Hello all, and thankyou for your wonderful and informative replies. There is a lot to learn it seems and I will no doubt pose other questions after Ive read more and digested what has already been said. David - 56 channels ! I would have been drowning in a spaghetti of cables and tape I think. I dont know the speakers you speak of but please let me know if you remember what they are called. In regards to the speakers - yes we are looking into buying some tropical proof weather speakers. I believe Eden had some type of all weather speakers before but even they didnt last long. Put it this way - even keeping a mains supply is difficult in the biome - ants chew though everything (literally) and the humidity is fercocious - Ive heard there are some self draining military grade speakers around and any suggestions are appreciated. The thing is even speakers designed for subtropical conditions may not hack it - they really have to be specially designed for really really humid conditions (we can treat them with antiant stuff )
On 26 January 2011 17:00, <sursound-requ...@music.vt.edu> wrote: > Send Sursound mailing list submissions to > sursound@music.vt.edu > > To subscribe or unsubscribe via the World Wide Web, visit > https://mail.music.vt.edu/mailman/listinfo/sursound > or, via email, send a message with subject or body 'help' to > sursound-requ...@music.vt.edu > > You can reach the person managing the list at > sursound-ow...@music.vt.edu > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of Sursound digest..." > > > When replying, please remember to edit your Subject line to that of the > original message you are replying to, so it is more specific than "Re: > Contents of Sirsound-list digest..." > > > Today's Topics: > > 1. Re: Why do you need to decode ambisonic/b format signals > (Geoffrey Barton) > 2. Re: Why do you need to decode ambisonic/b format signals > (Steven Dive) > 3. Subject: Re: Why do you need to decode ambisonic/b format > signals ? (Augustine Leudar) > 4. Re: Subject: Re: Why do you need to decode ambisonic/b format > signals ? (Danny McCarty) > 5. Re: Subject: Re: Why do you need to decode ambisonic/b format > signals ? (Andrew Levine) > 6. Re: Subject: Re: Why do you need to decode ambisonic/b format > signals ? (Eero Aro) > 7. Re: Subject: Re: Why do you need to decode ambisonic/b format > signals ? (Andrew Levine) > 8. Re: Subject: Re: Why do you need to decode ambisonic/b format > signals ? (Dave Malham) > 9. Re: Subject: Re: Why do you need to decode ambisonic/b format > signals ? (Dave Malham) > 10. Re: Why do you need to decode ambisonic/b format signals > (J?rn Nettingsmeier) > 11. Re: Subject: Re: Why do you need to decode ambisonic/b format > signals ? (f...@kokkinizita.net) > 12. Re: Subject: Re: Why do you need to decode ambisonic/b format > signals ? (J?rn Nettingsmeier) > 13. Re: Subject: Re: Why do you need to decode ambisonic/b format > signals ? (Eero Aro) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Tue, 25 Jan 2011 20:53:26 +0000 > From: Geoffrey Barton <geoffreybar...@mac.com> > Subject: Re: [Sursound] Why do you need to decode ambisonic/b format > signals > To: sursound@music.vt.edu > Message-ID: <24877c29-388f-426d-af49-3c1d6c6f9...@mac.com> > Content-Type: text/plain; charset="us-ascii" > > > On 25 Jan 2011, at 17:00, sursound-requ...@music.vt.edu wrote: > > > > Message: 8 > > Date: Mon, 24 Jan 2011 12:03:11 -0700 > > From: Martin Leese <martin.le...@stanfordalumni.org> > > Subject: Re: [Sursound] Why do you need to decode ambisonic/b format > > signals ? > > To: sursound@music.vt.edu > > Message-ID: > > <aanlktintvfioetlvgaok3gx7pbx8k0uq5opr30eyh...@mail.gmail.com> > > Content-Type: text/plain; charset=ISO-8859-1 > > > > Eero Aro <eero....@dlc.fi> wrote: > > > >> J?rn Nettingsmeier wrote: > >>> in theory, you can. in practice, you can't, because you'd have to know > >>> what stereo technique was used during recording > >> > >> Yes you can. > >> > >> Just one word: Trifield. > > > > Steven Dive <stevend...@mac.com> wrote: > > ... > >> I understand that Trifield is derived from the same groundwork as > >> Ambisonic, which also gives us ambi superstereo. It's a matter of > >> personal judgement, I think, but do you more knowledgeable theory > >> folks know if Trifield is therefore as flexible in its use as > >> superstereo? > > > >> From memory, the theory behind Trifield > > assumes either Blumlein XY, or pan-potted > > multi-track mono. Perhaps Geoffrey can chip > > in, or somebody can look at the paper > > (reference below). Again from memory, > > SuperStereo assumes some sort of coincident > > mic technique so, in theory, is more flexible > > than Trifield. I don't know of a reference for > > SuperStereo; this is a gap in Ambisonic > > theory. > > It is not essential that the material is Blumlein or pan potted; that is > just the way MAG handled a virtual 'test signal' in the paper; other > recording techniques work ok too, but with varying results, much as they do > over two speakers:-). > > The main difference between 'Trifield' and 'Super-stereo' is that the > former works over a number of speakers >2 across the front sector and the > latter seeks to use an ambisonic array of speakers all around the listener > to lock the front in place. There were a number of different alignments of > 'Super-stereo' in various decoder implementations, but in essence they all > sought to bend the 'washing line' of the in-phase stereo image around the > front arc with variable width, and anything substantially out of phase > generally somewhere else, again rather dependent on the source material. > > Geoffrey > > > > > > > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: < > https://mail.music.vt.edu/mailman/private/sursound/attachments/20110125/52e2d5cc/attachment.html > > > > > ------------------------------ > > Message: 2 > Date: Tue, 25 Jan 2011 22:11:38 +0000 > From: Steven Dive <stevend...