> From: Politis Archontis <archontis.poli...@aalto.fi> > Subject: Re: [Sursound] Enquiry on upmixing from 1st order ambisonics to 3rd > order ambisonics. > Date: 22 February 2019 18:15:00 GMT > To: Surround Sound discussion group <sursound@music.vt.edu> > > > Hi David, > > These upmixing methods extract a lot of information from the FOA recording > that is then re-used to essentially “synthesize" the HOA signals, with a > spatial resolution that would not be possible with the FOA recordings. They > are “active” in that sense, and signal-dependent, compared to the “passive" > classical ambisonic decoding. Their success depends of course on how > effective is their underlying model and how robustly they are implemented. > > In that sense there isn’t necessarily a large benefit in parametric upmixing > from FOA to 3rd-order, compared to parametric decoding for playback, since > these methods can also upmix directly from FOA to, say, 40 speakers or > headphones, with their maximum sharpness. However, the HOA upmixing could be > useful for people that are working with a HOA processing pipeline, and they > want to integrate FOA or lower-order material seamlessly. > > Regards, > Archontis Politis
Very few people have access to microphones beyond FOA, so that in a live recording a number of close microphones could be mixed in third order, with a FOA microphone as a "room" mic. For location recording, the FOA mic options are more robust, with better weather protection, and more practical than any higher order option. In a "synthesised" third order sound field, FOA recordings could be used as more "ambient" stems. The up-mix is a re-coder, FOA to third order. What would follow it is a third order mixer and a decoder to loudspeaker feeds. Other third order sounds could be mixed into the decoder. More than one FOA signal could be mixed into the re-coder. Whether it is better that each FOA signal has its own re-coder is debatable. If the re-coder includes its own identical decoder, which cannot be bypassed, the two (or more) sets of third order decoder loudspeaker outputs could be mixed together. The availability of an identical decoder, and a suitable mixer might be problematic. Ciao, Dave Hunt > From: David Pickett <d...@fugato.com> > Subject: Re: [Sursound] Enquiry on upmixing from 1st order ambisonics to 3rd > order ambisonics. > Date: 22 February 2019 17:45:28 GMT > To: Surround Sound discussion group <sursound@music.vt.edu> > > > At 02:37 22-02-19, Wilson Lim wrote: > >> ot sure if I have missed a discussion about upmixing with ambisonics on >> Sursound. >> >> Just wondering if anyone is willing to share some information on how to >> implement upmixing algorithms from 1st Order Ambisonics A&B-format to 3rd >> Order Ambisonics B-format. > > I am curious to know what advantage there is to playing back 1st order > upmixed to 3rd order. Doesnt it still sound like 1st order, since there no > information is actually added? Or are the images expectated to be more stable > on account of more loudspeakers being involved, on the analogy of stereo > played back through three loudpeakers? > > David > > From: Politis Archontis <archontis.poli...@aalto.fi> > Subject: Re: [Sursound] Enquiry on upmixing from 1st order ambisonics to 3rd > order ambisonics. > Date: 22 February 2019 18:15:00 GMT > To: Surround Sound discussion group <sursound@music.vt.edu> > > > Hi David, > > These upmixing methods extract a lot of information from the FOA recording > that is then re-used to essentially “synthesize" the HOA signals, with a > spatial resolution that would not be possible with the FOA recordings. They > are “active” in that sense, and signal-dependent, compared to the “passive" > classical ambisonic decoding. Their success depends of course on how > effective is their underlying model and how robustly they are implemented. > > In that sense there isn’t necessarily a large benefit in parametric upmixing > from FOA to 3rd-order, compared to parametric decoding for playback, since > these methods can also upmix directly from FOA to, say, 40 speakers or > headphones, with their maximum sharpness. However, the HOA upmixing could be > useful for people that are working with a HOA processing pipeline, and they > want to integrate FOA or lower-order material seamlessly. > > Regards, > Archontis Politis _______________________________________________ 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.
