Hi Stefan,
I doubt if B+ would meet the currently perceived needs of cinema
surround mixers/producers since it does not have the ability to go
"discrete". B++ might be enough - that's first order + 5.1 (I just
made that up :-)). A better option would be at least third order,
preferably fifth - to get the most bang for buck - but to fit in the
22.2 channels that seem to be coming over the horizon fast, maybe
fourth would work better in terms of channel count.
I don't, personally, think that first order is a good choice for
cinema for anything other than home use. It certainly can be pressed
into use for large areas (been there, done that, got not just the T
shirt but the entire wardrobe) but it would really struggle in
anything other than the smaller art cinemas. The biggest limitation to
the whole thing is the availability of higher order microphones,
though Eigenmikes are becoming more widely available and one can hope
that Peter Craven's new ideas
(http://www.findaphd.com/search/ProjectDetails.aspx?PJID=40193) pan
out and give us at least a good second order microphone. However, if
you are constructing the soundscapes entirely from scratch, such
considerations do not really matter - in fact, to that end, improving
the use of spot microphones to generate convincing, realistic higher
order recordings is probably at least as important.
On audio objects and where they should be mixed in, I have some
sympathy with your point that they should only be used in the studio
but in purely practical terms (and, again, only really for non-home
use) they can be very useful at the decoding stage where you are
dealing with very irregular arrays, so don't rule them out.
All the best
Dave
On 20 January 2013 04:11, Stefan Schreiber <st...@mail.telepac.pt> wrote:
> Reading back, and evaluating...
>
> http://steinhardt.nyu.edu/scmsAdmin/uploads/005/384/Miles_Fulwider_Thesis.pdf
>
> I believe B+ "classic" could serve as a convincing "1st" proposal for a
> sound-field based 3D cinema audio system. (And therefore, as a general
> surround format).
>
> The very obvious changes "could"/would be:
>
> - You have at least 3 front channels behind the screen (up to 5 in Dolby
> Atmos), not 2
>
> - Which Ambisonics order would you need for cinema use? Might even 1st order
> suffice (provided there is a "direct"/precise front)
>
> - LFE channel(s) should (probably) be treated in a simple
> channel-loudspeaker "configuration", such as the front channels. (You also
> could code an "LFE soundfield", B format style. Or you don't code LFE at all
> - but we are talking about cinema use, in which case LFE seems to matter.)
>
> - If using a sound field approach, you would not want to mix soundfields
> this with audio objects at rendering time. (Rather, use audio objects in the
> studio. Mixing stage, not decoding stage...)
>
> - The "object audio" proposals are all driven by the need to cope for many
> different loudspeaker layouts. This issue is no problem for
> Ambisonics/soundfields...
> (Could say much more about this point, but it is too late, and why should
> I... :-) )
>
>
> Best,
>
> Stefan Schreiber
>
>
>
>
>
>
> Richard Furse wrote:
>
>> Very interesting post & following discussion.
>>
>> I've actually been added very recently to the IST/37 committee, which
>> apparently is a close relative to the MPEG one. However, I've not talked
>> to
>> any other members so far and I'm not sure how all this stuff works just
>> yet!
>>
>> In other news, I spent a bit of time last year putting together a C API
>> for
>> object streaming etc (including Ambisonics). Hopefully it roughly captures
>> the suggestions/requirements below. This project is now in a state where
>> there's a fairly short API that seems to work and a basic SDK which
>> provides
>> some basic reference tools like a simple stereo renderer, lossless file
>> format and network streaming. However, this isn't part of the API/Spec
>> itself - the intent is that the C API should be independent of actual
>> rendering/stream/persistence formats (although a reference is provided),
>> so
>> would hopefully play nice with Atmos/MDA. That said, I've not seen a
>> *technical* spec for either of these yet, so there's a fair bit of
>> guesswork
>> happening. Certainly what's there now seems to work well for me, so far.
>> :-/
>> The provisional spec has been bounced off a few folk but I've not heard
>> much
>> back (though I also had some email problems at a similar time). I'm
>> wondering about releasing the API and SDK using some kind of open source
>> license. Anyway - if folk are interested in more detail, please get in
>> touch
>> off-list!
>>
>> Best wishes,
>>
>> --Richard
>>
>>
>> -----Original Message-----
>> From: sursound-boun...@music.vt.edu [mailto:sursound-boun...@music.vt.edu]
>> On Behalf Of Stefan Schreiber
>> Sent: 06 January 2013 02:00
>> To: Surround Sound discussion group
>> Subject: [Sursound] A proposal for an Ambisonics based 3D audio codec,
>> MPEG/ITU style...
>>
>> Dear colleagues...
>>
>> I would like to remember everybody interested or already being involved
>> that ITU/MPEG plan to define and issue some 3D audio standard (better: 3D
>> audio standard framework) during this year. The 3D audio codec is meant to
>> be part of the (wider) MPEG-H standard.
