Convolution is convolution is convolution, right? > > No, it ain't. Nobody does full 4x4 convolution; even the simplest case. > We optimize both using simple statistics, and the more powerful > psychoacoustics.
what guru fons does in the b-format reverbs that come with jconvolver is this: * measure a set of N 1x4 IRs from different positions into a b-format microphone at the desired listening spot (using sine sweeps) * truncate these after the early reflection phase * assume the late reverb is the same for all positions, so retain only one copy of that * provide a convolution matrix with N+1 inputs, consisting of all the positions plus one path for the late reverb. works very well. sampo, i was wondering: what do you mean by a 4x4 matrix? i have been dreaming of a b-format IR that will do the correct thing for any b-format input, but i couldn't quite get my head around how to do the measurement in real life... is that what you had in mind, too? it would be cool to have an anechoic b-format recording and then convolve it with a 4x4 room IR that will get stuff right... (in fact, i could use one right now, because the IR sets that i have lack a number of positions i'd need). -- Jörn Nettingsmeier Lortzingstr. 11, 45128 Essen, Tel. +49 177 7937487 Meister für Veranstaltungstechnik (Bühne/Studio), Elektrofachkraft Audio and event engineer - Ambisonic surround recordings http://stackingdwarves.net _______________________________________________ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
