On Thu, Mar 04, 2021 at 02:15:12PM +0000, Augustine Leudar wrote: > http://www.ambisonic.net/ambimix.html
Or 'how to do FOA on a stereo mixer' 38 years ago... Amusing but pretty irrelevant today. Some simple facts: Horizontal FOA requires three _independent_ signals, W, X, Y. Binaural only provides two. That means that a correct linear transformation from binaural to FOA can not exist. That's just maths you can't argue with. It could be done using 'parametric' methods, which means you try to mimic how a human brain analyses the information it gets from the ears, and uses it to reconstruct a scene. That involves 'sensor fusing', i.e. information from other sources (e.g. visual), expectations, previous experience of 'known sounds', and even cultural bias. Maybe possible with AI in ten years but certainly not today. A human also can and will rotate his/her head in order to resolve ambiguous localisation. This can't be done given only prerecorded binaural signals, so part of the required info will be missing anyhow. That said, not all is lost. Conversion from binaural to stereo is possible using something similar to <http://kokkinizita.linuxaudio.org/linuxaudio/zita-bls1-doc/quickguide.html> This is a linear process and it could be done using convolution as well. But then you don't have the interactive controls and that could be a problem in practice. Given the stereo signals, you could you use a simple upmixing process to separate direct and diffuse sound. Finally, using convential AMB methods, pan the direct sound to the front and the diffuse part to the back. That should give you 'plausible' rendering of the original binaural recording, assuming the person wearing the in-ear mics didn't move his/her head randomly too much. Ciao, -- FA _______________________________________________ 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.
