On 6/6/24 11:38, Juan Reyes wrote:
Hi Anders,
Thanks a lot for your thorough explanation which of course as usual is
useful and encouraging. What I was looking for was something like
'tetrafile'. (Been using other Fons' software for a while and don't know
how I overlooked at it).
Need to encode few dozen sound files into B-format Ambisonics and batch
processing would be a time saving alternative.
Hey Juan,
I am assuming you need A-format (capsule signals) to B-format
(Ambisonics) conversion. As Anders wrote, that is heavily dependent on
which Ambisonics microphone was used to record the soundfield.
Which one did you use?
-- Fernando
Will be following your
suggestions.
However, while searching this topic, can't help pointing out Fernando's
Ambisonics code in 'dlocsig.clm (scm)'.
-- Juan
If all you want is the MS-type matrixing it should be straight
forward in an "a2b.scm" script for snd, or sox or ffmpeg or others,
You can combine the 4 A-format channels FLU,FRU,BLU,BRD using
MS-like-techniques:
W = FLU+FRD+BLD+BRU X = FLU+FRD-BLD-BRU Y = FLU-FRD+BLD-BRU Z =
FLU-FRD-BLD+BRU
But leaving out all the required tunings for A2B conversion from any
given FAO mic: eq, gain, phase - you wont get any meaningful
B-format output - rather a
"quite-nice-space-like-feeling-surround-spread mic" (wow, my new
brand! :-) .
For B-format you'll need a specific B-format encoder to a specific
type of mic, tuned to its geometry and specs of capsules, and further
using precise calibration-data fitted to your personal mic (*).
Fons Adriansens 'tetraproc' includes a CLI 'tetrafile', doing the
A-B conversion for Core Sounds Tetramic, and similar for their
2nd-order Octomic. I think he has some example *.tetra config-files
for some other brands. He also offers to do the necessary
measurements and calibrations for your TetraMic to plug into his
conversion tools.
Not sure what the other brands - Sennheiser, Röde etc. - offers for
CLI-versions of their tools.
(*) The dependence on both a specific decoder for a mic-brand, and
further individually calibrated per mic, is perhaps sub-realised?
Strange, given Ambisonics 100% reliance on extremely exact phase and
gain info to represent the recorded space.
One example is Nevaton who provides their VR-mic - otherwise very
nicely made with great sound (no-noise, full-range - and very
expensive) - without neither a fitting A2B decoder or necessary
calibration data for each mic, relying on a one-time measurement of
one mic done by Angelo Farino. They even have suggested using
Sennheisers or Röde's standard A2B-encoder...
-anders
_______________________________________________
Cmdist mailing list
Cmdist@ccrma.stanford.edu
https://cm-mail.stanford.edu/mailman/listinfo/cmdist
_______________________________________________
Cmdist mailing list
Cmdist@ccrma.stanford.edu
https://cm-mail.stanford.edu/mailman/listinfo/cmdist
