[LAU] Ubuntustudio 12.04 audio?

Len Ovens len at ovenwerks.net
Sun Aug 19 17:33:28 UTC 2012

On Sun, August 19, 2012 6:37 am, Mac wrote:
> Hi,
> Does anyone know of an overview of how audio in Ubuntu Studio12.04 works?
> I've made some mods to other debian builds. Before I spin my wheels a lot
> jaunted to see the lay of the land.
> One particular question is how the names of sinks/sources get conjured in
> jack when I plug in a firewire device. And how the patching gets defined;
> on this PC the firewire Ports get assigned to all the I/O on the PC.
> Frontleft, frontright, rearleft, etc.

In jack the channels are listed as system/capture_1 to system/capture_n
and system/playback_1 to n. If you are only using jack, and not pulse,
those are the only ones you need to worry about.

However, because you are using a FW device I think you are talking about
the pulse/jack bridge for use with desktop sounds like firefox flash
stuff. For a pulse device, you can choose from stereo, 4.0,4.1,5.0 or 5.1.
What should happen is that the jack bridge should be treated as a device
and have it's own configuration... in the case of alsa and jackdbus it
would be nice if it just used whatever is set up for the same alsa device.
These things don't happen and so if what you want pulse to jack in just
stereo, pulse has to be manually configured for that. (means editing
pulse's files) I suppose from Pulses view, defaulting to surround makes
sense, but for any serious audio work stereo seems best. The surround
stuff is massaged so that left and right in do not equal left and right
that jack sees.

The reason that the pulse audio connections are in an odd order is because
qjackctl lists the ports in alphabetical order.

This stuff is something that needs fixing, or more likely working around
as pulse is desktop centric and in general feels that there is no place
for other audio backends. As such you will find that many people in this
list just remove pulse :)  If you are only doing audio manipulation and
are not doing desktop audio apps (audacity works better with pulse BTW,
but for browsing and stuff like that pulse is needed) then that may be the
best answer.

Len Ovens

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