Re: [LAD] embedded high end audio

On ds, 2008-08-02 at 23:32 +0200, Pau Arumí wrote:
> 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.

Yup, ignore the last question -- the synch signal is the same for all
stations so one output split to many inputs is enough. Easy. :-)

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Received on Sun Aug 3 04:15:02 2008