Re: [LAD] embedded high end audio

On ds, 2008-08-02 at 13:07 +0200, Fons Adriaensen wrote:
> On Sat, Aug 02, 2008 at 01:01:12PM +0200, Pieter Palmers wrote:
> > Florian Faber wrote:
> > > Peter,
> > >
> > >> I doubt that it is easy over a transport protocol that doesn't have a
> > >> global absolute time reference (like ethernet).
> > >
> > > What time reference do you have in mind on ethernet that can be used as
> > > word clock source?
> >
> > My formulation is a bit unfortunate. I mean that ethernet does NOT have
> > a global absolute time reference. And word clock is not a time
> > reference. It's a 'rate' reference, which does not contain absolute time
> > information. What you need to output signals on different devices with
> > sample accurate phase is an absolute time reference. Which ethernet does
> > not have.
>
> The solution I'm using in this case is to distribute
> a single audio signal (similar to the one used in jdelay)
> to all computers. The signal can be decoded into a sub-
> sample accurate time, and all network data are timestamped
> using this time scale.

Very interesting project indeed.
Up to how many channels the (gigabit) ethernet would be able to scale?
Could the synch audio signal be "linked" from one station to the next,
or should they all receive from a central server? The first would enable
many stations without needing a huge central multichannel device.

Pau

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Received on Sun Aug 3 04:15:01 2008