I have some first-order test files that you can try. They're FuMa order/normalization. There's "eight directions" and some pink noise pans. With a good decoder, localization should be pretty good with these -- better in the front than the back in my experience.
Aaron On Wed, Jul 5, 2017 at 5:53 PM, Aaron Heller <hel...@ai.sri.com> wrote: > Hi Martin, > > A few things... > > 1. You should use a first-order decoder to play first-order sources. > That's not the same as playing a first-order file into the first-order > inputs of a third-order decoder. > > 2. 1st-order periphonic (3D) ambisonics on a full 3D loudspeaker array > gets the energy correct, and hence the sense of envelopment; localization > is not that precise. The magnitude of the energy localization vector, rE, > in this situation is only sqrt(3)/3, which Gerzon noted is “perilously > close to being unsatisfactory." [1] > > 3. The decoders in the AmbiX plugins are single-band rE_max decoders, a > dual-band decoder will improve localization for central listeners a bit. > Both Ambdec and the FAUST decoders produced by the ADT (the ".dsp" files) > support 2-band decoding. > > 4. If you really want more precise localization, consider parametric > decoding using Harpex or the Harpex-based upmixer plugin from Blue Ripple > Sound. In my experience, it works very well with panned sources and > acoustic recordings in dry environments (outdoors, dry hall). For > recordings in very reverberant halls (like my recordings), the improvement > is not that great. > > Aaron (hel...@ai.sri.com) > Menlo Park, CA US > > > [1] Michael A. Gerzon. Practical Periphony: The Reproduction of > Full-Sphere Sound. Preprint 1571 > from the 65th Audio Engineering Society Convention, London, February 1980. > AES E-lib http://www.aes.org/e-lib/browse.cfm?elib=3794. > > 1. > > > On Wed, Jul 5, 2017 at 3:10 PM, Martin Dupras <martindup...@gmail.com> > wrote: > >> I've deployed a 21-speaker near spherical array a few days ago, which >> I think is working ok, but I'm having difficulty with playing back >> some first order A-format recordings on it. They sound really very >> diffuse and not very localised at all. I figured that some of you good >> people on here might have some idea of where I might be going wrong or >> what is not right. >> >> At the moment I'm using Reaper, and for decoding I'm using Matthias >> Kronlachner's Ambix decoder plug-in, with a configuration that I've >> calculated with Aaron Heller's Ambisonics Decoder Toolbox. I think the >> decoder configuration is right. I've calculated it with ambix ordering >> and scaling, and third order in H and V. The speaker array has six >> speakers at floor level (-22 degrees elevation), eight at ear level at >> 1m70 (0 degrees elevation), six at 45 degrees elevation and one at the >> apex. >> >> Now: if I pan monophonic sources using a panner (e.g. o3a panner, 3rd >> order), the localisation is pretty good. I've tested that with several >> people by panning to random places and asking to blindly point out to >> where they hear the source. Generally, they're in about the right >> place (say within 45 degrees on average.) >> >> On the other hand, if I play 1st order A-format recordings (mostly >> that I've made using our Core TetraMic), the localisation of sources >> is pretty poor. I also tried with the "xyz.wav" example file from Core >> (https://www.vvaudio.com/downloads) with the same results. To convert >> from A-format to B-format, I've tried using Core's VVtetraVST plugin >> with the calibration files for the mic (followed by the o3a FuMa to >> Ambix converter), and the Senneheiser Ambeo plugin (which does the >> same job, but in Ambix form already.) >> >> So what am I doing wrong? I've spent the last couple of days checking >> everything thoroughly. I've calibrated all the speakers to within 1dB >> SPL for the same signal received with an omni mic at the centre of the >> sphere. I've triple-checked that the encoder is in the right channel >> numbering: >> >> //------- decoder information ------- >> // decoder file = >> ../decoders/BSU_Array_6861_RAE1_3h3v_allrad_5200_rE_max_2_band.config >> // speaker array name = BSU_Array_6861_RAE1 >> // horizontal order = 3 >> // vertical order = 3 >> // coefficient order = acn >> // coefficient scale = SN3D >> // input scale = SN3D >> // mixed-order scheme = HV >> // input channel order: W Y Z X V T R S U Q O M K L N P >> // output speaker order: S01 S02 S03 S04 S05 S06 S07 S08 S09 S10 S11 >> S12 S13 S14 S15 S16 S17 S18 S19 S20 S21 >> >> I'll welcome any suggestion or advice! >> >> Thanks, >> >> - martin >> _______________________________________________ >> Sursound mailing list >> Sursound@music.vt.edu >> https://mail.music.vt.edu/mailman/listinfo/sursound - unsubscribe here, >> edit account or options, view archives and so on. >> > > -------------- next part -------------- An HTML attachment was scrubbed... URL: <https://mail.music.vt.edu/mailman/private/sursound/attachments/20170705/f8636dcd/attachment.html> _______________________________________________ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound - unsubscribe here, edit account or options, view archives and so on.
