(Sorry for the re-posting, sursound seems to destroy indentation from my mail manager, making the previous one hard to read..)
Hi Steven, There seems to be a misunderstanding, your seem to address the considerations raised by Stefan here on the list , not me :-) … I am quite a fun of the microphone and I have gotten excellent results rendering to large loudspeaker arrays (>25ch) using both ambisonic decoders and the parametric decoders that we are developing here in Aalto University. >On 22 Jun 2016, at 00:31, Steven Backer ><s...@mhacoustics.com<mailto:s...@mhacoustics.com>> wrote: >Nice work! It’s great someone is taking the time to put together the >infrastructure for web-based ambisonics. >I enjoyed watching your Intensity Analyzer. Thanks a lot! The intensity analyser it’s a bit incomplete at the moment, cause it’s showing the broadband intensity vector, so it’s hard to show multiple different sources from different directions. I’ll soon add a band-passed version. >How did you encode the raw Eigenmike signals? >Using some of our software (EigenUnits-Encoder or EigenStudio), or something >else? All the examples use the Encoder plugin provided by you. We have created our own encoding filters too here, based on dense anechoic measurements of the EM, which get some decent 4th-order components with a range of 2kHz~7kHz, but they lack some bass on orders 2&3 compared to your Encoder (I guess you’re using a thresholding approach at LF?) >In fact, we’ve found that some decoders, specifically for HOA, do present some >challenges that can degrade parts of the spatial image and spectral response. >There will be a paper presented on this topic at the upcoming AES Sound Field >Control conference in Guildford. This is an interesting point you raise cause ambisonic research itself has avoided it pretty much. I think because it breaks the useful separation between microphone encoding and loudspeaker decoding. Hence, decoding becomes frequency-dependent with respect to the array size, mics etc. We have used both an order-limited approach here (a n-th order decoding matrix per band that the EM delivers properly the n-th order signals), and a decoding filter matrix approach. But we have gotten good results one way or another so I know that EM can deliver :-). >In the past, we had control of both ends of the signal chain (i.e. the >beamforming in EigenStudio), and we could “do the right thing”. >Now without knowing a-priori what the decoder is doing it becomes more >difficult. This could explain some of the effects discussed earlier in this >thread. >We will soon be releasing some software updates that will hopefully address >some of these issues. So perhaps reserve some judgement for a later date ;-) That sounds great! (and no judgment from my side..) >>An Eigenmike has some aliasing limit frequency >You are correct that the Eigenbeams will spatially alias around ~8kHz. >We do implement a workaround for traditional beamforming, but for ambisonics >applications we just let it alias. >There is still usable signal up to (temporal) Nyquist and I’ve heard plenty of >material that sounds just fine up there. Let aliasing above that HF is reasonable. Another approach that may improve slightly compared to that, and something we have used in the past for parametric decoding, is to point your alias-suppression HF-beamformers towards the speakers. >>The eigenmike could be a nice tool for VR/AR recordings >Absolutely! We think so, too. >We’ve actually been pretty busy recently making quite a few recordings (some >with video!), and have some great material we are going to share publicly very >soon. Please do! The 3-4 recordings you have at the moment on the website do not do justice to the EM potential! Best regards, Archontis Politis -------------- next part -------------- An HTML attachment was scrubbed... URL: <https://mail.music.vt.edu/mailman/private/sursound/attachments/20160622/f94be3f4/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.
