SQ Shadow Vector Soundfield Mapping

[stevendive]

My understanding of Ambisonics matches yours, it's a completely different approach and when it is working the speakers completely disappear as point sources. I have experienced this with several of OD's UHJ decodes on my system, it's impressive closing my eyes and realising I have lost any sense of where any speaker is. But the way it works with phase and filtering as Par4ken says makes me dubious it can be decoded with shadow vector. All OD did was extract the extra channel that is in the UHJ phase matrix, and then feed the 3 channels (UHJ is missing the height information of full 4 channel B format) into Bruce Wiggins software decoder that converts it to whatever speaker layout you specify, in this case 4.0.

If the decider isn’t an ambisonic one then it probably won’t *properly* extract a third, or any, channel. The effect might be interesting but incorrect. Ambisonics encodes direction, not loudspeaker feeds. In UHJ, specifically 2 channel BHJ, the fully extracted channels are W (omni pressure), X (front to back velocity) and Y (left to right velocity), from which the B-format decoder generates signals for the 4 or more horizontally placed ‘speakers. So the question is, why not just use a proper UHJ decoder (Eg. Bruce Wiggins Wigware or one of the used Meridian boxes)?

For anyone wanting to get into the maths, just do a search, “is my decoder ambisonic?”, and you will get a load of academic papers with plenty of detail.

 

[par4ken]

Because as ever with OD's decode processes, he's kept his UHJ decode process to himself and it will likely go to his grave with him. I have no ability to perform a decode myself.

Yes, but I thought that we both agreed that the Shadow Vector approach will not work with Ambisonics! There is not enough UHJ recorded material to really worry about it anyway!

I want to make the speakers disappear with RM, QS, and discrete.

Ambisonics has been applied to some discrete mixes AFAIK. The only thing is that those discrete mixes are designed for the typical speaker setup, you don't have the ability to set the decoder to match your own set up. Ambisonics is a bit like Atmos in that it can be setup for a differing number of speakers different placement and distance. With Ambisonics the idea of speaker channels is thrown out altogether.

 

[Mark Anderson]

Yes, but, There is not enough UHJ recorded material to really worry about it anyway!

A list of not enough UHJ recorded material for your viewing enjoyment. Ambisonic UHJ Discography

 

[Owen Smith]

Yes, but I thought that we both agreed that the Shadow Vector approach will not work with Ambisonics! There is not enough UHJ recorded material to really worry about it anyway!

If we're applying that metric, the only matrices that matter are DY, EV-4, SQ, QS and PL. And if one were being ruthless that could be shortened to SQ, QS and PL.

 

[par4ken]

A list of not enough UHJ recorded material for your viewing enjoyment. Ambisonic UHJ Discography

Kind of proves my point. Offhand the only thing listed there that really interests me is (maybe) "The Cowboy Junkies". I do have a copy of Alan Parsons "Stereotomy" which is great!

That being said I just bought an " NRDC - AMBISONIC SURROUND SOUND DECODER" off eBay. I've been looking on and off for years, one of the few decoders that I don't already own. Did I say that I love equipement? I already have a Troy automotive decoder but it doesn't have
settings for a larger room and different speaker layouts. So will give the NRDC a try on my main system, Today Ambisonics is usually/always done digitally, both encode and decode, so obviously I'm behind the times. So are you people, if you honestly worry about decoding UHJ!

 

[Owen Smith]

Kind of proves my point. Offhand the only thing listed there that really interests me is (maybe) "The Cowboy Junkies". I do have a copy of Alan Parsons "Stereotomy" which is great!

There are a lot of classical releases by Nimbus. Admittedly a drop in the ocean compared to other formats, but a classical fan has more UHJ choice.

 

[stevendive]

Kind of proves my point. Offhand the only thing listed there that really interests me is (maybe) "The Cowboy Junkies". I do have a copy of Alan Parsons "Stereotomy" which is great!

That being said I just bought an " NRDC - AMBISONIC SURROUND SOUND DECODER" off eBay. I've been looking on and off for years, one of the few decoders that I don't already own. Did I say that I love equipement? I already have a Troy automotive decoder but it doesn't have
settings for a larger room and different speaker layouts. So will give the NRDC a try on my main system, Today Ambisonics is usually/always done digitally, both encode and decode, so obviously I'm behind the times. So are you people, if you honestly worry about decoding UHJ!

On Bandcamp, there are a handful of one or two new-ish UHJ recordings and a few B-format ones.

Kind of proves my point. Offhand the only thing listed there that really interests me is (maybe) "The Cowboy Junkies". I do have a copy of Alan Parsons "Stereotomy" which is great!

That being said I just bought an " NRDC - AMBISONIC SURROUND SOUND DECODER" off eBay. I've been looking on and off for years, one of the few decoders that I don't already own. Did I say that I love equipement? I already have a Troy automotive decoder but it doesn't have
settings for a larger room and different speaker layouts. So will give the NRDC a try on my main system, Today Ambisonics is usually/always done digitally, both encode and decode, so obviously I'm behind the times. So are you people, if you honestly worry about decoding UHJ!

