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Author Topic: jack and virtual keyboard  (Read 4544 times)

Birdman

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jack and virtual keyboard
« on: January 13, 2008, 08:47:59 am »
Hi there.

This is a two part question:

1. I have installed jackd and used chgroup to audio. Users are a member of the audio group. I have started jackd with "/usr/bin/jackd -d alsa". When I open Rosegarden as a user I get an error message that it cannot connect to jack. However, if I run Rosegarden as root no such message appears. How do I get around this permissions issue?

2. I currently do not have a soundcard installed (just onboard audio chip). Is there a recommended virtual keyboard that I could use with rosegarden and jack?
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The Headacher

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Re: jack and virtual keyboard
« Reply #1 on: January 13, 2008, 09:43:51 am »
Quote
1. I have installed jackd and used chgroup to audio. Users are a member of the audio group. I have started jackd with "/usr/bin/jackd -d alsa". When I open Rosegarden as a user I get an error message that it cannot connect to jack. However, if I run Rosegarden as root no such message appears. How do I get around this permissions issue?
Run jackd and rosegarden as the same user. My guess is you started jackd as root the first time.

Quote
2. I currently do not have a soundcard installed (just onboard audio chip). Is there a recommended virtual keyboard that I could use with rosegarden and jack?
I'm not sure what you mean by virtual keyboard. In rosegarden, you can edit midisequences using the "matrix editor", and use the 'keyboard' on the left side of it. Is that what you want?

chgrp'ing jackd to audio is not very useful, unless you plan to give jackd realtime priorities: http://the.headacher.googlepages.com/jackonvectorlinux
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Birdman

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Re: jack and virtual keyboard
« Reply #2 on: January 13, 2008, 02:11:59 pm »
Headteacher,

I have changed back the group to root for jackd. However, if I launch jackd and rosegarden as user the same error occurs - rosegarden does not believe that jackd is running. I can only stop the error occuring by running rosegarden as root. This is why I think it is a permissions issue. If this is the case I am not sure what needs to be changed?

Sorry, my ignorance regarding the virtual keyboard. I have not used rosegarden before, indeed I haven't used any midi sequencer for many years. The matrix editor looks like what I was looking for and will do the job fine for now until I get the rest of the kit sorted out.
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The Headacher

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Re: jack and virtual keyboard
« Reply #3 on: January 15, 2008, 09:14:01 am »
Quote
I have changed back the group to root for jackd.
Actually, group audio is fine for jackd. What I meant was that you'd probably want to give jackd realtime priority to prevent it from skipping massively.

Quote
I have changed back the group to root for jackd. However, if I launch jackd and rosegarden as user the same error occurs - rosegarden does not believe that jackd is running.
Do other programs that need jack work?
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Birdman

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Re: jack and virtual keyboard
« Reply #4 on: January 15, 2008, 01:56:38 pm »
Quote from: The Headacher on January 15, 2008, 09:14:01 am

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Do other programs that need jack work?

Good question! The fact that I was receiving an error I interpreted as there was a problem. This is all very new to me and I am trying to find my way. I guess I need a sound card to connect to my midi keyboard to see what happens?
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The Headacher

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Re: jack and virtual keyboard
« Reply #5 on: January 16, 2008, 09:31:19 am »
Quote from: Birdman on January 15, 2008, 01:56:38 pm
The fact that I was receiving an error I interpreted as there was a problem. This is all very new to me and I am trying to find my way. I guess I need a sound card to connect to my midi keyboard to see what happens?
Rosegarden should be able to connect to jackd, if it's running.  Jack is used for audio in/out. If Jack doesn't work or if Rosegarden can't connect to it, you'll only be able to use midi tracks (send and receive midi data) with it. Rosegarden will create it's own virtual midi ports, to which you can attach other programs' midi in/out (or physical ports if they are on your system).

What I'm trying to say here, is that midi and audio are 2 different things, but I understand how that can be confusing at times.
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Birdman

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Re: jack and virtual keyboard
« Reply #6 on: January 17, 2008, 04:47:49 am »
Quote from: The Headacher on January 16, 2008, 09:31:19 am
What I'm trying to say here, is that midi and audio are 2 different things, but I understand how that can be confusing at times.
Thank you for clarifying that. I agree things can be confusing at times.

I note that there is a preference setting that allows rosegarden to start jackd if it is not running. I have tried different permutations of starting jackd and then running rosegarden and also having rosegarden start jackd. As a user nothing stops the error, only executing the apps as root is error free.
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