[linux-audio-user] rosegarden/timidity nigthtmare in linux 2.6

[Chris Cannam]

On Monday 15 Mar 2004 4:51 pm, jeffrey milton wrote:
> Can anyone shed any light on these mysteries?

I'm afraid I can't tell you anything much about why your MIDI events 
don't seem to be getting through to Timidity, but I can answer some 
of the questions specifically about Rosegarden:

> $ rosegarden --existingsequencer
> DCOPClient::attachInternal. Attach failed Could not open network
> socket
>
> MYSTERY #3: What is a DCOP client/server?  Why do I need it? and
> why does it only appear when I use the --existingsequencer switch?

Rosegarden consists of two processes, "rosegarden" (the GUI) and 
"rosegardensequencer" (the real-time sequencing process).  Normally 
the GUI starts and stops the sequencer process itself; the 
--existingsequencer flag tells it to use a sequencer process that's 
already running.  It's really only of interest for debug purposes.  
DCOP is a protocol (part of the KDE libraries) that Rosegarden uses 
to communicate between the two processes, so this message is telling 
you that there is no Rosegarden sequencer already running for 
Rosegarden to talk to.  So it will in fact go ahead and start one.

> MYSTERY #4: What is the significance is General MIDI Synth #10[D] ?
> I alwasy
> see teh [D] at slot 10.  What does [D] mean?

Channel 10 is used for percussion (drums, hence the D) in GM.  
Rosegarden doesn't particularly care about that but it does mark 
channel 10 separately just in case you do.

> The only thing I see that has changed is that rosegardensequencer
> has started jack...
>
> /usr/bin/jackd -T -d alsa -d hw:0 -p 2048

Am I right in guessing you have a very new version of JACK, say 0.75 
from CVS?  If so, then Rosegarden didn't start JACK -- JACK did.  
Rosegarden will happily run without JACK if you only want to do MIDI 
and score, but it always tries to attach to the JACK server first and 
only goes ahead without it if that fails.  With a recent version of 
libjack, that attempt to attach to JACK actually causes jackd to 
start up.

That's a problem that we hadn't really anticipated (with Rosegarden).  
There is no command-line flag to tell it not to use JACK, just 
because we'd assumed the JACK attach would only succeed if you were 
already running jackd, in which case you'd probably want it.

> MYSTERY #5:  What is the '-T' option in the jack line?  I do not
> see that option in any of the docs I have on jack

The options you see are the defaults hardcoded into libjack, they 
don't come from Rosegarden.  I think -T is a magic thing that tells 
jackd to exit when the last client does.

> MYSTERY: Port 64 is 'Intel 82801DB-ICH4 MIDI - Rawmidi 0'
> [type=kernel] How do I load sounds into this external midi?  When I
> run rosegarden it shows that there are banks of instruments
> available but no sound comes out when I play "aplaymidi -p 64:0
> /Blew.mid"

This is an external MIDI port -- such as a gameport on a soundcard.  
It's no use unless you have a piece of MIDI hardware plugged into it.  
Some soundcards seem to report an external port even though there's 
no port physically on the card, in which case (I think) it's totally 
useless.


Chris