[LAU] Open Sound Interface project beginnings

[Emanuel Rumpf]

2011/10/20 Charles Henry <czhenry at gmail.com>:

> ... 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 ?

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.

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.
- Make most of it optional and modular.
- Make 1 (extensible) low-cost  + 1 (all-incl.) high-end design


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.