Hi,
It is hardly surprising that "I hear directional information and head
tracking effects, but have never experienced the externalization and
verisimilitude that direct dummy head or Algazi and Duda's motion-
tracked binaural recordings can produce."
Even software direct binaural encoding seems more 'accurate' than B-
Format ambisonics recoded to binaural. Then Algazi and Duda's system
uses binaural recordings, and they know what they're doing.
Decorrelation, and software reverb, can help with a sense of
externalisation, though you can go too far.
Ciao,
Dave Hunt
From: Aaron Heller <hel...@ai.sri.com>
Date: 4 June 2016 20:53:09 BDT
To: Surround Sound discussion group <sursound@music.vt.edu>
Subject: Re: [Sursound] Using Ambisonic for a live streaming VR
project
My experience with FOA-to-binaural rendering is pretty much the
same as
what Acrhontis says. I hear directional information and head
tracking
effects, but have never experienced the externalization and
verisimilitude
that direct dummy head or Algazi and Duda.'s motion-tracked binaural
recordings can produce.
Aaron (hel...@ai.sri.com)
Menlo Park, CA
On Sat, Jun 4, 2016 at 2:31 AM, Politis Archontis <
archontis.poli...@aalto.fi> wrote:
Hi Jörn,
On 03 Jun 2016, at 15:27, Jörn Nettingsmeier
<netti...@stackingdwarves.net
<mailto:netti...@stackingdwarves.net>> wrote:
Note however that while the quality of first-order to binaural is
quite
good because the listener is by definition always in the sweet spot,
first-order over speakers can be difficult for multiple listeners
when
they're far outside the center.
This is by no means meant to provoke, but I have never managed to
hear a
convincing B-format to binaural rendering, or to produce one
myself. Could
you possibly share some info on the decoding approach that you
used that
results in a good example?
In my experience, no matter how much tweaking in the decoding,
there is
severe localization blur, due to the large inherent spreading of
directional sounds, and low envelopment due to the wrong (high)
coherence
in the binaural signals with reverberant sound, compared to the
actual
binaural coherence. And there is also serious colouration, with a
loss of
high-frequencies, that seems direction-dependent. The fact that
everything
is on the ideal sweet spot under free-field conditions doesn’t
seem to
improve much, it actually seems to do more harm (I believe that a
small
amount of natural added decorrelation from a room and tiny
misalignments
from speakers etc. seem to improve binaural coherence and the
perceptual
quality somewhat of loudspeaker B-format reproduction).
Listening to a binaural rendering from a real B-format recording
is not so
bad, there is no reference for comparison, but for VR the
difference I’ve
heard between using directly HRTFs and B-format rendering is huge.
And as
many of these applications rely on sharp directional rendering with
accurate localization of multiple sound events, traditional B-format
decoding seems unsuitable to me. The performance improves somewhat
with
2nd-order rendering, and significantly with 3rd and 4th-order
rendering.
Also it improves dramatically using plain B-format with a well-
implemented
parametric active decoder, such as HARPEX or DirAC.
So my guidelines for VR till now have been,
a) if bandwidth is not an issue go for HOA rendering (at least 3rd-
order),
b) if it is an issue, like the streaming application of the OP,
stream
B-format and use an active decoder at the client side.
But I’d like to hear many opinions on this too, and any counter
examples!
Regards,
Archontis Politis
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