[LAU] online calls with decent auido for music lessons

David Kastrup dak at gnu.org
Fri Mar 19 15:22:04 CET 2021

Lorenzo Sutton <lorenzofsutton at gmail.com> writes:

> - Jamulus [4]: audio-only, realtime online jamming-oriented with
>   public 'servers', jack-native. This was actually real fun to test
>   and play with. I tried some close-by servers and jammed a bit in the
>   central one. With 128 frames set in JACK and using Jamulus' own
>   direct monitoring latency was definitely acceptable and the audio
>   quality pretty good. Audio-quality and music-friendliness wise this
>   is probably the nicest to use. Only thing for a teaching setting is
>   the public-only servers (the documentation mentions 'private' ones,
>   but I haven't looked into if this is possible without actually
>   'hosting' a server),

I could rent one out to you, assuming my cloud provider has some
facility in reasonable vicinity to you.

As a first measure however, you could easily run one yourself on your
own computer (running Jamulus with the -s option runs one on your
computer).  This requires punching a port through the firewall in your
Internet router and either phoning your external IP address to the
student (depending on your Internet provider, it may be fairly constant)
or setting the router up to communicate with a DynDNS account giving you
a constant name.

If your computer has enough performance and you connect your own Jamulus
client to "localhost" rather than going through the network, for a
one-on-one session it may work.  However, it means that the student
audio goes in and out the student's Internet connection and in and out
your own Internet connection.  Using a cloud server has the advantage of
halving the number of home-level routers that the student roundtrip (not
your own one) has to pass through.  And the student is less likely to
routinely deal with that latency than you would be after a while.

Of course, this consideration is moot if there is no cloud computing
facility in closer "networking" vicinity than the trip through your
private connection would take.  It may also depend on whether you and
your student share the same provider, making it more likely that routing
is able to bypass the central "Internet Highways" that tend to be "near"
the cloud servers.

> there is a workaround via soloing or muting others, but I don't think
> most teachers (nor students) would feel comfortable with anyone
> possibly coming in and listening to the lesson. Also video should be
> provided via some other tool and, of course, all parties need to have
> the software installed.

You get used to doing without.

> That said this software is really well made and fun to use.  (aside
> note there were a couple of 'troll' events in one of the public
> servers, and although they say don't feed the trolls 'audio trolling'
> can hurt your ears...

That sounds more like the typical "instructions are just
recommendations" newbie not taking serious the need to use headphones
when working without echo compensation and auto-ducking.

You know, like the only person in the conference call not affected by
echoes after they figured out they could just switch off echo
compensation without having their connection deteriorate.

> Software:
> - Jack
> - Zoom H5 shows 4 inputs in jack: the L/R mics and the inputs 1 and 2

Oh, can you just put the headphones right next to the mics (makes
astonishingly little difference in comparison to direct connections) and
use jack_iodelay for measuring out the latency of the H5 with your

Numbers are surprisingly hard to come by for any audio interface.

David Kastrup

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