Re: Event sensing

>  Is it possible yet in perl [to do real-time event monitoring]?  

Note that since the granularity of MIDI isn't much smaller than half a
millisecond, and even the low-end machines these days go through LOTS
of cycles in that time, you don't truly need real-time response (or at
least, "real-time" in MIDI terms isn't as stringent a requirement as
it used to be)

If your midi device driver is such that you get a filehandle you can
call select() on, then you're in business.

In this case, writing Perl code to deal with midi events coming in is
essentially no different from, say, writing a mail server in Perl,
which has already been done a few thousand times.  
 

If select() *doesn't* work on your midi device, then you're either
polling (i.e., watch everything else on your machine slow to a
crawl...) or you're off in Multithreaded Programming Hell, e.g.,
having a separate midi reader thread that stays blocked waiting for
events, while your other thread(s) manage your sequencing and whatever
else you're doing...

which is perhaps not as horrible as I'm making it out to be --- some
would argue that it's actually EASIER to have different tasks off 
in different threads and not having to write one big select() loop 
with EVERYTHING funneling through it.  However, since Perl's multithread
support is still slightly wonky (or so I infer from the EXPERIMENTAL
warnings I saw in the docs last I looked, and the fact that the
ActivePerl binary distribution still leaves it all turned off...), 
this may mean 

(*)  having to do n-1 of your threads off to the side in C code, and thus
(*)  having to learn how to write a C extension,... 

which then probably doesn't qualify as "in Perl".


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   From: "Scott Webster Wood" <[email protected]>
   Date: Wed, 19 Dec 2001 17:01:31 -0500
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   I played a few months back with some of the perl midi tools but wasn't
   highly impressed with the real-time event monitoring on receive.  I have an
   AX-1 and  MOTU that I use to connect to my laptop.  I will likely also get
   the expansion base so there is less of a fuss trying to find linux drivers
   for the MOTU and/or my sound canvas pc-midi interface.  Anyway - I have
   wanted for some time to be able to monitor a midi channel for key strokes to
   trigger 'sounds' on my PC.  I will have no problem programming the sound
   library or the playback, but I am wondering if anyone has opinions on
   real-time event monitoring.  Is it possible yet in perl for an application
   like this?  (i.e. - hit a particular key, and play back a particular audio
   sample - these are sound effect mind you, like south park quotes, monty
   python, etc)

   Scott



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