>>
>> This all makes a lot of sense, 'cos ;-) there is already some
>> competition around:
>>
>> 1. Hamasaki 22.2, well known as (audio) part of former UHDTV (Super
>> Hi-vision) proposals.
>>
>> 2. http://www.auro-3d.com/system/listening-formats
>>
>> (Note:
>>
>> a)
>>
>>
>>>
>>> The Auro-3D® Engine comprises:
>>>
>>> Auro Codec: The revolutionary codec that delivers native, discrete
>>> Auro-3D® content.
>>>
>>> Auro-Matic: The groundbreaking up-mixing algorithm that converts legacy
>>> content into the Auro- 3D® format.
>>>
>>> Auro-3D® Headphone: Like other audio configurations, similar results can
>>> be achieved with headphones that use binaural technology.
>>
>>
>> b)
>>
>>
>>>
>>> Film, Broadcast, Gaming, Mobile, Automotive and Multimedia industries are
>>> all searching for a next generation sound format. With 3D Stereoscopic
>>> imagery becoming commonplace, the time is right for an audio experience that
>>> matches this increased level of fidelity. Sound in 3D is clearly the next
>>> step.
>>
>>
>>
>>
>> 3. http://www.dolby.com/us/en/consumer/technology/movie/dolby-atmos.html
>>
>> (IMHO, Dolby won't participate in the MPEG standardization process. And
>> even if, Dolby Atmos seems to be finished.)
>>
>>
>>
>> The current situation at MPEG:
>>
>> http://www.itu.int/en/ITU-T/studygroups/com16/video/Pages/jctvc.aspx
>>
>> Next meetings:
>>
>>
>>>
>>> * Geneva, Switzerland, October 2013 (tentative)
>>> * Vienna, Austria, 27 July - 2 August 2013 (tentative)
>>> * Incheon, Korea, 20-26 April 2013 (tentative)
>>> * Geneva, Switzerland, 14-23 January 2013 (tentative)
>>>
>>>
>>
>>
>> During the next conference (January, Genève), the important HEVC codec
>> should be technically finished. (Status: FDIS, for "Final Draft
>> International Standard")
>>
>>
>> There will also be issued a final call for an 3D audio codec:
>>
>>
>>>
>>> At the 102nd MPEG meeting MPEG has issued a Draft Call for Proposals
>>> (CfP) on 3D Audio Coding.
>>
>>
>> (This was the last meeting, Shanghai, October 2012)
>>
>>
>>>
>>> MPEG-H 3D Audio is envisaged to provide a highly immersive audio
>>> experience to accompany the highly immersive experience provided by MPEG-H
>>> HEVC. Such an immersive listening experience will be realized by the
>>> rendering of a realistic and compelling 3D audio scene either by using a
>>> large number of loudspeakers, such as for 22.2 channel audio programs, or by
>>> using headphones supporting binauralization. Key issues to be addressed are
>>> a compact and bit-efficient representation of multi-channel audio programs
>>> and the ability to flexibly render an audio program to an arbitrary number
>>> of loudspeakers with arbitrary configurations. 3D Audio support via
>>> headphones is also a key capability in order to deliver an immersive
>>> experience for users of mobile devices.
>>> A final CfP will be issued at the 103rd meeting in January 2012,
>>
>>
>> (they mean January 2013, of course...)
>>
>>
>>>
>>> with selection of technology from amongst the responses received at the
>>> 105th meeting in July 2013. This technology will form the basis for MPEG-H
>>> 3D Audio, the Audio part (Part 3) of the MPEG-H (ISO/IEC 23008) suite of
>>> technologies.
>>>
>>
>>
>>
>> Taken together, the final deadline for any proposal seems to be around
>> April 2013. (Incheon, Korea meeting, April 2013)
>>
>>
>> If some Ambisonics based audio-codec is proposed (it has been done, but as
>> an official proposal??), I would like to add some observations.
>>
>> Cinema audio and UHD TV (and this is where the push comes from) iclude
>> some "discrete" elements, and anybody has to be aware of this. Firstly,
>> there are one or two (Hamasaki 22.2) separate LFE channels. (LFE channels
>> make sense for movies and in the cinema, even if some people always will
>> dispute this...we are not talking about most music you will listen to at
>> home, but about cinema sound with special effects.)
>>
>> Secondly, a lot of sound is tied to the screen. The narrow-spaced front
>> speakers might represent a problem for Ambisonics, at least for low-order
>> Ambisonics. (Dolby Atmos defines actually up to 5 "screen" loudspeakers,
>> this means three or five. Note that the front C channel is often used as
>> voice/conversation channel.)
>>
>> A possible solution would be to offer some kind of B"+" option, the "plus"
>> part being the front and LFE channels. 2D/3D surround for all the "resting"
>> sound field would be offered via the B format (order?) sound field, or HOA
>> sound field. (To mix such a hybrid sound format is rather trivial, I would
>> say. Just leave out the front and the LFE parts in the surround/3D field...
