Re: [LAD] Jack MTC/MMC slaving

Le 10 nov. 08 à 16:01, Alex Montgomery a écrit :

> Hello and thanks for the response :)
> I've inlined my responses below:
>
> JACK does not and will not support varispeed. Therefore slaving to MTC
> is going to be pretty limited. MMC also sends some speed commands that
> could not be supported by JACK.
>
> I understand, but I think limited MTC support is better than
> nothing. That being said, I don't think it's necessary to change
> JACK for this purpose, jackctlmmc's approach of being a jack
> compliant app that can drive JACK transport by listening to MMC
> signals seems like an elegant approach.
>
>
> > There's a small program called jackctlmmc that seems to do want I
> > want, but it's a bit limited (seems pretty hardcoded) and I think
> that
> > such a desirable feature should be integrated into a more widely
> used
> > program. Any thoughts?
>
> what does "hardcoded" mean?
>
> I made that comment in ignorance. I didn't see a place in the code
> where you could choose which MIDI device/port you were reading
> from, so I assumed that it just took the first registered one or
> hardcoded (specified in code instead of parameters passed into the
> program) a particular port. On closer inspection, it seems that you
> either have to patch a midi port to the application via JACK so it
> knows which one to read from, or it just reads from all alsa midi
> signals, either of which is perfectly reasonable. I'm new to the
> JACK and ALSA APIs, and I'm still waiting on a cable order to get
> my 8-track to talk to my PC, so I can't really test to see how this
> stuff works.
>
> Currently jackctlmmc supports the "play", "stop", and "rewind"
> messages from MMC, and I'm going to play with the code to see if I
> can add support for "locate" using jack_transport_locate() so that
> players can have a primitive seek-to type of function. I think that
> even this limited subset of MMC functionality is very desirable for
> linux audio engineers. I just want to be able to sit at my 8-track
> with my guitar and play/stop, rewind, and maybe seek around without
> having to keep clicking a mouse on a JACK app.
>
> I'm surprised that jackctlmmc doesn't seem to be that widely used
> (I can't find any packages for it in the major linux distros, and
> it only seems to be distributed via source code) when it provides
> such useful functionality. I'd love to see it's functionality
> integrated into a GUI app like QJackCtl (which already has JACK
> transport buttons for play, rewind, fast-forward) instead of being
> a console application, but that's a subject for another email.
>
> Thanks for your reply,
> -- Alex
>

I think this kind of tools is a good candidate to be developed as an
"in server" JACK client. With the dbus based dynamic access of
available "in server" clients installed on a machine, it will be
quite easy to load/unload this kind of tool when needed (Netjack2
uses this model of "in server" clients).

Stéphane

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Received on Tue Nov 11 00:15:08 2008