Discussion:
Mosca: GUI assisted ambisonics quark v0.2 for SuperCollider
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Iain Mott
2018-02-12 12:39:49 UTC
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Hello list,

For users of SuperCollider:

A new and much improved "Mosca" quark for GUI assisted ambisonics is
available in the quark repository. It has been tested with the ATK 4.0.1
and SC 3.9.0.

Version 0.2 includes optional head-tracking, streaming from disk,
non-GUI operation, a code interface and many other changes and bug fixes.

The home page for the project is here: http://escuta.org/mosca

A video tutorial is available here: http://escuta.org/moscavideo

The git source is here: https://github.com/escuta/mosca

All the best!

Iain Mott
--
_________
Iain Mott
http://escuta.org
Bo-Erik Sandholm
2018-02-14 18:43:20 UTC
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Looks very nice.
I have looked through the video
Seems like I have to start learning SuperCollider :-)

I do have a headtracker design and Javascript code currently generating
quaternions over BLE presenting the result in a websocket. The design will
released in the near future.

As I understand it there is no support for individul SOFA files in ATK ?
Could "someone" take on the effort to do this?
As I am not a programmer on the level to do something like this, but I
wonder if
https://www.npmjs.com/package/ambisonics#sofa might not be of great help
in that effort?

Or is there a simple way to send a output stream of bformat sound from
SuperCollider to an external instance of the SOFA capable decoder written
in JavaScript??

I currently have a personal SOFA file created for me by Antti Pulkki's
company.

Best Regards

Bo-Erik Sandholm
Stockholm, Sweden
Post by Iain Mott
Hello list,
A new and much improved "Mosca" quark for GUI assisted ambisonics is
available in the quark repository. It has been tested with the ATK 4.0.1
and SC 3.9.0.
Version 0.2 includes optional head-tracking, streaming from disk, non-GUI
operation, a code interface and many other changes and bug fixes.
The home page for the project is here: http://escuta.org/mosca
A video tutorial is available here: http://escuta.org/moscavideo
The git source is here: https://github.com/escuta/mosca
All the best!
Iain Mott
--
_________
Iain Mott
http://escuta.org
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Joseph Anderson
2018-02-14 19:48:51 UTC
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Hello Bo-Erik,

I'll just add some quick inline responses below... which will hopefully be
useful....


As I understand it there is no support for individul SOFA files in ATK ?
Post by Bo-Erik Sandholm
Could "someone" take on the effort to do this?
The ATK team will be very pleased to offer SOFA support. Among other things
that would really help to position the ATK as a "one stop shop" for
composers working with Ambisonics... which is our end goal. (I call that
the ATK as kitchen sink included solution.)

At the moment the ATK team is pushing forward on HOA implementation for
ATK-SC3. If you're nosey, you can peek in sandbox/hoa
<https://github.com/ambisonictoolkit/atk-sc3/tree/sandbox/hoa> to see
what's happening at the moment. You can peek at the relevant classes in
development here
<https://github.com/ambisonictoolkit/atk-sc3/tree/sandbox/hoa/Classes>.
Note: all this is shifting sand... this week we're going to rename and
otherwise move things. The good news, ATK-SC3-HOA is coming....


Back to SOFA. There are a few issues that make this a non-trivial task. The
ATK is distributed with optimized encoding and decoding kernels. These are
available for download here
<http://www.ambisonictoolkit.net/download/kernels/>, and hosted in a
repository here <https://github.com/ambisonictoolkit/atk-kernels>. If we
inspect the folder for CIPIC
<https://github.com/ambisonictoolkit/atk-kernels/tree/master/FOA/decoders/cipic>,
we see subfolders named [Sample Rate] / [Kernel Size]. That is, CIPIC's
original HRTFs have been resampled for convenience. Looking further down,
192000/2048/0011/
<https://github.com/ambisonictoolkit/atk-kernels/tree/master/FOA/decoders/cipic/192000/2048/0011>,
we see that the 2 x 25 x 50 measurements (HRTF kernels) for CIPIC's subject
11 have been turned into just four two channel FIR filters, named
HRIR_W.wav, etc..

