Re: [Jack-Devel] C++ development of Jack enabled applications--particularly SysExec

PrevNext  Index
DateWed, 04 May 2011 23:47:20 +0100
From Harry Van Haaren <[hidden] at gmail dot com>
ToSean Beeson <[hidden] at gmail dot com>
Cc[hidden] at jackaudio dot org
In-Reply-ToSean Beeson [Jack-Devel] C++ development of Jack enabled applications--particularly SysExec
Follow-UpSean Beeson Re: [Jack-Devel] C++ development of Jack enabled applications--particularly SysExec
Hey!



On Wed, May 4, 2011 at 10:39 PM, Sean Beeson <[hidden]> wrote:

> Since in QjackCtl under the Connections everything, other than audio
> signals, are under the ALSA tab anymore, has everyone dropped using Jack
> midi ports and Jack is making midi connections with ALSA. What is that or
> the difference of those? :-)
>

ALSA midi still exists, its used by some apps, but JACK midi is preferred
for JACK-Capable apps, as the MIDI stays sample accurate with the Audio
stream. When using ALSA for MIDI & Jack for audio this is not the case. Most
newely released MIDI programs will support JACK midi.


> Secondly, I want to do this in C++ because I already have OOP in my brain
> and I have run into some wiki discussions about needing to use a wrapper for
> the best results. Considering my first question, what's the common trend on
> that?
>

I just use the standard  jack.h  c header, and wrote my own class around
that... there is a "jackmm" file up on sourceforge, I belive it works but
have no experience. Most of the docs online refer to the C API, so I'd stick
with that one to have a reference to look at.. Your choice though!


> Lastly, since Jack has some issues with sysexec information, has anyone had
> good luck with Jack and sysexec messages? I do send small sysexec messages,
> say for one or two parameter changes, without a problem in Rosegarden, but
> large amounts of data doesn't work so well.
>

Currently JACK doesn't support large sys-ex messages. (Correct me if im
wrong JACK-devs..) but I think the reason is to do with the size of the MIDI
buffer that JACK uses. It wouldn't make sense to make it an arbitrary
"large" size, as one could technically over-flow the buffer. So at the
moment (again I'm not the most experienced) but I belive that JACK MIDI uses
a buffer that holds the standard "3 part" midi message, (ie: a bufffer that
contains 3 char's.)

Finally, you've set quite a high goal for yourself with the editors, I
personally wouldn't be up for a project so large as my first.. But if you
have program design experience & whatnot, don't let me discourage you!
Cheers, -Harry
PrevNext  Index

1304549259.20890_0.ltw:2,a <BANLkTi=AGbbwaKjkoPk6eXbyvVX6YBai_w at mail dot gmail dot com>