linuxaudio.org

Steve Harris  writes:
> On Fri, Jan 07, 2005 at 06:02:47 -0500, Lee Revell wrote:

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>> On Fri, 2005-01-07 at 22:45 +0100, Christoph Eckert wrote:

>> > The questions are:

>> >

>> > * Would JACK be stable enough? I guess yes. Furthermore, we

>> > can make a deamon which restarts jack if it dies

Restarting JACK is not a very satisfactory recovery scheme.  All

clients ports and their connections will be lost.
However, stable versions of JACK do not crash very often.
>> > * Is JACK secure enough? Certainly jack would never be started

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>> > by any distribution per default with realtime privileges. But

>> > this is not needed for the common user, so users who need it

>> > can turn it on later.

JACK does not work very well without RT privileges.
>> > * Could JACK be started during boot time and collect audio

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>> > from any user? As discussed before, this is not necessaryly

>> > needed, JACK could also be started as soon a user logs in.

>> > But I like the idea that I can have multiple X sessions and

>> > every of these users can play audio

JACK is not designed for sharing between users.  Any shared-memory

approach like JACK would be hopelessly insecure running as root while

allowing arbitrary user connections.
JACK does (recently and still only in CVS) support running multiple

concurrent servers.  Each runs as a single user and connects to a

single card.  So, multiple users could each have their own card, or

one user could use several devices.  
One-at-a-time sequential use of a single card by multiple users works

better now.  There were formerly a number of problems with it.
>> > * One problem remains, JACK cannot use different soundcards

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>> > because of the cards quartzes. So, would we have to start a

>> > seperate JACK instance for each card?

This is currently supported in JACK CVS, but not in any release

version.
>> Linspire (formerly Lindows, then L*nd*ws or something) posted to the

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>> jackit-devel list that they are in fact using JACK as the sound server

>> for their next release.  Let's see how well they pull it off...

Yes, we'll see.  Am I just hallucinating this or did someone say they

run everything as root?  In that specialized environment, some of

these problems might be more manageable.  
(System security would suck, of course.)
> The tricky bit is stopping non-RT apps (the bings and bongs apps) from

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> messing up the deadlines for the RT apps. I would be more confortable if

> they'd made a MAS server (or gstreamer, whatever) that talks JACK, then

> you only have one non-RT app (the server) that has to be carefully vetted.

Steve is right that this is the hard part.  And, something like

gstreamer is probably the best approach.  JACK is really not intended

to be a general-purpose sound server.  Much of its success comes from

Paul's clear focus on synchronous execution and low latency.
If I had time, I'd play around with gstreamer and try to get it

working really well with JACK.  Maybe someone here could do that and

send progress reports to jackit-devel.  Give us a chance to be

proactive about fixing problems.

--

  joq