Re: [Jack-Devel] Writing an IEEE 802.1BA (AVB) compliant network backend for Jack2

On Tue, Mar 01, 2011 at 02:34:27PM -0500, Paul Davis wrote:

> > Jacktrip is used regularly for remote concerts or jam sessions with two or
> > more remote locations at the same time. Depending on the remoteness of the
> 
> not only that, but both netjack and soundjack
> (http://www.soundjack.eu/) *have* been used across WAN's (though not
> the Atlantic) for live distributed performances (with a "fast lockstep
> beat" to it).

Firstly, I don't see why adding some AVB functionality should replace
any of those tools (netjack/soundjack). To me, these are completely
different use cases with some overlapping cases.

One thing is to stream some audio at high latency of 50ms or whatsoever,
the other thing is to derive media clocks from a global network clock on
a LAN.

For this, just to answer one comment by Torben, it doesn't actually
matter whether the kernel or ptpd is asking for HW timestamping. (just
to avoid the impression I was ever implying jackd, a jack client or the
backend should do PTP itself)

Anyway, I still don't see that any of these remote jam sessions require
*synchronous* operations (as in "one clock domain"). It's multichannel
UDP streaming with fast capture and playback on both ends, some SRC and
that's it. From your comments, netjack seems to serve this use case
well, and that's fine.


I wonder what we're discussing at all? Ah, right, me asking if remote
jam sessions do exist. Obviously. Is it common? I don't think so. Might
change once we all have <30ms RTT home to home, and not just university
to university. I have <2ms to a nearby (~60km) university, and I believe
netjack could make sense in this scenario. Plenty of bandwidth, low
latency, probably not much jitter.


Cheers

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