Fons... I assume what your doing is making a decoder with shelf gains given by Moreau and Daniel and then testing it numerically and not getting the expected value of rE. I have code to do that as well and will take a look it it after the AES Convention this weekend.
Aaron On Wed, Nov 3, 2010 at 10:16 AM, Aaron Heller <[email protected]> wrote: > On Tue, Nov 2, 2010 at 5:12 PM, <[email protected]> wrote: >> On Tue, Nov 02, 2010 at 04:07:40PM -0700, Eric Benjamin wrote: >> >>> 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. >> >> The gain factors provided by Daniel (and Moreau) are a general solution. >> For 3D, rE it involves Legendre functions: >> >> rE = largest root of P_{M+1} >> g(m) = P_m(rE) >> which also means g(1) = rE > > A while back I posted some Maxima code to do this > > http://www.ai.sri.com/ajh/ambisonics/shelf-gains-example.html > > For third order, I get 0.861, 0.612, 0.305 > > which is the same as you and Eric get. > > However, I have to say that I've never seen the derivation of this > result. Moreau gives it in Table 3.5 of his thesis without > derivation, citing Daniel's thesis. Page 183 of Daniel's thesis cites > Appendix A.4.3 in his 1998 AES paper "Ambisonic Encoding of Other > Audio Formats...", which does not appear to have an Appendix 4.3. > > Aaron <[email protected]> > Menlo Park, CA US > > Aaron > _______________________________________________ Sursound mailing list [email protected] https://mail.music.vt.edu/mailman/listinfo/sursound