@mac.com> > Subject: Re: [Sursound] Why do you need to decode ambisonic/b format > signals > To: Surround Sound discussion group <sursound@music.vt.edu> > Message-ID: <34cb10b0-dbea-4897-a418-8d90906d0...@mac.com> > Content-Type: text/plain; CHARSET=US-ASCII; format=flowed; delsp=yes > > One interesting, if odd sounding, effect I found was using superstereo > on a test track for channel identity for stereo that had someone (Alan > Wiltshire) speaking from positions full left, half left, centre, half > right and full right. On my usual setting of 0.5 (range is 0 to 1.5 on > my decoder in 0.1 increments)), the speaking positions are perceived > pretty near corresponding to the left to right spacing of my front > speakers. On the 1.0 setting, the image of full left to full right is > wrapped around like a horseshoe, with left as rear left and right as > rear right with centre and 'half' positions stretched around > accordingly and somewhat broadened. But on the full 1.5 setting the > apparent speaking positions were fully reversed, with right as left > and left as right but sounding really quite focussed. > > Any thoughts welcome. It darn well surprised me. > > Steve > > On 25 Jan 2011, at 20:53, Geoffrey Barton wrote: > > > > > On 25 Jan 2011, at 17:00, sursound-requ...@music.vt.edu wrote: > >> > >> Message: 8 > >> Date: Mon, 24 Jan 2011 12:03:11 -0700 > >> From: Martin Leese <martin.le...@stanfordalumni.org> > >> Subject: Re: [Sursound] Why do you need to decode ambisonic/b format > >> signals ? > >> To: sursound@music.vt.edu > >> Message-ID: > >> <aanlktintvfioetlvgaok3gx7pbx8k0uq5opr30eyh...@mail.gmail.com> > >> Content-Type: text/plain; charset=ISO-8859-1 > >> > >> Eero Aro <eero....@dlc.fi> wrote: > >> > >>> J?rn Nettingsmeier wrote: > >>>> in theory, you can. in practice, you can't, because you'd have to > >>>> know > >>>> what stereo technique was used during recording > >>> > >>> Yes you can. > >>> > >>> Just one word: Trifield. > >> > >> Steven Dive <stevend...@mac.com> wrote: > >> ... > >>> I understand that Trifield is derived from the same groundwork as > >>> Ambisonic, which also gives us ambi superstereo. It's a matter of > >>> personal judgement, I think, but do you more knowledgeable theory > >>> folks know if Trifield is therefore as flexible in its use as > >>> superstereo? > >> > >>> From memory, the theory behind Trifield > >> assumes either Blumlein XY, or pan-potted > >> multi-track mono. Perhaps Geoffrey can chip > >> in, or somebody can look at the paper > >> (reference below). Again from memory, > >> SuperStereo assumes some sort of coincident > >> mic technique so, in theory, is more flexible > >> than Trifield. I don't know of a reference for > >> SuperStereo; this is a gap in Ambisonic > >> theory. > > > > It is not essential that the material is Blumlein or pan potted; > > that is just the way MAG handled a virtual 'test signal' in the > > paper; other recording techniques work ok too, but with varying > > results, much as they do over two speakers:-). > > > > The main difference between 'Trifield' and 'Super-stereo' is that > > the former works over a number of speakers >2 across the front > > sector and the latter seeks to use an ambisonic array of speakers > > all around the listener to lock the front in place. There were a > > number of different alignments of 'Super-stereo' in various decoder > > implementations, but in essence they all sought to bend the 'washing > > line' of the in-phase stereo image around the front arc with > > variable width, and anything substantially out of phase generally > > somewhere else, again rather dependent on the source material. > > > > Geoffrey > > > > > > > > > > > > > > -------------- next part -------------- > > An HTML attachment was scrubbed... > > URL: < > https://mail.music.vt.edu/mailman/private/sursound/attachments/20110125/52e2d5cc/attachment.html > > > > > _______________________________________________ > > Sursound mailing list > > Sursound@music.vt.edu > > https://mail.music.vt.edu/mailman/listinfo/sursound > > > > ------------------------------ > > Message: 3 > Date: Wed, 26 Jan 2011 05:33:05 +0000 > From: Augustine Leudar <gustar...@gmail.com> > Subject: [Sursound] Subject: Re: Why do you need to decode ambisonic/b > format signals ? > To: sursound@music.vt.edu > Message-ID: > <aanlktimmzeg4uo_djw55n-pxkredey6oeds7ercew...@mail.gmail.com> > Content-Type: text/plain; charset="iso-8859-1" > > Message: 6 > Date: Sat, 22 Jan 2011 23:56:42 +0100 > From: f...@kokkinizita.net > Subject: Re: [Sursound] Why do you need to decode ambisonic/b format > > > First, don't try and send HTML to this list, as you can see it will > be removed. > > Sorry - I dont know what you mean - as far as Iknow I haven't sent any > html to this list (at least not intentionally) - I assume you don't mean > links as there was no link in my original message and > there are also many links in the messages on this list. > > > Your question reveals that you have not even started to study and > > understand Ambisonics theory - the answer would be quite evident > > in the other case > > > > Obviously - or I wouldnt be asking how it works..... I do however have a > lot of experience creating 3d soundscapes (in fact its my job) and have > spent a reasonable amount of time studying a wide range of psychoacoustic > topics and other areas pertaining to sound art. Now Ive read a bit more it > is certainly something I