The process used to generate these resulting 8 FIRs (the FOA binaural
decoder) from 2500 (raw HRTF measurements) is outlined here
<https://github.com/ambisonictoolkit/atk-kernels#decoders>. Repeating info
Post by Bo-Erik Sandholm
1. DC - LF: omni-directional, W only.
2. LF - 700Hz: strict soundfield, aka basic. Retain phase.
3. 700 - 2000Hz: maximum energy, aka max rE. Retain phase.
4. 2000 - 18000Hz: strict soundfield, aka basic. Discard phase.
5. 18000Hz - Nyquist: response patterns measured from 4., at 18000Hz.
LF = 35Hz for CIPIC
Measured decoders are designed to compensate for the proximity (near-field
effect) of the two HRTF measurement systems. Asymmetry, across all axes,
found in the measured HRTFs is preserved.
In other words, the ATK's HRTF decoders are not "virtual speaker" decoders.
We do the above to make "optimized" decoders that "sound transparent". We
do plan to eventually re-write and publish the code that does the above,
and in the context of coming ATK HOA HRTF decoders, we are planning to
re-address the issue.

So.. SOFA support...? What that will probably mean is that a user will (at
first) probably run a routine that will generate an ATK optimized HRTF
decoder kernel set given a SOFA file....

In the short term, "not so optimized" decoders (aka virtual speaker) from
HRTF are not difficult to create. To turn an HRTF set into a decoder
suitable for ATK-SC3, just generate the relevant kernels for given
harmonics. E.g., lm pairs. The resulting kernels just then need to be
convolved... and you've got a decoder (that needs some more work to sound
good).


As I am not a programmer on the level to do something like this, but I
Post by Bo-Erik Sandholm
wonder if
https://www.npmjs.com/package/ambisonics#sofa might not be of great help
in that effort?
Possibly... Archontis Politis's
<https://www.researchgate.net/profile/Archontis_Politis> code is well
written. We do view his work as a reference.


Or is there a simple way to send a output stream of bformat sound from
Post by Bo-Erik Sandholm
SuperCollider to an external instance of the SOFA capable decoder written
in JavaScript??
Probably not difficult to do with Jack <http://www.jackaudio.org/>.



My best,
Jo


*Dr Joseph Anderson | Research Scientist*

DXARTS, Box 353414

University of Washington

Seattle, WA 98195-3680



http://www.dxarts.washington.edu


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Politis Archontis
2018-02-14 22:11:34 UTC
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Hi Bo-Erik,

Just a small correction :-) - this is Archontis from Ville Pulkki’s group here in Aalto University, I think you meant Antti Vanne from IDA for personalized HRTFs (unless there is another spatial audio Pulkki here in Finland with the name Antti, offering also personalized HRTFs :-).

BR,

Archontis Politis
Post-doctoral Researcher
Department of Signal Processing and Acoustics
Aalto University
Finland

On 14 Feb 2018, at 20:43, Bo-Erik Sandholm <***@gmail.com<mailto:***@gmail.com>> wrote:

I currently have a personal SOFA file created for me by Antti Pulkki's
company.

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s***@mail.telepac.pt
2018-02-15 14:35:08 UTC
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Post by Politis Archontis
Hi Bo-Erik,
Just a small correction :-) - this is Archontis from Ville Pulkki’s
group here in Aalto University, I think you meant Antti Vanne from
IDA for personalized HRTFs (unless there is another spatial audio
Pulkki here in Finland with the name Antti, offering also
personalized HRTFs :-).
If I em entitled to speak for Bo-Erik... ;-) :

You are right.

He meant (of course) Antti Vanne of IDA, who did some (successful)
hrtf personalisation for Bo-Erik and us.

BR

Stefan (Schreiber)

------------------------
Post by Politis Archontis
BR,
Archontis Politis
Post-doctoral Researcher
Department of Signal Processing and Acoustics
Aalto University
Finland
On 14 Feb 2018, at 20:43, Bo-Erik Sandholm
I currently have a personal SOFA file created for me by Antti Pulkki's
company.
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