On Wed, Dec 28, 2011 at 1:46 PM, Iain Duncan <iainduncanlists@gmail.com> wrote:
> Hey folks, what is the easiest way to deal with midi input in a jack app?

Dave mentioned that you want to use the Jack API entirely, I think he probably meant
that on Linux you can safely rely in having an access method that just takes MIDI
from Jack - then converts to whatever messaging you want within your app. I may
be wrong. The issue is that you put in that extremely awkward caveat which was "easy
to port to other systems". I would not really want to have my whole source code having
a line like #include <jack/midiport.h> to work. Even if that line is in a private, global
header file it implies the code is dependent and that reduces portability.

If you want maximum portability you probably need to create your own internal
event messaging format and have raw MIDI, ALSA MIDI, Jack MIDI (or OSC, or
Portmidi, etc) map into it using libraries.

It is a bit more work but fortunately there is a reasonable amount of commonality
in the external formats so your library will mostly be concerned with what is the
access method to those data formats rather than the format itself.

Not sure if that answers your question. You asked what was the easiest way. The
easiest way is get somebody else do to it but I think your own your own here? The
main thing you want to avoid is that when you pass these 'musical event' messages
around your application that you are relying on a format from somebody else' library
since if you try and port that over to another system you will have a dependency on
what might be a non-native interface on that other system.

If you are going to support lots of different interfaces then you get into some really
enjoyable special cases. For example, when MIDI is not delivered into the RT audio
thread you need a ringbuffer to send at least some of the messages to that thread.
Conversely when you use Jack you have to decide which messages are not really for
the RT thread and throw them the other way on another such ringbuffer. When you
talk about having multiple MIDI interfaces you will be directly affect by these issues
at the same time.

> what is the easiest way to deal with midi input in a jack app?

Hm, there might not actually be an answer to this question since you put in that
damn caveat - you don't actually seem to want a Jack application.

Have fun. Or, if you can, get somebody else to have that 'fun' for you.

Kind regards, nick.

"we have to make sure the old choice [Windows] doesn't disappear”.
Jim Wong, president of IT products, Acer