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-dsr-
June 22nd 17, 03:06 PM
While reading a page on recent changes in Opus, a freely-available
codec, I came across a reference to Ambisonics:


There is ongoing work at IETF to define an ambisonics mapping for
Opus at IETF. That new mapping isn't formally standardized yet,
but Opus 1.2 currently supports the latest version of the draft for
direct coding of ambisonics channels (mapping family 2), with the
matrix-based coding method (mapping family 3) still in development.

Ambisonics is a technique for representing spatial audio based
on spherical harmonics rather than relying on fixed loudspeaker
locations (like 5.1 surround). It was never very popular compared
to other formats for applications like movies. So why care about
Opus ambisonics? The answer is virtual reality (VR). With VR we no
longer have fixed speakers. What we want is a representation of the
entire sound field that can then be converted to a stereo signal
based on the correct orientation of the user's head. It turns out
that representing sound fields is something that Ambisonics is good
at. So expect to see Opus getting more popular for VR.

--- from https://jmvalin.ca/opus/opus-1.2/

IETF is the Internet Engineering Task Force, the volunteer group
that establishes RFC standards.

The changes to Opus described here are mostly about low-bandwidth fidelity
improvements.

-dsr-

Peter Wieck
June 30th 17, 08:24 PM
Descriptions in the literature kinda-sorta remind me of the Hafler Circuit a bit. Sum-difference sound distribution, only with a lot more technology applied.

https://en.wikipedia.org/wiki/Hafler_circuit

I keep an original Dynaquad device (as well as a fully operational Advent 500). Perhaps I should hook them up? I have plenty of speakers and amps to do so.

Thoughts?

Peter Wieck
Melrose Park, PA