On Wed, Feb 29, 2012 at 01:15:40PM +0000, Miguel Negrao wrote: > I’ve been a bit disconnected from the ambisonics world. From my past reading > on this list it is my understanding that there isn’t an explicit formula for > decoding coefficients for non-symmetrical setups. Are there currently > available tools to generate decoding coefficients for non-symmetrical setups > or an iterative algorithm that I could implement on my own ?
Two possible methods have been published. The first is Franz Zotter's work, using an 'almost regular' virtual layout based on t-designs for which a decoder can be designed in closed form. Then the virtual set of speakers is mapped onto the real one using VBAP. As far as I know there is no 'ready to use' toolset for this method. The second is the subject of BLaH paper #4, and is based on using a non-linear optimisation toolset to find a solution, given the error constraints and weights for a set of performance metrics. I developed more or less the same (even using the same freely available non-linear library), but wasn't allowed to publish the results, so I can confirm this can work rather well. What looks like a practical implementation (by B,L & H) of this method is scheduled for presentation at the next Linux Audio Conference at CCRMA. I don't think either method can be used 'blindly', in the sense that you just throw a set of speaker coordinates at it and get a guaranteed result. You will have to evaluate the results, and you may have to decide on tradeoffs and iterate the procedure using modified parameter sets. At this point you will need some familiarity with the internals in order to be able to proceed. Ciao, -- FA Vor uns liegt ein weites Tal, die Sonne scheint - ein Glitzerstrahl. _______________________________________________ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
