[LAD] FOSS Ethernet Soundcard

Adrian Knoth adi at drcomp.erfurt.thur.de
Tue Nov 24 16:19:50 UTC 2009

On Tue, Nov 24, 2009 at 04:46:02PM +0100, Karl Hammar wrote:

> Well, you have to start somewhere. I'm not in this to compete with 
> Behringer ADA8000, I'm in this to fiddle around with soldering.

WTF? Soldering is what it takes to make the product. If soldering is the
motivation for the project, I couldn't care less. ;)

OTOH, as Gene has pointed out, a completely open source protocol
replacing ADAT is a valid motivation, so the HQ guys could still jump
the band waggon once the protocol has settled.

(given that it will ever make its way)

> One question tough. If you have ADAT, why go the longer way over an 
> ADAT-to-ethernet box than straight into your adat card in your computer?
> What would one gain?

I could then place multiple ADAT converters on the net, combine their
capacity without using MADI (64 channels over one cable), copy the
signal at the FOH (front-of-house, mixing desk), feed every musician
with his personal monitoring stream and record it.

Today, RockNet does this, all audio distribution networks do this, but
they are expensive. My impression was you want to provide this kind of
functionality for less money.

If I could save the MADI card and just plug the network cable into my
el-cheapo network card, I would have a gain.

> uint48_t ethernet_addr;
> uint32_t ip_addr = 192 << 24 | 168 << 16 | ethernet_addr & 0xffff;

I'd probably slap you when come up with code like this. ;) This is
lacking abstraction.

For those who haven't heard, yet: An IP address isn't an uint32_t. This
is the road to hell, leads to unportable code.

But since I'm working for the networking chair at Jena University, let
me tell you that the right structure for an IP address is

   struct sockaddr_storage

Nothing else. Don't even dare to shift bits in an uint32_t. Things like
this might have been right in the 90ties, but we had RFC 3493 in
February 2003 (and RFC 2553 in 1999). ;) (things might be different when
we're talking kernel level)

As mentioned in the original posting: if I could provide some input, I'd
happily do this. It's probably a good idea to decide on the goals,
first, but I might have missed that part of the discussion.


mail: adi at thur.de  	http://adi.thur.de	PGP/GPG: key via keyserver

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