Discussion:
Going from 3rd order to 1st order.
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James Anthony Enda Bates
2017-02-07 19:54:42 UTC
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Hi everyone,
so it seems to be very common practice now to convert from 3rd order to
1st order by simply using the first 4 channels of the 3rd order stream.
However, I have this very vague recollection of that not being quite right
and that there are some differences between the WXYZ channels in different
orders? But I cant seem to pinpoint the reference or source for that, so
perhaps my memory is just wrong?
Any one have any ideas on this? Could this be an issue with Furse-Malham,
rather than Ambi-X, or am I just completely wrong about that?

It's quite a relevant question as you often need to prepare both 1st and
3rd order mixes these days for 360 videos.
Thanks all,
enda




--

Dr. Enda Bates
Teaching / Research Fellow
Music & Media Technologies / School of Engineering
Stack B, IFSC, Dublin 1, Ireland.

+353 1 896 1434
***@tcd.ie
www.endabates.net <http://www.endabates.net>www.tcd.ie
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Peter Lennox
2017-02-07 21:13:48 UTC
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Enda - ask Bruce - I've had this same conversation with him. I have to admit, as a cheap and cheerful quick fix, I often simply use the 1st order components (for example, if I'm too lazy to put in multiple decoders, I use a 3rd order decoder, and simply pipe in the 1st order to the first 4 inputs.) and it works not too bad. But I'm aware that it's a bodge job, and certainly not appropriate for precision work

cheers


Dr. Peter Lennox
Senior Fellow of the Higher Education Academy
Senior Lecturer in Perception
College of Arts
University of Derby

Tel: 01332 593155
________________________________
From: Sursound <sursound-***@music.vt.edu> on behalf of James Anthony Enda Bates <***@tcd.ie>
Sent: 07 February 2017 19:54:42
To: ***@music.vt.edu
Subject: [Sursound] Going from 3rd order to 1st order.

Hi everyone,
so it seems to be very common practice now to convert from 3rd order to
1st order by simply using the first 4 channels of the 3rd order stream.
However, I have this very vague recollection of that not being quite right
and that there are some differences between the WXYZ channels in different
orders? But I cant seem to pinpoint the reference or source for that, so
perhaps my memory is just wrong?
Any one have any ideas on this? Could this be an issue with Furse-Malham,
rather than Ambi-X, or am I just completely wrong about that?

It's quite a relevant question as you often need to prepare both 1st and
3rd order mixes these days for 360 videos.
Thanks all,
enda




--

Dr. Enda Bates
Teaching / Research Fellow
Music & Media Technologies / School of Engineering
Stack B, IFSC, Dublin 1, Ireland.

+353 1 896 1434
***@tcd.ie
www.endabates.net<http://www.endabates.net> <http://www.endabates.net>www.tcd.ie
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Fons Adriaensen
2017-02-07 22:16:05 UTC
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On Tue, Feb 07, 2017 at 07:54:42PM +0000, James Anthony Enda Bates wrote:

> so it seems to be very common practice now to convert from 3rd order to
> 1st order by simply using the first 4 channels of the 3rd order stream.
> However, I have this very vague recollection of that not being quite right
> and that there are some differences between the WXYZ channels in different
> orders? But I cant seem to pinpoint the reference or source for that, so
> perhaps my memory is just wrong?

It is. First order signals are just a subset of any higher order.

> Any one have any ideas on this? Could this be an issue with Furse-Malham,
> rather than Ambi-X, or am I just completely wrong about that?

That's an entirely separate issue. If you take for example the first
four channels of third order Ambix set, you get an Ambix first order
order signal. Then if you need FuMa first order you need to adjust
the W gain.


A different matter is e.g. using a higher order decoder with only a
first order signal, or mixing a first order signal into a higher
order one. Then for best results you need to modify the first order
signals. This may be what you remember.

Ciao,

--
FA

A world of exhaustive, reliable metadata would be an utopia.
It's also a pipe-dream, founded on self-delusion, nerd hubris
and hysterically inflated market opportunities. (Cory Doctorow)
Peter Lennox
2017-02-07 22:17:14 UTC
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Wot he said...


Dr. Peter Lennox
Senior Fellow of the Higher Education Academy
Senior Lecturer in Perception
College of Arts
University of Derby

Tel: 01332 593155
________________________________
From: Sursound <sursound-***@music.vt.edu> on behalf of Fons Adriaensen <***@linuxaudio.org>
Sent: 07 February 2017 22:16:05
To: ***@music.vt.edu
Subject: Re: [Sursound] Going from 3rd order to 1st order.

On Tue, Feb 07, 2017 at 07:54:42PM +0000, James Anthony Enda Bates wrote:

> so it seems to be very common practice now to convert from 3rd order to
> 1st order by simply using the first 4 channels of the 3rd order stream.
> However, I have this very vague recollection of that not being quite right
> and that there are some differences between the WXYZ channels in different
> orders? But I cant seem to pinpoint the reference or source for that, so
> perhaps my memory is just wrong?

It is. First order signals are just a subset of any higher order.

> Any one have any ideas on this? Could this be an issue with Furse-Malham,
> rather than Ambi-X, or am I just completely wrong about that?

That's an entirely separate issue. If you take for example the first
four channels of third order Ambix set, you get an Ambix first order
order signal. Then if you need FuMa first order you need to adjust
the W gain.


A different matter is e.g. using a higher order decoder with only a
first order signal, or mixing a first order signal into a higher
order one. Then for best results you need to modify the first order
signals. This may be what you remember.

Ciao,

--
FA

A world of exhaustive, reliable metadata would be an utopia.
It's also a pipe-dream, founded on self-delusion, nerd hubris
and hysterically inflated market opportunities. (Cory Doctorow)

_______________________________________________
Sursound mailing list
***@music.vt.edu
https://mail.music.vt.edu/mailman/listinfo/sursound - unsubscribe here, edit account or options, view archives and so on.


The University of Derby has a published policy regarding email and reserves the right to monitor email traffic.
If you believe this was sent to you in error, please reply to the sender and let them know.

Key University contacts: http://www.derby.ac.uk/its/contacts/
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