[LAD] FOSS Ethernet Soundcard

[Folderol]

On Tue,  1 Dec 2009 19:31:24 +0100 (CET)
karl at aspodata.se (Karl Hammar) wrote:

> Patrick Shirkey:
> > Just to recap. These are the points that have been discussed so far.
> > -------------------
> > Physical Size
> > -------------------
> > 
> > http://www.rittal.com/products/ArtikelDatenblatt.asp?ArtNr=1360500&lang=GB
> > 
> > 600 mm x 600 mm x 350 mm
> 
> No, this is where I will put my system into. The actual "computer" 
> would be much smaller. I'm planning on something like
> 
>  h: ~240, w: <200, d: < 200mm
> 
> But I don't think you should have to abide to that.
> 
> +++++

At this stage, I'd just say whatever is easiest to work with. Shrinkage
and prettifying can come later!

> For the "soundcard" part, it might be more useful if we instead talk 
> about interfaces.
> 
> With SPI, we are free to "attach" many different cpu-cards, it's just 
> clock, data out, data in, and a few chip select lines. And we can 
> potentially get 10-20 channels at cd quality.
> 
> With faster i/o, we can use the cpu's memory interface, or
> some ordinary bus like pci or pci-x.
> 
> I'm not for pci or pci-x at this point, since that would be for me a 
> totally different project. Unless, of cause, someone else takes care 
> about the "bus" part, and I and others do the ad/da and analog part.
> 
> With spi or the memory bus, we cannot use an ordinary pc --- to bad.
> But we could use the atmel network card mentioned a few lines below,
> or the card I will eventually build, or some card someone else provides
> source to.

PCI is on the way out and PCI-x seems to be rather fluid spi seems more
future-proof (in as much as anything can be)

> > ---------------
> > Hardware
> > ---------------
> > No decision has been made on the viability of designing a board from 
> > scratch.
> 
> I will probably do everything from scratch, but given good and
> sensible interfaces card<->card, one could possible use "any"
> suitable cpucard.
> 
> > - You have access to this board for development/testing:
> > http://www.atmel.com/dyn/products/tools_card.asp?tool_id=4102
> 
> Ack.
> 
> > The aim is to provide upto 8 audio i/o ports.
> 
> I don't think we should set an upper limit, instead it would be 
> interesting to see how many channels the system could support.

Very much agree, start simple and see how far we can push it.

> I would say we try to make (input and output)
> 
>  one desent channel, e.g. 16bits, 44.1/48kHz
>  one very good channel (if we manage), 24bits 192kHz, to try the limits
> 
> And then see how many we can fit into the system.
> 
> And, would that be an line input, or mic input channel, or
> (software) switchable?

Initially line only, much easier to get a decent performance. Also
there are *lots* of mic preamps out there and everyone thinks theirs is
the best :)

> Talking about, i/o. Would buttons, leds, relays, linear and rotary
> things (what is their name?), etc. be useful ?

KISS
Status LEDs would be good, but levels should be software controlled, so
no need for mechanical switches, Pots, Faders etc.

> > Connectivity via Gigabit ethernet.
> 
> I don't think the atmel can do gigabit. Fast ethernet (100Mpbs),
> is a more realistic choise unless we switch cpu.

Almost everyone has fast Ethernet, so lets stick with that for as long
as possible. It's easier to upgrade than downgrade!

> > --------------------------
> > Firmware/Software
> > --------------------------
> > The device will run Linux OS.
> > Audio data transfer will be via netjack using CELT compression.
> 
> Ack.

I'll just go with the flow here :)

> > -------------
> > Website
> > -------------
> > Need to define project vision, setup wiki, git-hub etc...
> 
> Ack.
> 
> I have some readme's at [2], and I will put all my other design files 
> there.
> 
> Here are some thoughts (extract from [3]):
> 
>  The requirements are
>  . it should run linux
>  . developed with open source tools, current choise is gEDA
>  . expandable, you be able to easily add e.g. 8 D/A ports, 32 DIO etc.
>    preferably hotpluggable
>  . electrically rugged and EMC safe
>  . easy to make and build yoursalf, preferable double layer card
>  . the components should be available/purchable for a normal hardware hacker
>  . the should not cost to "much"
>  . no card edge connector
> 
>  It seems that my "archetectural" choises are
>  . a single board computer
>  . a stackable system like pc104, pico-itxe or arduino
>  . a card frame system, either
>   - whith a backplane bus, like VME or CompactPCI
>   - or with the "backplane" on the cpu card, the motherboard style like ATX
> 
>  The one which is easiest to expand is the card frame system with a backpland,
>  I will make my first try with that.

Pretty much ticks all the boxes for me.

-- 
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.