On Bandcamp, there are a few, more recent UHJ and B-Format pieces worth considering. Some are the usual ambient recordings that give the misleading impression this is all ambisonic is good for, but some give a much better idea of its abilities.

Tagging in Bandcamp for ambisonic material is pretty poor, though. You’ll find ambisonic material but listed along with a load of other non ambi stuff.

 

[Owen Smith]

On Bandcamp, there are a handful of one or two new-ish UHJ recordings and a few B-format ones.

If you've got B format all you need to do is pass it through Bruce Wiggins' software renderer configured for your speaker layout. There's no value in involving shadow vector in B format playback. The issue with UHJ is going from stereo matrix encoded to W, X and Y to feed into the ambisonic renderer.

 

[MidiMagic]

Yes, but I thought that we both agreed that the Shadow Vector approach will not work with Ambisonics! There is not enough UHJ recorded material to really worry about it anyway!

Ambisonics has been applied to some discrete mixes AFAIK. The only thing is that those discrete mixes are designed for the typical speaker setup, you don't have the ability to set the decoder to match your own set up. Ambisonics is a bit like Atmos in that it can be setup for a differing number of speakers different placement and distance. With Ambisonics the idea of speaker channels is thrown out altogether.

Actually, that can be done with full 360 degree RM. D4, DY, EV4, Scheiber, QS, DS, and PL are all variations of the same total encoding scheme with different speaker locations.

 

[MidiMagic]

If the decider isn’t an ambisonic one then it probably won’t *properly* extract a third, or any, channel. The effect might be interesting but incorrect. Ambisonics encodes direction, not loudspeaker feeds. In UHJ, specifically 2 channel BHJ, the fully extracted channels are W (omni pressure), X (front to back velocity) and Y (left to right velocity), from which the B-format decoder generates signals for the 4 or more horizontally placed ‘speakers. So the question is, why not just use a proper UHJ decoder (Eg. Bruce Wiggins Wigware or one of the used Meridian boxes)?

For anyone wanting to get into the maths, just do a search, “is my decoder ambisonic?”, and you will get a load of academic papers with plenty of detail.

Where do I buy a decider?

 

[stevendive]

If you've got B format all you need to do is pass it through Bruce Wiggins' software renderer configured for your speaker layout. There's no value in involving shadow vector in B format playback. The issue with UHJ is going from stereo matrix encoded to W, X and Y to feed into the ambisonic renderer.

The questions about using someone’s home brew UHJ decoder are, how incorrect is the implementation compared to Gerzon’s equations and what are the effects? At least with a ‘correct’ decoder, the correct shelf filters

Where do I buy a decider?

These days, it’s either a current Meridian unit or a *much* less costly used one, such as the 565 or 568.2 (least expensive, UHJ on analogue stereo input and possibly B-Format on optical) or the still fairly expensive G61 or G68 (UHJ on analogue and digital stereo in & both can process B-Format on their ‘MA1’ analogue LRC inputs). I have a G61.

 

[Mark Anderson]

Bruce Wiggins UHJ decoder software performs exactly as the Onkyo SV909 does decoding UHJ CD's and LP's. A true blessing.

 

[Owen Smith]

The questions about using someone’s home brew UHJ decoder are, how incorrect is the implementation compared to Gerzon’s equations and what are the effects? At least with a ‘correct’ decoder, the correct shelf filters

Bruce Wiggins and his software are well respected in the field of Ambisonics, I suggest you read up before trash talking him and it.

https://www.brucewiggins.co.uk/?page_id=78

 

[kfbkfb]

https://www.waves.com/ambisonics-explained-guide-for-sound-engineers^^^
...sixth-order Ambisonics with 49 channels.


Ambisonics seems popular for gaming/VR systems.

(maybe some posts here should be moved to an Ambisonics thread)


Kirk Bayne

 

[stevendive]

Bruce Wiggins and his software are well respected in the field of Ambisonics, I suggest you read up before trash talking him and it.

https://www.brucewiggins.co.uk/?page_id=78

Bruce Wiggins isn’t home brew. He implements Gerzon’s equations and I wasn’t suggesting anything else.

 

[Sonik Wiz]

i'm in London rather than Essex but i'm up for it!

So it's been about a month since your post on this. Very curious if you've had a chance to audition Malcolm's project?

 

[fredblue]

So it's been about a month since your post on this. Very curious if you've had a chance to audition Malcolm's project?

not yet, i've been away. i will write to Malcolm soon

 

[fizzywiggs41]

So, I'm curious as to where this new decoder project is at ?

Can we expect any news soon on its rollout ?

 

[malcolmlear]

Bravo.

How many bits?

24 bits, although like most 24 bit convertors the last 2 or 3 bits are down in the noise.

 

[malcolmlear]

Is that Pro Logic II Movie mode, with no Centre channel?

Personally I've had a fair amount of use of Pro Logic II Music mode on my previous AVR when listening to Proms concerts on BBC Radio 3. It's one of the things I've lost when I finally gave in and changed AVR.

Yes, the 4 channels work well together to produce a fairly solid center front image.