[PD-dev] jack dbus?

katja katjavetter at gmail.com
Wed May 29 14:21:10 CEST 2013

On Tue, May 28, 2013 at 7:08 AM, Jonathan Wilkes <jancsika at yahoo.com> wrote:

> So, I'm curious about this:
> http://trac.jackaudio.org/wiki/JackDbusPackaging
> Specifically the "D-bus only JACK" route.  _If_ it works reliably (and of
> course that's a big if) then it gives the best of both worlds: all cases
> 1,2, and 3 above are covered by the JACK server automatically starting and
> Pulse getting out of the way for it.  Moreover, Pulse clients get routed to
> JACK with what I take are "sane" defaults.  So, if you have Pd running
> through JACK with this setup and then you open up a youtube video in
> Firefox, Pulse will automagically make a connection to JACK for it and (I'm
> guessing) hook it up to the output.
> Any thoughts on this?  I'm thinking if we could build up a body of knowledge
> on this approach it would be the easiest way to get worry-free audio setups
> with GNU/Linux distros that wouldn't give new users headaches.  Plus it
> would scale up: if they learn and care about insanely low latencies, they
> are already using JACK so it's just a matter of firing up qjackctl or
> whatever and configuring the audio server they've been using.
> Anyway I'll do some testing with it on Debian Wheezy over the next month.
> If anyone wants to try on other distros that'd be helpful (Linux Mint,
> Ubuntu, etc.)

I checked it on Xubuntu: running Pulseaudio as an audio submixer
through JACK . In Pulseaudio's mixer GUI (which is the default mixer
in Xubuntu's panel), JACK can be selected as destination for an
application's audio output, but only when the application is indeed
delivering audio. For example, when a video is playing in Firefox, the
audio interface option boxes appear.

Setting up the connections manually is time-consuming. But, since JACK
adds some latency to Pd, I would not use it as default (autostart)
setup. The lowest practical roundtrip latency through Pd I could get
in the JACK-with-Pulseaudio setup was measured 50 ms, 32 ms more than
directly through ALSA.

Is there not another way to play sound files or tutorial video's
together with Pd? I found one nice alternative: make VLC JACK-aware
and use it to play media files and network streams through JACK. To
prepare the setup:

- install vlc package (multimedia player and streamer) if it's not
already installed
- install vlc-plugin-jack package
- in VLC preferences, set audio output to JACK

A Youtube video can be played in VLC via menu Media >> Open Network
Stream. It should be possible for other streams as well but I still
have to find out how to do Vimeo or Soundcloud. The VLC/JACK route
would not be most convenient to watch internet video clips on a
regular basis. However for incidental use, the advantage is that VLC
connection is quickly made in JACK.


> Best,
> Jonathan
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