On Fri, Jan 25, 2013 at 08:32:57PM +0100, Sven Thebert wrote: > I'm interested in Ambisonics decoding and I have the idea to broadcast > b-format over 802.11g to the speakers. A programmed microcontroller > mounted right behind each speaker will receive the b-format stream > and, by knowing the position of its speaker and the geometric > formation of the array, the µC will solve the ambisonics decoding > matrix and will send the calculated audio to the active speaker. > > Do you think, there is some interest in such a technique?
There is a practical matter to consider. The speakers will need a power cable anyway. So what is gained by transmitting the audio wireless ? 'Distributing' the decoder is an interesting idea, but it doesn't imply a wireless connection. > The main question will be: How can I guarantee that all receiving µCs > work synchronous, or with so little jitter, that the sound image for > the listener doesn't collapse? This will be your main problem. The B-format signals as received by each decoder will be coherent, no problem there. If you use some buffering in each receiver so the signal isn't ever interrupted by random transmission delays there won't be any jitter, but there will be some more or less random delay for each speaker. You'd need to keep the delay differences to within at least 0.5 ms or so. This could be quite a challenge. > By using 802.11g, is there enough bandwidth for streaming uncompressed > b-format? Probably yes for first order. > How much DSP power is needed for decoding? Unless you want to add another challenge you should have a DSP that can do floating point. All the required routines are readily available in that case. Recoding them to fixed point while preserving quality won't be trivial. It's made more difficult by the fact that the processing is done after the final volume control and hence requires a very wide dynamic range. For optimal decoding you'd need: - near field compensations filter (easy for low orders) - crossover filters for 2-band decoding, or shelf filters, also these are not really complex, - all the rest is just 'multiply and add'. 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
