Hi ...
Here some expert view on the "technical background", presented by some
company in this area:
http://www.atsc.org/cms/pdf/pt2/07-Jean-Marc_Jot_3D_Audio.pdf
"Current state of the art".
Look for example to p. 6, "perceptual attributes that characterize
natural, 3D-audio".
(and especially "proximity" and "depth". How good is HOA at that?!)
High-order Ambisonics is mentioned (interestingly together with 22.2,
which is "fixed channel"; but should play together very well with HOA!)
p. 10: "surround sound virtuzalization for headphones or frontal
loudspeakers": the latter certainly based on X-talk cancellation,
Ambiophonics style.
I am getting increasingly aware of recent work on MPEG SAOC (spacial
audio object coding), also.
Moving Picture Experts Group
<http://en.wikipedia.org/wiki/Moving_Picture_Experts_Group> (MPEG)
issued a call for proposals on MPEG Spatial Audio Coding in March
2004. The group decided that the technology that would be the starting
point in standardization process, would be a combination of the
submissions from two proponents - Fraunhofer IIS / Agere Systems and
Coding Technologies / Philips.[5]
<http://en.wikipedia.org/wiki/MPEG_Surround#cite_note-mpeg-surround-tutorial-5>
...
MPEG Surround was also defined as one of the MPEG-4 Audio Object Types
<http://en.wikipedia.org/wiki/MPEG-4_Part_3#MPEG-4_Audio_Object_Types>
in 2007.[8] <http://en.wikipedia.org/wiki/MPEG_Surround#cite_note-8>
There is also the MPEG-4 Low Delay MPEG Surround object type (LD MPEG
Surround), which was published in 2010.[9]
<http://en.wikipedia.org/wiki/MPEG_Surround#cite_note-9>[10]
<http://en.wikipedia.org/wiki/MPEG_Surround#cite_note-saoc-ld-mpeg-surround-doc-10>
The Spatial Audio Object Coding (SAOC) was published as MPEG-D Part 2
- ISO/IEC 23003-2 in 2010 and it extends MPEG Surround standard by
re-using its spatial rendering capabilities while retaining full
compatibility with existing receivers. MPEG SAOC system allows users
on the decoding side to interactively control the rendering of each
individual audio object (e.g. individual instruments, vocals, human
voices).[2]
<http://en.wikipedia.org/wiki/MPEG_Surround#cite_note-mpeg-standards-2>[3]
<http://en.wikipedia.org/wiki/MPEG_Surround#cite_note-mpeg-terms-of-reference-3>[11]
<http://en.wikipedia.org/wiki/MPEG_Surround#cite_note-11>[12]
<http://en.wikipedia.org/wiki/MPEG_Surround#cite_note-12>[13]
<http://en.wikipedia.org/wiki/MPEG_Surround#cite_note-13>[14]
<http://en.wikipedia.org/wiki/MPEG_Surround#cite_note-14>[15]
<http://en.wikipedia.org/wiki/MPEG_Surround#cite_note-15> There is
also the Unified Speech and Audio Coding
<http://en.wikipedia.org/wiki/Unified_Speech_and_Audio_Coding> (USAC)
which will be defined in MPEG-D Part 3 - ISO/IEC 23003-3 and ISO/IEC
14496-3:2009/Amd 3.[16]
<http://en.wikipedia.org/wiki/MPEG_Surround#cite_note-16>[17]
<http://en.wikipedia.org/wiki/MPEG_Surround#cite_note-17> MPEG-D MPEG
Surround parametric coding tools are integrated into the USAC
codec.[18] <http://en.wikipedia.org/wiki/MPEG_Surround#cite_note-18>
Source:
http://en.wikipedia.org/wiki/MPEG_Surround
Now some recent AES "input":
http://www.aes.org/technical/documentDownloads.cfm?docID=418
Because some of the established players are already presenting their own
proposals (Fraunhofer Institut being very close to the MPEG/ISO anyway,
because of standard-defining work on perceptional audio compression
etc.), it might be a good strategy to define an open source 3D audio
("next gen. surround sound") proposal based on Ambisonics/HOA - just
forgetting the patent issues which might even not exist anyway. This
open standard could be included into other standards - and last but not
least - software and hardware products.
As nobody seems to "own" Ambisonics technology, I think an open source
solution for 3D audio based on Ambisonics would fit well to Xiph.org and
it's recent work on audio codecs/technology, including the newish "Opus"
codec recognised by the IETF as official Internet audio standard.
http://en.wikipedia.org/wiki/Opus_%28audio_format%29
If this makes sense or not, we have/had to look what happens elsewhere.
My "political" view would be that HOA doesn't seem to have some big
"lobby" at the MPEG/ISO, which might be biased heavily to parametric and
object-based solutions, see MPEG-D part 1 and even more part 2...
Now everybody should be confused including myself, after some serious
"standard name dropping" ... :-)
Best regards
Stefan
P.S.: USAC (Unified Speech and Audio Codec), part 3 of MPEG-D , could
have a new and very powerful competition in IETF's/Xiph's (free) Opus
Codec.
Note that Opus includes some propietary technology for speech
compression, which has been "gifted" by evil Microsoft.
Now M$ is a bit less evil... Your view on this, Gregory? ;-)
Gregory Maxwell wrote:
On Sun, Jan 20, 2013 at 6:09 PM, Stefan Schreiber <st...@mail.telepac.pt> wrote:
This is a typical FUD approach presentend by the competition.
If I have anything to say about, I'd say that any Ambisonis based approach
would be "patent-light", iof not patent-free.
You confirm precisely the concern I raised: The result would likely be
a royalty bearing format. How can you accuse me of FUD while
concurrently affirming the concern I raised?
If people believe there is a market for ambisonic distribution which
has less than lossless quality but only if the bitrate is low enough
then the parties who would profit from that should cooperate to
produce a royalty free format so that their success will not be
saddled with additional friction which will keep ambisonics in a
niche. AAC + mpeg surround licensing costs over $1 decoder unit— to be
added on top of the additional hardware costs (more DSP cpu cycles)
required. Because the market for this technology barely exists the
licensing costs could quite possibly keep it in a non-existing state.
I think surround advocates would very much like it if support ended up
in everything because the cost of doing so is only a modest hardware
bump and some one time integration and testing costs. Per-unit
royalties or even just the cost of negotiating a flat rate license
strongly discourage deployment.
In some markets like support in web browsers or in Free software which
are distributed at no direct cost any royalty at all is a major or
absolute barrier.
I think it would be irrational for anyone who wants there to be a
market for this to contribute to the development of a royalty bearing
effort. You may disagree, but I still do not think it should be a
concern which goes without mention. If pointing to an elephant in the
room makes me guilty of FUD then so be it.
P.S.: 1st order Ambisonics should be patent-free, nowadays.
Higher orders can't be "overpatented", because the theory behind is quite
old. Certainly more than 20 years back...
Yes, they are _now_. I think it would be a shame to revert ambisonics
back to the bad— harder to deploy— state where including support for
the distribution format required unfortunate per-unit or
per-organization royalties and burdensome license negotiation.
P.S. 2: And I for my part didn't patent "Ambisonics of order >=2 + front
channels"... Promised! :-D
Thank you for not being personally evil. :P
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