On Sun, 8 Nov 2009 16:53:31 +0100 (CET) karl@xxxxxxxxxxx (Karl Hammar) wrote: > Folderol: > ... > > I started looking at the USB2 protocols for something else, but gave up > > when I saw how insanely complex it is even for relatively simple data > > transfer. In the end, for my project, it was easier to convert the data > > into an RS232 serial stream then use one of the standard serial-USB > > converters. > > Well, then you could design around a ft232 [1]. > But would RS232 suffice for 8ch/24bit/44.1kHz (12Mbit/s) ? My project was relatively slow speed. RS232 wouldn't begin to come close enough for even 1 channel :( The FTDI chip would just about manage one channel, but I don't know how you'd convince the host computer that such high baud fake serial is possible. > Shall I interpret your answer as the main hurdle is not to convert > x channels at real time, but to get it into the computer? Indeed. the conversion itself just requires a very stable clock signal and an accurate ADC for every input and DAC for every output - well that's the theory :). Getting that lot into the computer - now that's the art! I'm not aware of any open designs, even for a pretty basic sound card, which must tell its own story. > Would a network connection solve that problem? > In that case the DACs and ADCs could reside on an embedded computer > and stream the sound data to/from the pc. And one could envision > such little things near each mic and ethernet cables or possible wifi > to the control room. Power-Over-Ethernet [2] could be helpful, and why > not throw in a pre-amp and plug it directly into the mic. > > Regards, > /Karl > > [1] http://www.ftdichip.com/Products/FT232R.htm > [2] http://en.wikipedia.org/wiki/Power_over_ethernet Ethernet looks interesting, and I know there is stuff out there, but have no idea what latency and timing issues there may be. I would imagine syncing multiple 'drops' to a stable clock might be problematic. If you're just multicasting an audio stream neither of these is especially important. P.S. I could be quite wrong about most of this - it has been known to happen :) -- Will J Godfrey http://www.musically.me.uk Say you have a poem and I have a tune. Exchange them and we can both have a poem, a tune, and a song. _______________________________________________ Linux-audio-user mailing list Linux-audio-user@xxxxxxxxxxxxxxxxxxxx http://lists.linuxaudio.org/mailman/listinfo/linux-audio-user