will be persuing. > > > . You could as well ask a engineer why he needs > > complex numbers while you can do your bookkeeping without. > > > > Engineers ? bookeeping ? I think I know what you mean. > > Hoping you will eventually have a go at it, > > > > I will absolutely be having a go at it - the replies I received here has > led me to a flurry of reading - the result is I am now utterly intrigued > by > ambisonics and cant wait to try it out the more I read the more I get > sucked > in - I even found myself trying to unravel the maths last night - that > might > take a while...) . I only got so far but as I understand it it uses sound > pressure levels and phase differences to plot x,y,z spherical coordinates > which are then reconstituted in the decoding - out of curiosity Why the > need > for the w coordinate - cant the sound pressure level be gleaned from the > x,y > and z ? At the moment the soundscapes I am working on are large jungle > soundscapes in a large indoor tropical conservatory ( covering several > acres) - perhaps with twenty metres between speakers. Because of the > problems of amplitude panning and the sheer size of the installations often > sounds are localised by using real world object analogues (ie if a monkey > is > meant to sound like it comes from behind a certain tree there is a speaker > with a monkey noise behind that tree)a thunderstorm is represented by a > stereo pair high on a hillside - we even had neighbours thinking there was > real thunderstorm happening and it does sound well, realistic (don't take > my > word for it you can read the public response here : > http://augustineleudar.110mb.com/Hd/Hod.html ) . This type of localisation > has proved extremely effective and don't think that any system no matter > how > clever at fooling the human ear can improve upon a sound actually coming > from the direction its meant to (though recording ambisonically probably > would) . Where ambisonics could help in the installation is the insect > noises - at the moment there are large 4 speaker areas with 4mic recorded > insect noises . Gaps in the image are plugged with other speakers with say > cicadas on them - despite the doubts expressed here it also has been > effective perhaps because insect noises are high frequency and the leaves > on the bushes and trees disperse the sound filling out the sound field. > Generally the effect is pretty similar to being in the rain forest- except > you don't get bitten. However if what I have read about ambisonics is true > it would make it sound even better and there is always room for improvement > . I am currently trying to translate some of these sound installations to > a > format that can be listened to at home - I have to admit 5.1 is a bit > frustrating so ambisonics might hold the key. What I would like to know is > can the decoding be done with software and then burnt to wav files ? There > is no way a physical decoder could be in the biome - we generally have to > throw speakers away or sell them on ebay after a few uses because of the > ants and humidity (wav players are in sealed plastic boxes) . Are there > any ambisonic panners that are VST compatible (I mainly use Nuendo and MAx > MSP) ? Could I design a horizontal surround sound DVD using ambisonic > software for panning and localisation - and then burn 6 wav files and > release it on a 5.1 DVD which could be played on a normal home system ? > best, > Gus > > > >> -- > FA > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: < > https://mail.music.vt.edu/mailman/private/sursound/attachments/20110126/b08d7757/attachment.html > > > > > ------------------------------ > > Message: 4 > Date: Tue, 25 Jan 2011 21:56:21 -0800 > From: Danny McCarty <d...@monolithmedia.net> > Subject: Re: [Sursound] Subject: Re: Why do you need to decode > ambisonic/b format signals ? > To: Surround Sound discussion group <sursound@music.vt.edu> > Message-ID: <c5fd334e-a7e5-4f43-8010-d5c2e8eb8...@monolithmedia.net> > Content-Type: text/plain; charset=us-ascii > > Nice response Gus and certainly more gracious than I would have been. > Danny > > > > On Jan 25, 2011, at 9:33 PM, Augustine Leudar wrote: > > > Message: 6 > > Date: Sat, 22 Jan 2011 23:56:42 +0100 > > From: f...@kokkinizita.net > > Subject: Re: [Sursound] Why do you need to decode ambisonic/b format > > > > > > First, don't try and send HTML to this list, as you can see it will > > be removed. > > > > Sorry - I dont know what you mean - as far as Iknow I haven't sent any > > html to this list (at least not intentionally) - I assume you don't mean > > links as there was no link in my original message and > > there are also many links in the messages on this list. > > > > > > Your question reveals that you have not even started to study and > >> understand Ambisonics theory - the answer would be quite evident > >> in the other case > >> > > > > Obviously - or I wouldnt be asking how it works..... I do however have a > > lot of experience creating 3d soundscapes (in fact its my job) and have > > spent a reasonable amount of time studying a wide range of psychoacoustic > > topics and other areas pertaining to sound art. Now Ive read a bit more > it > > is certainly something I will be persuing. > > > > > > . You could as well ask a engineer why he needs > >> complex numbers while you can do your bookkeeping without. > >> > > > > Engineers ? bookeeping ? I think I know what you mean. > > > > Hoping you will eventually have a go at it, > >> > > > > I will absolutely be having a go at it - the replies I received here > has > > led me to a flurry of reading - the result is I am now utterly intrigued > by > > ambisonics and cant wait to