Checkout the AES papers at www.ambiophonics.org. But basically if you have a front pair that was recorded with accurate values of ITD and ILD and a rear pair isolated from the front that also has accurate ITD and ILD then you can have a full circles of very realistic sound in the horizontal plane using RACE, BACCH or similar crosstalk cancellation apps with just four speakers. You use one pair in front less than 20 degrees apart and one to the rear at a similar angle. This insures that you can have a lots of listeners along the center line. SQ or 4.0 SACDs sound fantastic this this way and the system is relatively non critical as to angles and speaker positions. Loudspeaker binaural (4 speaker type) is also a lot more pinna friendly since the speakers are central/frontal for dialog soloists, etc. If you make 4.0 recordings using an Ambiophone then the front and back pairs are isolated and proper ITD and ILD values are preserved and available to be deliver intact as described above.
Anyone in the NYC area is welcome to hear this in person. Height ambience is also provided for classical music but that is another topic and one can also provide envelopment and a rear concert hall ambience for older 2.0 sources like LPs. Incidentally, in my experience off side Ambiophonics sounds a lot better than off position Ambisonics probably because both left and right channels are being outputted by both speakers or if one is close to a side speaker one hears good mono. Regards, Ralph Glasgal -----Original Message----- From: Sursound [mailto:[email protected]] On Behalf Of Dave Hunt Sent: Friday, March 05, 2021 6:44 AM To: [email protected] Subject: Re: [Sursound] binaural to FOA? Hi Marc, Yes, this is very difficult to do properly but a simple bodge is surprisingly effective. Undoing the built in binaural encoding from the original recording is next to impossible. I have done what is suggested in the ambisonic.net sources in Max. XY or polar coordinates place the left and right channels at variable points on a circle in a 1st order ambisonic encoder, giving a basic B-format output. This image can then be rotated by fairly simple maths to alter the coordinates of both channels together, or by rotating the B-format signal. The rest is done by an ambisonic decoder. Once in B-format, the WXY components can be manipulated; gain, eq, directional dominance. You can also apply a Z coordinate to move the image up and down. The result is undeniably diffuse, but usable. Generally binaural recordings sound OK as normal stereo, obviously without the proper spatial impression. Interesting effects are also achieved by treating stereo as UHJ and deriving B-Format from that. I think there is something on that on ambisonic.net, as well as super stereo and Dolby stereo. Transaural crosstalk cancellation only works over a very small area, and becomes more complex for quad. Many such systems go for some form of closely spaced dipole speaker layout, possibly with extra speakers. The University of Southampton had something like that, but references might take some finding. Ciao, Dave Hunt > On 4 Mar 2021, at 17:00, [email protected] wrote: > > From: Marc Lavallée <[email protected]> > Subject: [Sursound] binaural to FOA? > Date: 4 March 2021 at 13:55:42 GMT > To: Surround Sound discussion group <[email protected]> > > > I have a "back to the basics" question. > > For a simple project I planned to record in FOA or HOA, but the final render > would be in simple quad (horizontal). So I don't need a lot of resolution. I > enjoy recording with binaural microphones (the kind that looks like cheap > earbuds), so I can record continuously without being noticed. > > So I wondered; is there a method to "convert" binaural to horizontal-only > FOA? Apparently there is: > > https://www.ambisonic.net/quaduhj.html > > http://www.ambisonic.net/ambimix.html > > I guess my question is: what would be the software equivalent of a pan-rotate > device? > > Marc _______________________________________________ Sursound mailing list [email protected] https://mail.music.vt.edu/mailman/listinfo/sursound - unsubscribe here, edit account or options, view archives and so on. _______________________________________________ Sursound mailing list [email protected] https://mail.music.vt.edu/mailman/listinfo/sursound - unsubscribe here, edit account or options, view archives and so on.
