[LAU] ssr and alternatives

Brandon Hale bthaleproductions at gmail.com
Mon Mar 1 17:40:55 CET 2021

I didn't know you could do that. Thanks for changing my life and 
teaching me about this Peter.

Brandon Hale

On 3/1/21 11:27 AM, Peter P. wrote:
> * Brandon Hale <bthaleproductions at gmail.com> [2021-03-01 16:53]:
>> Thanks for all of this good info Peter. I didn't know about the sursound
>> mailing list, and will experiment with that pd library you told me about.
>> This is all a learning experience for me.
>> When you say 5th order 3d, wouldn't that only be 36 loudspeakers?
> The basic relation you have to consider is this classic one:
> In order to reproduce a 2D soundfield (planar, loudspeaker ring) of
> order N you need at least L loundspeakers
> (N+1)^2 =< L
> so for 5th order it would be 6^2 = 36 as you mention, but thanks to the
> greater-equal sign you can always use more speakers. You will not
> exploit a possibly higher order, but as Fons remarked, there might not
> be much spatial resolution to gain.
> Give it a try, perhaps subscribe to the pd list for more help with the
> objects if needed, and take a listen.
> cheers, P
>> Brandon Hale
>> On 3/1/21 10:12 AM, Peter P. wrote:
>>> Hi,
>>> * Brandon Hale <bthaleproductions at gmail.com> [2021-03-01 15:37]:
>>>>> 1. Computing decoders for arbitrary speaker positions is still some
>>>>> sort of 'black art' unless the postions form a more or less regular
>>>>> grid. Don't believe everything about automated methods claiming to
>>>>> do this.
>>>> This is good to keep in mind. Have you ever seen the ICST plugins for max
>>>> msp? Those objects have a method of putting in xyz coordinates for its
>>>> ambisonic decoders.
>>> I think Fons means that building "good" decoders is some sort of a black
>>> art for a given (non-regular) layout. All technical solutions allow xyz
>>> coordinate entry and come up with a static decoder matrix (this is
>>> really just a matrix of static floating point numbers, you could write
>>> this on a beer mat if pubs were open).
>>>> Where I work at, we use this to output ambisonics to all
>>>> of our spaces at ICAT, including the Cube
>>>> <https://icat.vt.edu/studios/the-cube.html>. It does work well, but I do
>>>> know of colleagues who complain about how "fuzzy" the spatialization is. Do
>>>> these kinds of decoders fudge the decoding to achieve output? I really want
>>>> to find something like this for Linux.
>>> If you want to get the full craze of kinds of decoder discussions you
>>> might want to sign up to the sursound mailing list.
>>>>> 3. I really can't imagine anything done with speakers that would
>>>>> require 7th order. Even with 4th or 5th order, if you have enough
>>>>> speakers to use that, the angles between the speakers are so small
>>>>> that even phantom images in between speakers are for all practical
>>>>> purposes perfect.
>>>> The reason I ask is because I want to find a Linux-based system for the
>>>> Cube, which has 138 speakers arranged in a rectangular prism. I am
>>>> constantly looking for a way to decode ambisonics to it without having to
>>>> use max msp.
>>> Use the Pd objects I mentioned and go for 5th order 3D which will create
>>> output signals for all 138 speakers. Also correct the
>>> speaker distances with short delays and compensate for level differences
>>> by ear or by using a SPL meter.
>>>> I have not had much luck finding something standalone or in pd.
>>>> Maybe I should learn supercollider? It can be hard to find decoders that go
>>>> to 10th or 11th order.
>>> Again, its not a question of max vs pd vs sc3 vs csound, but of the
>>> usefulness of doing it. If you already have these 138 speakers mounted,
>>> then configure one of the mentioned solutions to use the corresponding
>>> order and have a listen.
>>>>> 4. To do anything similar to WFS 'internal sources' (i.e. in front
>>>>> of the speakers) in any practical frequency range, you'd need the
>>>>> same amount of speakers as WFS would, and of course the required
>>>>> very high order input.
>>>> At work, I may be getting hold of 64 AVB speakers that I can arrange in a
>>>> line to experiment with WFS. The great thing about this is the speakers are
>>>> AVB, and not Dante. I may be able to play with these speakers on Linux. Of
>>>> course, there is at least one WFS processor (is that the right term?) that I
>>>> know of in max. But, I find max too annoying and locked down for real use,
>>>> and of course I want to do it on Linux!
>>> I managed to get ssr~ to run as a pd external a few years ago.
>>> Furthermore be aware that the distance between the speakers determines
>>> the upper frequency limit. I don't know if AVB introduces some latency
>>> between speakers. Fons might know something about this perhaps?
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