Binaural , Ambisonics , Q-Sound

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When NIMBUS produced about a dozen or so MLP DVD~A 4.0 discs some years back, those expecting discrete elements in the rears from these former UHJ Ambisonic masters might be a tad disappointed. They contained Ambience, only.

My Meridian 861 Pre~Pro has a built in Ambisonic decoder and all those NIMBUS UHJ RBCDs played through it contained ambient only surrounds!


R.2c574da03718b2164f93a6b18604d2a5

It’s not so much that only ambience was encoded on the rears, as all speaker signals in ambi contain information for the reconstruction of the horizontal 2D soundfield. Those discs had pre decoded UHJ speaker feeds (G-Format) in them, which were from performances where the ambisonic mic would have been facing the usually arrayed sound stage/orchestra at the front.

Sadly, Nimbus did not make the B-Format archives that would have made better G-Format releases. They often recorded straight to 2 channel UHJ. In principle, had full B-Format been used, primary sound sources could have been at any angle *and* been as well defined and spatially/tonally stable on playback as the front.

Nimbus still concentrates its attention on classical & world music, which is performed pretty much all with orchestra/ensemble at the front in great performance spaces. What goes on at the rear and sides of the soundscape will be then mainly reflections etc (ambience). Quadrophonists are used to thinking in terms of using rears as voices for sources whereas ambi is a full 2D or 3D sound scene description.
 
I am listening to the video on headphones and I am wondering , does a UHJ encoded ambisonic track require a UHJ decoder if it is listened to through headphones? If so was this program decoded through a decoder and then synced with the video in two channel stereo? The room they are in is very reverberant. Undoubtedly on purpose.

Actually, UHJ is close enough to QS that headphones should give a similar effect to that of QS through headphones.
 
I depends how you look at it. Both UHJ and QS are stereo compatible, so headphone playback should sound OK unprocessed.
Oh they're both stereo compatible and intended to sound OK by design. But I think saying they have a "similar effect" is going too far, unless by similar you mean not awful.
 
Oh they're both stereo compatible and intended to sound OK by design. But I think saying they have a "similar effect" is going too far, unless by similar you mean not awful.

The word ‘similar’ can be abused a bit. I know UHJ is both stereo and mono compatible by design (as given in its mathematics). Whether a particular performance sounds well in mono or stereo when folded down from UHJ is another matter, of course. I don’t listen much to quad in any form to comment upon.
 
No it is not, UHJ is a different matrix encoding and even decodes to a different number of channels.

I am not referring to the number of channels or the matrix parameters. Changes in these do not necessarily affect the encoding.

I am referring to the locus of the set of encodings of sounds from different directions into 2-channel stereo on the Poincare sphere.

No matter what decoding is used, these sounds are always encoded the same way

I always figure this locus when investigating any matrix.

The locus of encodings on the Poincare sphere for UHJ is close to the locus of encodings for QS.

This is how I know the following:

- There is no difference between the encodings of Dolby Stereo, Dolby Surround, Dolby Pro Logic, and Dolby Pro Logic II.

- There is very little difference between the encodings of any of the Dolby systems above and QS, Scheiber, EV-4, DQ, D-diamond, and QX.

All of these produce very similar sets of encodings of sounds from different directions.
So any decoder for any of them should be able to play them all.

And any of them can be decoded into any number of channels. I sometimes decode QS into 8 channels.

This is the Poincare sphere locus map for QS, Scheiber and D-diamond:
qsp-rm.gif


And this is the locus map for UHJ:
qsp-uj.gif


This is also why the single playback surround channel in Dolby Surround and Dolby Pro-Logic does not limit where sounds can be panned in the recording.
 
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What I’d really like to find is a VST plugin for a DAW like Reaper; I’m not really wanting to spend $5-600 for another used piece of gear. Do you know of any?
Bruce Wiggins officially released the file today on sursound

I've released a classic UHJ to square/rectangle decoder which can be found
at: Stereo to Ambisonics using UHJ

It can also pass out B-format with or without shelf filtering applied.

It's a JS effect, so Reaper is the ideal platform (there is a JSFX VST that should work on other DAWs, too). It implements both the shelf filters and forward preference controls as suggested in:
Gerzon, M.A., 1985. Ambisonics in multichannel broadcasting and video. *Journal of the Audio Engineering Society*, *33*(11), pp.859-871.

As an aside, looking through the old papers, it looks to me that the UHJ equations actually result in a W signal that's 3dB hotter than the SF mic standard (i.e. AmbiX gains!). Looking at the wireless world articles also suggests this (B format input to a unit that implements UHJ applied 3dB boost to W before decoding).
------------------------------------------------------------------------------------

Intall:
Create the folder Wigware following this path and copy all the files to it

C:\Users\YOU\AppData\Roaming\REAPER\Effects\WigWare\

Open Reaper and select the effect "UHJ Decoder/Transcoder

Then select the 4in/4out

1646435728946.png



and select these speaker outputs


1646435761037.png



You should be good to go
 
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