try it out the more I read the more I get > sucked > > in - I even found myself trying to unravel the maths last night - that > might > > take a while...) . I only got so far but as I understand it it uses > sound > > pressure levels and phase differences to plot x,y,z spherical coordinates > > which are then reconstituted in the decoding - out of curiosity Why the > need > > for the w coordinate - cant the sound pressure level be gleaned from the > x,y > > and z ? At the moment the soundscapes I am working on are large jungle > > soundscapes in a large indoor tropical conservatory ( covering several > > acres) - perhaps with twenty metres between speakers. Because of the > > problems of amplitude panning and the sheer size of the installations > often > > sounds are localised by using real world object analogues (ie if a monkey > is > > meant to sound like it comes from behind a certain tree there is a > speaker > > with a monkey noise behind that tree)a thunderstorm is represented by a > > stereo pair high on a hillside - we even had neighbours thinking there > was > > real thunderstorm happening and it does sound well, realistic (don't take > my > > word for it you can read the public response here : > > http://augustineleudar.110mb.com/Hd/Hod.html ) . This type of > localisation > > has proved extremely effective and don't think that any system no matter > how > > clever at fooling the human ear can improve upon a sound actually coming > > from the direction its meant to (though recording ambisonically probably > > would) . Where ambisonics could help in the installation is the insect > > noises - at the moment there are large 4 speaker areas with 4mic recorded > > insect noises . Gaps in the image are plugged with other speakers with > say > > cicadas on them - despite the doubts expressed here it also has been > > effective perhaps because insect noises are high frequency and the > leaves > > on the bushes and trees disperse the sound filling out the sound field. > > Generally the effect is pretty similar to being in the rain forest- > except > > you don't get bitten. However if what I have read about ambisonics is > true > > it would make it sound even better and there is always room for > improvement > > . I am currently trying to translate some of these sound installations > to a > > format that can be listened to at home - I have to admit 5.1 is a bit > > frustrating so ambisonics might hold the key. What I would like to know > is > > can the decoding be done with software and then burnt to wav files ? > There > > is no way a physical decoder could be in the biome - we generally have to > > throw speakers away or sell them on ebay after a few uses because of the > > ants and humidity (wav players are in sealed plastic boxes) . Are there > > any ambisonic panners that are VST compatible (I mainly use Nuendo and > MAx > > MSP) ? Could I design a horizontal surround sound DVD using ambisonic > > software for panning and localisation - and then burn 6 wav files and > > release it on a 5.1 DVD which could be played on a normal home system ? > > best, > > Gus > > > > > >>> -- > > FA > > -------------- next part -------------- > > An HTML attachment was scrubbed... > > URL: < > https://mail.music.vt.edu/mailman/private/sursound/attachments/20110126/b08d7757/attachment.html > > > > _______________________________________________ > > Sursound mailing list > > Sursound@music.vt.edu > > https://mail.music.vt.edu/mailman/listinfo/sursound > > Danny McCarty > Monolith Media, Inc. > 4183 Summit View > Hood River, Or 97031 > > 415-331-7628 > 541-399-0089 Cell > > http://www.monolithmedia.net/ > > http://www.danielmccarty.com/ > > > > > > > > > > > > > > > > > ------------------------------ > > Message: 5 > Date: Wed, 26 Jan 2011 07:36:17 +0100 > From: Andrew Levine <andrew.lev...@blumlein.net> > Subject: Re: [Sursound] Subject: Re: Why do you need to decode > ambisonic/b format signals ? > To: Surround Sound discussion group <sursound@music.vt.edu> > Message-ID: <93a9b7bd-bd59-452b-91e1-2fee53cb8...@blumlein.net> > Content-Type: text/plain; charset=us-ascii > > Hi Augustine, > > On 26.01.2011, at 06:33, Augustine Leudar wrote: > > I am now utterly intrigued by > > ambisonics and cant wait to try it out the more I read the more I get > sucked > > in > > I know what you're talking about :-) > > > Gaps in the image are plugged with other speakers with say > > cicadas on them - despite the doubts expressed here it also has been > > effective perhaps because insect noises are high frequency and the > leaves > > on the bushes and trees disperse the sound filling out the sound field. > > Generally the effect is pretty similar to being in the rain forest- > except > > you don't get bitten. > > I didn't know cicadas bit ;-) > > > What I would like to know is > > can the decoding be done with software and then burnt to wav files ? > > Sure. This is what some call G-format. > > > Are there > > any ambisonic panners that are VST compatible (I mainly use Nuendo and > MAx > > MSP) ? Could I design a horizontal surround sound DVD using ambisonic > > software for panning and localisation - and then burn 6 wav files and > > release it on a 5.1 DVD which could be played on a normal home system ? > > So far I haved worked with plugins by Bruce Wiggins ( > http://www.brucewiggins.co.uk/?page_id=78) and Daniel Courville ( > http://www.radio.uqam.ca/ambisonic/b2x.html). > > Regards, > > Andrew > > ------------------------------ > > Message: 6 > Date: Wed, 26 Jan 2011 09:56:10 +0200 > From: Eero Aro <eero....@dlc.fi> > Subject: Re: [Sursound] Subject: Re: Why do you need to decode > ambisonic/b format signals ? > To: sursound@music.vt.edu > Message-ID: <4d3fd39a.4090...