On Mon, Sep 15, 2014 at 08:32:24PM +0200, Jörn Nettingsmeier wrote: > There is no established standardized main microphone for Auro 3D. In > fact, practices vary wildly, so that different Auro 3D productions > have totally different degrees of localisation, crosstalk, and > channel decorrelation. This has dramatic effects on up- or > downmixing algorithms, if format conversions are required later in > the production chain.
Which in mnay cases will be near impossible, except maybe by some manually controlled magic and trickery, ad-hoc for each case. > One vocal proponent of Auro 3D as a classical recording format > insists that a huge square of omnis is the only acceptable miking > technique. No comment. The only thing you can hope to do with such a recording is to deliver the signals to the speakers. > The format just defines speaker positions, not signal relationships. As does e.g. 22.2. At least 5.1 had *some* paradigm behind it, or could pretend to have one. That can't be said of any of the 'umpteen speakers' formats. > It is easily possible to create a higher-order recording even > without a native HOA microphone, as long as it's understood that any > ambient microphones are used such that they do not contribute to any > co-incident holophonic image, but just add highly decorrelated > diffuse field information which is to some extent "artificial". In > that sense, they are not "ambisonic", they just use the Ambisonic > format to include some decorrelated ambience with sufficiently low > crosstalk. And that's not really anything new - this has been done for ages with plain old stereo. When going that way - panned discrete sources plus a separately generated diffuse ambience - the AMB format remains the one of choice. At least the one that leaves open lots of ways in wich the result can be modified in useful ways later. I must agree with Stefan's point about 4th order AMB using the Eigenmic or similar. It doesn't make sense at all. We would be much better off with e.g. a second order mic followed by some logic decoding (a Harpex on steroids). I can't help but having the impression that the whole 'spatial HD' audio field is in a state of complete uncontrolled chaos. Just today I was reading the MPEG specs for HOA - if ever any standard bears all the marks of design by committee this one does. It's depressing. Ciao, -- FA A world of exhaustive, reliable metadata would be an utopia. It's also a pipe-dream, founded on self-delusion, nerd hubris and hysterically inflated market opportunities. (Cory Doctorow) _______________________________________________ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound - unsubscribe here, edit account or options, view archives and so on.
