[Update] jackd won't start

[leftbas]

Help! I'm having the damnedest time getting my Gentoo box ready for multitrack audio recording. Jack just won't cooperate. I'm running kernel 2.6.10 r6, and this is the furthest I've been able to get:

[FishB8]

First, jack won't start when amarok is running because amarok is already the device node it needs access to. You con only connect multiple programs to an AlSA device node at the same time by setting up ALSA with dmix, but you don't want that if you're going to be doing multitracking. (dmix slows jack down)

Second, try to use different buffer sizes and number of periods. Each sound card has different size buffers, and some can be set to only use part of the buffer while others must set to an exact buffer size. Mess with buffersizes, periods, and even sampling rates.

You can probably google and find info about running jack on your particluar hardware.
_________________
"...as we enjoy great advantages from the inventions of others, we should be glad of an opportunity to serve others by any invention of ours, and this we should do freely and generously." -Benjamin Franklin

[leftbas]

Thanks for the tips. Unfortunately, none of them worked. But I did end up getting Jack to work. And I managed to get it to run while amaroK is running.

First I emerged jackctl, the QT-based interface for Jack. I figured that since I was having such trouble with the CLI, I thought it might make it easier by showing me all the options at once. And it did. I saw someone post a comment about the realtime switch in jackd, so I started playing around with that. First I changed the priority a bit, but I had no idea what to change it to. And since none of the settings I chose worked, I disabled it. And the damned thing started!!! I was so stoked!!!

Now I have trouble with Rosegarden. It keeps bitching about the audio sequencer not being able to start. But Ardour starts just fine. I just don't like the interface, so I unmerged it. (Maybe I'll fool around with it later, if I end up not liking Rosegarden.) So I unmerged Rosegarden 1.0 and I'm in the middle of emerging 0.9.8, which is the latest unmasked package. We'll see what happens.

But now my question is this: what effect will disabling realtime have on recording and playback. And if I must leave it enabled, what number should I set it at? The screenshot on http://qjackctl.sourceforge.net/qjackctl-ss1.html shows a setting of 60; I'm not sure, but I think mine was set to 2 by default. I can't say for sure, cuz I'm at work instead of at my machine right now.

Any ideas
_________________
"In retrospect, everything is funny."
-- anonymous

[leftbas]

BTW, does anybody have any idea while jack is so poorly documented? Do the devs intend for us to rely on a man page and each other to figure out all the idiosyncrasies of that thing?

Just curious.
_________________
"In retrospect, everything is funny."
-- anonymous

[FishB8]

Generally you don't need to worry about realtime unless you need to do mulitrack recording with jack set at a low latency. If you need realtime you will need to add the realtime-lsm module before you can use it as a non-root user.

Not using Ardour because you don't like the interface is a poor reason not to use it. It's capabilities are quite impressive.

Rosegarden is ok, but it's generally used more for midi sequencing. If you prefer it though, it does have audio mixing capabilities. The sequencer problem might be that you don't have the alsa sequencer module loaded.

Jack documentation is pretty straight forward. It's a pretty simple concept from the user standpoint. You might try browsing through the FAQ for some general info: http://jackit.sf.net/
_________________
"...as we enjoy great advantages from the inventions of others, we should be glad of an opportunity to serve others by any invention of ours, and this we should do freely and generously." -Benjamin Franklin