I have questions about UHJ decoding too. Richard, how did you get your decoding eqns?
My question is about http://en.wikipedia.org/wiki/Ambisonic_UHJ_format It has separate decoding eqns for 2 & 3 channel UHJ. They are consistent except for Y Y = 0.763*D + j*0.385*S 2-channel Y = 0.796*D - 0.676*T + j*0.187*S 3 channel It's been 30+ yrs since I pretended to unnerstan dis stuff but if IIRC, 3 channel decoding was supposed to be robust to the T channel. ie if the T channel faded out, decode would revert seamlessly to the 2 channel eqns. The idea was that the Velocity & "Energy" Vector directions would remain the same but T would increase the Vector Magnitudes. I thought I had this scribbled somewhere but all I can find is stuff for 45J which is UHJ's immediate predecessor and shows how long ago this was. I worked on the Calrec version of the Transcoder which was UHJ but I can't remember doing any UHJ work on the Calrec Ghetto Blasters which was Ken Farrar/Ellis's Periphonic System(s). I did their speaker matrix stuff though. And where do these eqns come from? I can't remember a formal document/published paper where MAG or Geoffrey Barton state the UHJ Encoding & Decoding Eqns. One coudl take the attitude that only Encoding needs to be specified and the user can do what he likes on Decode. Simple Matrix Inversion would give you a formal 3 channel Decode but that doesn't help me cos kunt kont or reed en rite .. 8>D Martin, when we resolve this issue, or even if we don't, we should put something in wikipedia stating the source or else something like "there is no formal source but we have this from Dr. Geoffrey Barton" or " we got these from reverse engineering the Audio & Design Trancoder & Decoder". I have been unsuccesful in my application to become a wiki editor cos kunt .... _______________________________________________ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
