Fons, I don't know how to compute the gain factors for 3rd order other than by numerical methods. I'm aware that Moreau published the gains of (1.000, .862, .612, and .305) but I don't know if those are correct or if there was a general solution published. I'm willing to give the computation a try, using my own crude methods (stylus and clay tablets), but I wouldn't be able to start realistically until after the AES Convention.
It's certainly an interesting problem! Have you got some 3rd-order 3D Ambisonic recordings to go with your Icosahedron? Eric ----- Original Message ---- From: "f...@kokkinizita.net" <f...@kokkinizita.net> To: Surround sound list <sursound@music.vt.edu> Sent: Tue, November 2, 2010 3:51:00 PM Subject: [Sursound] Help !! -- For AMB-decoding theory freaks only Hello all, For most of the day and evening I've been trying to find the error in some of the code I use to compute AMB decoders and which has been updated and extended recently. It fails on one of the test cases. If - I compute a systematic 3rd order decoder for a regular icosahedron, using the standard pseudo-inverse method, - apply the per-order rE gain factors which AFAIK are 1.0, 0.862, 0.612, 0.305, - then it should produce a uniform rE of 0.862. But it doesn't. I get a uniform rE of around 0.8 only if the 3rd order gain is decreased to something like 0.1 relative to the zero order one. The same test for 2nd order on a regular dodecahedron works perfectly, giving a uniform rE of 0.775. As does 3rd order horizontal on an octagon with rE = 0.924. I've gone through the code at least 10 times and can't find any error. Is there something wrong with my assumption that this should work ? TIA, Ciao, -- FA There are three of them, and Alleline. _______________________________________________ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound _______________________________________________ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
