On Sun, Oct 30, 2011 at 8:56 AM, Emanuel Rumpf <xbran@xxxxxx> wrote: > 2011/10/20 Charles Henry <czhenry@xxxxxxxxx>: > >> ... feedback for a project, namely building an >> audio interface, with the goal of creating freely available schematics >> and code ... >> >> The concept is to create a modular and scalable system that allows >> users to create a sound interface with an arbitrary number of >> input/output channels. > > Great project ! > Maybe try some fund-raising ? Good point. That's a consideration that needs to be up front. > Now, say thanks to those xmos people, they have a > whole reference design ready, inclusive buyable prototype: > > http://www.xmos.com/products/development-kits/usbaudio2mc > > Note: This is based on xmos technology, XC - a C like language, that > allows implicit parallel programming. > > > I heard USB-Audio-Class-2.0 is already supported by ALSA (driver architecture), > thus this device might work OOTB or with very little effort on linux. I am floored. This leaves me about speechless. It's possibly a new direction to go--the processors themselves are about as expensive as FPGA chips. > In the following, some of my ideas: > > You could take it as base, > - modularize it further > - or add some missing components, > - make IOs balanced, > - add ADAT > - add AES3, (AES/EBU) > - add AES10 (MADI) > - add AVB > - support MIDI IO > - Allow the synchronization of two or more cards, to allow more than 6 > IN channels. That's clearly just for the development board--I think their processors can handle more channels, but the $350 development board will support up to 6 channels. It would be better to develop some board designs around the chips, and see how the cost comes out. > - Make most of it optional and modular. > - Make 1 (extensible) low-cost + 1 (all-incl.) high-end design Yes, I tend to agree. There's several different processors in their product line, and it's a good development platform to look at tiered approaches with different goals. > Since most of the modules exist, work is to connect and integrate all of it, > and the design of a beautiful case and package ;) > > > I would make most of the design digital, with the exception of pre-ADC > (analog limiter, balancer) and post-DAC (amplifier, balancer) stages. > > > You would end with about these modular stages: > > - analog inputs ADC_01 ... ADC_XX > > - ADCs would deliver I2S streams, send to a mixer (fpga ? or xmos uC) > , or directly to output modules. > > - digital IO SPDIF > > - digital IO ADAT > > - digital IO AES3 > > - digital IO AVB > > - digital IO USB 2.0 > > - digital IO IEEE 1394 (maybe) > > - digital word clock (75Ω BNC) > > - analog outputs DAC_01 .. DAC_XX, would receive digital I2S streams > > - controler , routing-, configuration- and switching module > > Digital INs would be routed to the mixer stage. > Digital OUTs, could optionally be routed back to the mixer stage, > maybe with a feedback-loop detection, to prevent damage of ear and device. > > > -- > E.R. Thanks for your feedback, Emanuel. It's sort of a game-changer to me. Clearly, there's no point in starting a project that would duplicate an existing solution. I appreciate new information like this. I'll have to think this over for quite a while to see which way I'd want to go--whether there's a worthy project goal in an FPGA based design that cannot be more easily (or more cheaply) accomplished. _______________________________________________ Linux-audio-user mailing list Linux-audio-user@xxxxxxxxxxxxxxxxxxxx http://lists.linuxaudio.org/listinfo/linux-audio-user