@dlc.fi> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > Augustine Leudar wrote: > > Why the need for the w coordinate > > I am not a mathematician or a scientist. A sound designer's reply: > The W is a "reference" signal. For example, at decoding: > + W + X is the "front" direction (W and X at equal phase) > + W - X is the "rear" direction (X phase reversed in relation to W) > > Try to look at 1st order B-Format (WXYZ) as a "three dimensional > MS-stereo signal". That helped me in the beginning. > > > the soundscapes I am working on are large jungle > > soundscapes in a large indoor tropical conservatory > > You must have looked at Timax? > http://www.outboard.co.uk/pages/timax.htm > > > Where ambisonics could help in the installation is the insect > > noises > > Yep. A single mono sound is best localized to all listeners when you > play it back through one speaker only. It is a good idea to route that > kind of signals directly into the appropriate speaker. A combination of > different techniques is possibly the best way to do it. Soundfields with > moving phantom images and ambiences and spatial images are easy > to control with B-Format Ambisonics. As somebody already said, it is > possible to rotate, tilt and tumble a full 3D soundfield, and much more. > You can for example "zoom in" into a certain direction. > > > can the decoding be done with software and then burnt to wav files ? > > Andrew gave you good pointers. Bruce Wiggins has described workflows > in his page. Possibly you'd like to check also these sites: > > Dave Malham: > http://www.dmalham.freeserve.co.uk/vst_ambisonics.html > http://www.york.ac.uk/inst/mustech/3d_audio/vst/welcome.html > > Visual Virtual Mic: > http://mcgriffy.com/audio/ambisonic/vvmic/ > > Aristotel Digenis: > http://www.digenis.co.uk/ > > Acousmodules. No Ambisonics in there, but you might find other useful > tools: > http://acousmodules.free.fr/acousmodules_en.htm > > Eero > > > ------------------------------ > > Message: 7 > Date: Wed, 26 Jan 2011 09:06:41 +0100 > From: Andrew Levine <andrew.lev...@blumlein.net> > Subject: Re: [Sursound] Subject: Re: Why do you need to decode > ambisonic/b format signals ? > To: Surround Sound discussion group <sursound@music.vt.edu> > Message-ID: <7cd48a0c-ba64-47ce-9395-b4b2222f6...@blumlein.net> > Content-Type: text/plain; charset=us-ascii > > On 26.01.2011, at 08:56, Eero Aro wrote: > > Dave Malham: > > http://www.dmalham.freeserve.co.uk/vst_ambisonics.html > > http://www.york.ac.uk/inst/mustech/3d_audio/vst/welcome.html > > these have not worked for me on a Mac runnig OSX 10.6. > > Cheers, > > Andrew > > > ------------------------------ > > Message: 8 > Date: Wed, 26 Jan 2011 08:58:46 +0000 > From: Dave Malham <dave.mal...@york.ac.uk> > Subject: Re: [Sursound] Subject: Re: Why do you need to decode > ambisonic/b format signals ? > To: Surround Sound discussion group <sursound@music.vt.edu> > Message-ID: <4d3fe246.5090...@york.ac.uk> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > Oops - I'll check the versions! I certainly run the current ones we use > here on 10.6 and I thought > the ones on the web were able to, too. Sorry folks. > > Dave > > On 26/01/2011 08:06, Andrew Levine wrote: > > On 26.01.2011, at 08:56, Eero Aro wrote: > >> Dave Malham: > >> http://www.dmalham.freeserve.co.uk/vst_ambisonics.html > >> http://www.york.ac.uk/inst/mustech/3d_audio/vst/welcome.html > > these have not worked for me on a Mac runnig OSX 10.6. > > > > Cheers, > > > > Andrew > > _______________________________________________ > > Sursound mailing list > > Sursound@music.vt.edu > > https://mail.music.vt.edu/mailman/listinfo/sursound > > -- > These are my own views and may or may not be shared by my employer > /*********************************************************************/ > /* Dave Malham http://music.york.ac.uk/staff/research/dave-malham/ */ > /* Music Research Centre */ > /* Department of Music "http://music.york.ac.uk/"; */ > /* The University of York Phone 01904 432448 */ > /* Heslington Fax 01904 432450 */ > /* York YO10 5DD */ > /* UK 'Ambisonics - Component Imaging for Audio' */ > /* "http://www.york.ac.uk/inst/mustech/3d_audio/"; */ > /*********************************************************************/ > > > > ------------------------------ > > Message: 9 > Date: Wed, 26 Jan 2011 09:12:22 +0000 > From: Dave Malham <dave.mal...@york.ac.uk> > Subject: Re: [Sursound] Subject: Re: Why do you need to decode > ambisonic/b format signals ? > To: Surround Sound discussion group <sursound@music.vt.edu> > Message-ID: <4d3fe576.40...@york.ac.uk> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > > > On 26/01/2011 05:33, Augustine Leudar wrote: > > > > Because of the > > problems of amplitude panning and the sheer size of the installations > often > > sounds are localised by using real world object analogues (ie if a monkey > is > > meant to sound like it comes from behind a certain tree there is a > speaker > > with a monkey noise behind that tree)a thunderstorm is represented by a > > stereo pair high on a hillside - we even had neighbours thinking there > was > > real thunderstorm happening and it does sound well, realistic (don't take > my > > word for it you can read the public response here : > > http://augustineleudar.110mb.com/Hd/Hod.html ) . This type of > localisation > > has proved extremely effective and don't think that any system no matter > how > > clever at fooling the human ear can improve upon a sound actually coming > > from the direction its meant to (though recording ambisonically probably > > would) > Absolutely true - Ambisonics is not the