[LAU] : Netjack : like a charm :)

Joern Nettingsmeier nettings at folkwang-hochschule.de
Wed Dec 10 05:05:26 EST 2008

Mysth-R wrote:
> Hi,
> I just want to report my experience. Since several weeks now, I and a
> friend of mine were searching for a software, or an utility on Linux,
> capable of synchronizing our two computers.
> We could synchronize the transport, but there were always some things
> missing for the tempo...
> So yesterday, we decided to try netjack. Here our config :
> Two laptops connected via a router/switch with ethernet.
> One laptop with a sound card the other, just nothing.
> the laptop with a sound card was acting as the Master
> the other was acting as the Slave.
> On the Slave, you open a terminal and just  run jackd with the net
> backend : $ jackd -R -d net
> So on the master you run jackd with qjackctl like you do normally. Then
> you open a terminal and run : $ jack_netsource -h
> <>   (the ip of the slave machine)
> That's all !! I couldn't imagine that it was so easy to use. And we
> played severals hour without any deconnection.
> Now I just have to sell my sound card :) !
> By the way I would like to point up some things :
> * I would like to test the --celt option. But I can't understand what
> the "N bytes per period" option are.

torben (hohn, the author of netjack) explained to me that it's the
number of bytes used for a period (i.e. the amount of compression).
say your period size is 128. uncompressed, that would be 128 * 32bit =
512 bytes.

when you say -c 40, celt will cram that signal into 40 bytes, which
corresponds to a 512/40= 12.8:1 compression ratio.

> * It seems that xruns on the master computer made some desynchronizations.
> * On seq24, on the slave computer, I had to configure the option with
> "Jack Transport" AND "Master JACK" ... a bit disapointing... We lost so
> much time finding this very logical configuration.
> * So the problem was seq24 on the slave machine was running at this own
> tempo. If the master use 120BPM and the Slave 110, they are not
> synchronized. But if you put 120 on both, it seems to be synchronized...
> Well I think there is a bug in seq24 or something. I didn't try with
> other softwares. But I have some doubt about the real tempo synchronization.

i guess there is still an issue with jack transport over netjack.
in any case, please join #jack on irc.freenode.net, torben usually hangs
out there, and most of the testing sessions happen there.



jörn nettingsmeier

home://germany/45128 essen/lortzingstr. 11/

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