>> )
>>
>> So maybe define some "purist" solution (say B format 3rd order, or
>> horizontal 4th order mixed with vertical 1st/2nd order, or whatever), and
>> also some "B+" option. (The original B+ proposal was FOA + 2 stereo
>> channels. Note that a direct consequence of the "hybrid" Ambisonics option
>> would be that a 2nd or 3rd order soundfield should be enough for the
>> representation of the surround and height channels. In fact, you can decode
>> to 5.1, 7.1 Hamasaki 22.2, Auro-3D and Dolby Atmos surround layouts. The B
>> format "resolution" should be more than enough for any of these layouts -
>> maybe even at 2nd order, certainly at 3rd. The narrow-spaced front wouldn't
>> be any problem, by definition. LFE channels are discrete in any case, as
>> stated before.)
>>
>> I would't be afraid to offer some hybrid option, anyway. (Dolby Atmos
>> defines up to 64 channels, and also audio objects for different loudspeaker
>> layouts. Therefore, Dolby Atmos is itself a hybrid system - based on
>> discrete channels and audio objects.)
>>
>>
>> I just wanted to give a small hint ;-) how anybody might set up a valid
>> proposal. The B+ could and < should > be included as an option. The basic
>> idea behind for this is that cinema audio has some specific properties,
>> which have to be covered by any system. (The < front > is extremely
>> important, because voice and many sounds are tied to events on the screen;
>> LFE channels are discreet; the C channel is mostly used in a discreet way,
>> being used as the voice channel.)
>>
>>
>> Note also that the clock is already ticking, and I absolutely mean this.
>> The MPEG can chose from some valid proposals, (Hamasaki) 22.2 and Auro-3D
>> among these.
>>
>> Ambisonics is defining a 3D audio field since the 70s, so it would seem
>> logic to include Ambisonics into any 3D audio standard. There are also some
>> clear advantages, which are getting more and more important. (Different
>> cinemas won't offer anywhere the same loudspeaker layouts, pretty safe bet)
>>
>> Because the MPEG will basically chose from existing proposals, somebody
>> has to define some valid Ambisonics based proposal.
>>
>> I am apologizing to the already involved experts to have written on a
>> pretty basic or say introductory level. But nobody has done this here
>> before, and I think not everybody is sufficiently informed about these
>> issues - maybe even some very competent people.
>>
>> However/but:
>>
>> The next two or three MPEG conferences are not just like the next spacial
>> audio or Linux audio conference ;-) , we are talking (also) about the
>> probable next real-world standard for 3D audio. After MPEG-H 3rd part
>> (audio) and Dolby Atmos exist, every future endeavour would face some
>> (extremely difficult) uphill battle.
>>
>> If Ambisonics is not included for reasons of laziness, infighting tribes
>> or whatever else, I would say: Game over for Ambisonics in the
>> real-world.... (I don't mean this in a rude way. The thing is just that
>> the MPEG won't wait for even the most beautiful HOA standard which will be
>> represented in the year 2015 or 2020...)
>>
>> The advantages of Ambisonics are clear: It is by definition a 3D audio
>> theory/codec, and you can decode to different loudpeaker layouts and
>> headphones. (This is of course very basic, but you have to tell this to
>> people if presenting a proposal.)
>>
>>
>> Best regards,
>>
>> Stefan Schreiber Lisbon
>>
>>
>> P.S.: I personally would/will work with any 3D audio standard. Because
>> MPEG-H 3rd part (audio) will be a selection of several codecs/approaches,
>> Ambisonics should be included. If so, I would define two options: some
>> "purist" approach, but also some "B+" approach, which maybe fits more to
>> cinema-audio in the real world.
>>
>> Now Thomas Chen (still lurking on this list?) would probably agree,
>> because the original (6-channel) B+ proposal if from him. Unfortunately he
>> works at Dolby... :-X
>>
>>
>> _______________________________________________
>> Sursound mailing list
>> Sursound@music.vt.edu
>> https://mail.music.vt.edu/mailman/listinfo/sursound
>>
>>
>>
>
>
> -------------- next part --------------
> An HTML attachment was scrubbed...
> URL:
> <https://mail.music.vt.edu/mailman/private/sursound/attachments/20130120/cea64251/attachment.html>
> _______________________________________________
> Sursound mailing list
> Sursound@music.vt.edu
> https://mail.music.vt.edu/mailman/listinfo/sursound
--
As of 1st October 2012, I have retired from the University, so this
disclaimer is redundant....
These are my own views and may or may not be shared by my employer
Dave Malham
Ex-Music Research Centre
Department of Music
The University of York
Heslington
York YO10 5DD
UK
'Ambisonics - Component Imaging for Audio'
_______________________________________________
Sursound mailing list
Sursound@music.vt.edu
https://mail.music.vt.edu/mailman/listinfo/sursound