answer to life, the universe and > everything! (but it comes > close in some areas). It was for exactly the reasons you give above that > when we did the original > soundscapes for the Yorvik Viking Centre ( > http://www.jorvik-viking-centre.co.uk/) way back in the > early 80's we chose to go with 56 tracks of audio (on McKenzie 4 track 1/4" > continuous loop analogue > tape!) going through even more speakers, rather than using Ambisonics - and > Yorvik is a much smaller > area! BTW, have you seen those tiny speakers that fir into a standard > electrical socket back box > (and hence are almost invisible)? I was most impressed with them when I > visited an exhibition of > South African sculpture in Madeira this summer...trouble is, I can't > remember who made them :-( > > > . Where ambisonics could help in the installation is the insect > > noises - at the moment there are large 4 speaker areas with 4mic recorded > > insect noises . Gaps in the image are plugged with other speakers with > say > > cicadas on them - despite the doubts expressed here it also has been > > effective perhaps because insect noises are high frequency and the > leaves > > on the bushes and trees disperse the sound filling out the sound field. > > Generally the effect is pretty similar to being in the rain forest- > except > > you don't get bitten. However if what I have read about ambisonics is > true > > it would make it sound even better and there is always room for > improvement > > . > Certainly worth trying > > > I am currently trying to translate some of these sound installations to > a > > format that can be listened to at home - I have to admit 5.1 is a bit > > frustrating so ambisonics might hold the key. What I would like to know > is > > can the decoding be done with software and then burnt to wav files ? > There > > is no way a physical decoder could be in the biome - we generally have to > > throw speakers away or sell them on ebay after a few uses because of the > > ants and humidity (wav players are in sealed plastic boxes) . Are there > > any ambisonic panners that are VST compatible (I mainly use Nuendo and > MAx > > MSP) ? Could I design a horizontal surround sound DVD using ambisonic > > software for panning and localisation - and then burn 6 wav files and > > release it on a 5.1 DVD which could be played on a normal home system ? > > best, > > Gus > > > This is definitely where Ambisonics would shine, I feel , though the use of > G format, as others have > said - or even UHJ > > > Dave > > -- > These are my own views and may or may not be shared by my employer > /*********************************************************************/ > /* Dave Malham http://music.york.ac.uk/staff/research/dave-malham/ */ > /* Music Research Centre */ > /* Department of Music "http://music.york.ac.uk/"; */ > /* The University of York Phone 01904 322448 */ > /* Heslington Fax 01904 322450 */ > /* York YO10 5DD */ > /* UK 'Ambisonics - Component Imaging for Audio' */ > /* "http://www.york.ac.uk/inst/mustech/3d_audio/"; */ > /*********************************************************************/ > > > > ------------------------------ > > Message: 10 > Date: Wed, 26 Jan 2011 12:10:24 +0100 > From: J?rn Nettingsmeier <netti...@stackingdwarves.net> > Subject: Re: [Sursound] Why do you need to decode ambisonic/b format > signals > To: sursound@music.vt.edu > Message-ID: <4d400120.7020...@stackingdwarves.net> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > On 01/25/2011 09:53 PM, Geoffrey Barton wrote: > > > >> Martin Leese<martin.le...@stanfordalumni.org>: > >>> J?rn Nettingsmeier wrote: > >>>> in theory, you can. in practice, you can't, because you'd have > >>>> to know what stereo technique was used during recording > >>> > >>> Yes you can. > >>> Just one word: Trifield. > > > > It is not essential that the material is Blumlein or pan potted; > > that is just the way MAG handled a virtual 'test signal' in the > > paper; other recording techniques work ok too, but with varying > > results, much as they do over two speakers:-). > > that's a solomonic verdict i can live with :) > > > > -- > J?rn Nettingsmeier > Lortzingstr. 11, 45128 Essen, Tel. +49 177 7937487 > > Meister f?r Veranstaltungstechnik (B?hne/Studio), Elektrofachkraft > Audio and event engineer - Ambisonic surround recordings > > http://stackingdwarves.net > > > > ------------------------------ > > Message: 11 > Date: Wed, 26 Jan 2011 12:17:57 +0100 > From: f...@kokkinizita.net > Subject: Re: [Sursound] Subject: Re: Why do you need to decode > ambisonic/b format signals ? > To: sursound@music.vt.edu > Message-ID: <20110126111757.GA3917@zita2> > Content-Type: text/plain; charset=us-ascii > > On Wed, Jan 26, 2011 at 05:33:05AM +0000, Augustine Leudar wrote: > > > First, don't try and send HTML to this list, as you can see it will > > be removed. > > > > Sorry - I dont know what you mean - as far as Iknow I haven't sent any > > html to this list (at least not intentionally) - I assume you don't mean > > links as there was no link in my original message and > > there are also many links in the messages on this list. > > No, links are perfectly OK. But your messages (as they arrive > to readers of the list) end like this: > > An HTML attachment was scrubbed... > URL: < > https://mail.music.vt.edu/mailman/private/sursound/attachments/20110126/b08d7757/attachment.html > > > > which means your mail program is sending an HTML copy of your > text as well. Most mailing lists have a 'no HTML' policy, and > some, like this one, will actually remove it. > > > I only got so far but as I understand it it uses sound > > pressure levels and phase differences to plot x,y,z spherical