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