coordinates > > which are then reconstituted in the decoding - out of curiosity Why the > need > > for the w coordinate - cant the sound pressure level be gleaned from the > x,y > > and z ? > > If they were just coordinates then you could find w from x,y,z. > But they are something different. > > Image the sound field created by some source, e.g. a sine wave > reproduced by a speaker. At each point in space there two physical > quantities involved: > > * The pressure is going up and down at the frequency of the signal. > This the W signal, which will be produced by an omnidirectional > microphone. > * To make the pressure variations possible at all, some air must move. > Image a tiny volume of air around some point. It will be moving > back and forth. The velocity of this movement is a sine wave, and it > will (in normal cases) be in phase with the pressure signal. But it > also has a *direction* - it is a vector in 3-D space. So it can be > split as the sum of three components along some chosen x,y,z axes. > These components are the X,Y,Z signals. A figure-of-8 microphone > produces a signal equal to the projection of the velocity vector > on its (the microphone's) axis. Three of them are required to have > the full vector. > > For a single source at sufficient distance, the magnitude of the > velocity is proportional to the pressure, they are in phase, and > the direction of the velocity points towards the source. Pressure > and velocity are closely related in that case, but even then you > can't find W from X,Y,Z alone. The reason is that if you put the > source in the exactly opposite direction, and invert its phase, > then it will produce exactly the same X,Y,Z - the inversion of > the signal and the direction cancel each other. So you need W > (which will be inverted) as a phase reference. > > In the more general case, pressure and velocity are independent. > If you have the same signal reproduced by different sources > (or just a single source and a reflection on a wall) you get > standing waves, and there will be points were the pressures > cancel but velocity does not and vice versa. > > Now pressure and velocity are the only two physical quantities > that define a sound field. The basic idea of Ambisonics is that > if you can somehow reconstruct them at the listener's position, > the the listener must hear the same thing as for the real source. > > First order Ambisonics (the version using only W,X,Y,Z) can do > this in a small area, where 'small' is expressed in wavelengths. > So this area is large for low frequencies and gets smaller as > frequency goes up. Above a few hundred Hz it has become so small > that it is even too small for single listener. So for mid and > high frequencies, Ambisonics will use a different strategy which > is based on psychoacoustics. For installations where the listening > area has to be much larger, the 'psychoacoustic' strategy is > normally used at all frequencies. > > Higher order Ambisonics (using more signals) can reconstruct the > sound field in a larger area. It still needs the psychoacoustic > approach for all but the LF range, but this improves as well as > order goes up. At third order and above it becomes very close to > VBAP in fact, with only the speakers nearest to a source direction > contributing in any significant way. The difference with VBAP is > that Ambisonics will not treat the directions corresponding to > the speakers as 'special'. This helps to conceal the speakers > being the source of the reproduced sound. > > Ciao, > > -- > FA > > There are three of them, and Alleline. > > > > ------------------------------ > > Message: 12 > Date: Wed, 26 Jan 2011 12:47:15 +0100 > From: J?rn Nettingsmeier <netti...@stackingdwarves.net> > Subject: Re: [Sursound] Subject: Re: Why do you need to decode > ambisonic/b format signals ? > To: sursound@music.vt.edu > Message-ID: <4d4009c3.9090...@stackingdwarves.net> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > On 01/26/2011 06:33 AM, Augustine Leudar wrote: > > out of curiosity Why the need > > for the w coordinate - cant the sound pressure level be gleaned from the > x,y > > and z ? > > you can't deduce w from figures-of-eight, because they simply don't move > when the pressure rises uniformly (and if they do, that's an artefact of > capsule diameter vs. wavelength and not something we could use). > if the fig8s you've worked with are the double-diaphragm, switchable > pattern type: of course you could take both diaphragms and add them > in-phase, and that would work, because you fake a velocity transducer > with two at least partly pressure-sensitive ones. but that's cheating > and doesn't change the fact that xyz and w are totally independent. > > w is important as a phase reference: without w, you couldn't say from > where the signal in x, y, or z was coming, because your ears can't > detect absolute polarity... > try taking away the centre mic from an m/s pair, and just listen to L=s > and R=-s. no localisation at all. > > > This type of localisation > > has proved extremely effective and don't think that any system no matter > how > > clever at fooling the human ear can improve upon a sound actually coming > > from the direction its meant to > > absolutely. this approach is perfect if your sound event is a point > source, and all you want is the direct sound. if you have wider sources, > or you need to convey ambience, reverb, reflections, it doesn't work so > well, but that's not an objective here iiuc. > > > Where ambisonics could help in the installation is the insect > > noises - at the moment there are large 4 speaker areas with 4mic recorded > > insect noises . Gaps in the image are plugged with other speakers with > say > > cicadas on them - despite the doubts expressed here it also has been > > effective perhaps because insect noises are high frequency and the > leaves > > on the bushes and trees disperse the sound filling out the sound field. > > Generally the effect is pretty similar to being in the rain forest- > except > > you don't get bitten. > > recording insects with a soundfield will probably yield even better > results. > > you could also use "cheat wave field synthesis" if you can place > speakers every meter or so. i heard iosono present such a system at > TMT2010, and they did focused sources (!) :-o > at this speaker distance, spatial aliasing will be terrible, but their > sound example was, brace yourselves: rain. presto. virtual sources all > over the place. should work with insects beautifully, although calling > it wfs might be slightly questionable. > > for fairness, i should say that ambi is just as bad in reproducing > insect or rain noises, but the artefacts (ambiguity, jumpy localisation, > coloration, phasiness) are generally beneficial, as they increase the > "density" and "buzz" of the rain, insect swarm, whatever. > so unless you want your listeners to be able to track the queen bee in > the swarm, you should be fine. > > > There > > is no way a physical decoder could be in the biome - we generally have to > > throw speakers away or sell them on ebay after a few uses because of the > > ants and humidity (wav players are in sealed plastic boxes). > > i don't understand this. are you perhaps using paper membranes? it > should be possible to obtain outdoor speakers that withstand these > conditions for years. of course they will cost a lot more, but that > should be negligible if you have to replace your current speakers that > often... > what do the ants do to the speakers, btw? > > for purely technical reasons you should probably go for 70 or 100v > versions, as i expect your speaker lines to be loooong. the problem is > that 70/100 amplifiers are meant to drive many speakers in parallel, > not many channels discretely, so the price per amp channel might be > prohibitive. but it does give you the option to run the amps and players > outside of the habitat, in conditions appropriate to semiconductors. > > > > -- > J?rn Nettingsmeier > Lortzingstr. 11, 45128 Essen, Tel. +49 177 7937487 > > Meister f?r Veranstaltungstechnik (B?hne/Studio), Elektrofachkraft > Audio and event engineer - Ambisonic surround recordings > > http://stackingdwarves.net > > > > ------------------------------ > > Message: 13 > Date: Wed, 26 Jan 2011 18:02:02 +0200 > From: Eero Aro <eero....@dlc.fi> > Subject: Re: [Sursound] Subject: Re: Why do you need to decode > ambisonic/b format signals ? > To: sursound@music.vt.edu > Message-ID: <4d40457a.90...@dlc.fi> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > J?rn Nettingsmeier wrote: > > recording insects with a soundfield will probably yield even better > > results. > > Been there, done that. As many insect and nature sounds, such as cicadas, > mosquitos, rain, wind etc. are "noise type" sounds, they don't include > point sources that localize sharply to any direction. > > A Soundfield recording of mosquitos sounds good, but in fact you get almost > the same impression by using for example two stereo recordings of > the same type of material. I have noticed that if you spread a stereo > signal > into the Ambisonic soundfield by panning L and R directly to West > and East, you lose all directivity. A better solution is to pan one stereo > pair for example into 40 and 320 degrees and another to 150 and 210. > This is what you do in 5.1 mixing, eh? But with B-format you have the > possibility to tweak that soundfield even more. > > You often hear the cicadas "sing" in "waves". The insects in certain > directions are louder at one moment, then fade and others in other > directions fade up at the same time. That is something that might be > good to record with the Soundfield. > > > it > > should be possible to obtain outdoor speakers that withstand these > > conditions for years. of course they will cost a lot more > > I have good experiences of the JBL Control 1 AW model, "All Weather". > Is it too small for your use, Gus? Control 1 makes a mighty loud noise, > even though it is small in size. We once had eight of them in a periphonic > cube outdoors in the Finnish climate in December (rain, snow, slash, zero > degrees, -28 C degrees, then plus degrees and over again from the start) > playing continously for four weeks 12 hours every day. All worked > fine all the time. When we took the installation down, I had to hit two > of the > speakers hard with my fist so that I could break the ice that had formed > around the speaker. Anyway, the speaker was playing back fine. > > Another type of speakers I have used in outdoor installation, are speakers > that have been designed for boats. They are full plastic and tolerate even > sea water. A set of 16 ran a month in an installation in a park in the > summer of 2009. I think they were LTC speakers. > > Eero > > > ------------------------------ > > _______________________________________________ > Sursound mailing list > Sursound@music.vt.edu > https://mail.music.vt.edu/mailman/listinfo/sursound > > > End of Sursound Digest, Vol 30, Issue 20 > **************************************** > -- 07812675974 -------------- next part -------------- An HTML attachment was scrubbed... URL: <https://mail.music.vt.edu/mailman/private/sursound/attachments/20110126/8b289d29/attachment.html> _______________________________________________ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
