RE: midi time code to clock convertor?

["Dave Hastings" <dhastings@earthlink.net>]

> Subject: midi time code to clock convertor?

> Hello all - long -long time no post- I use a
> jamman and want to use ACID software as slave,
> in order  to do this i have to get midi clock
> data out, (which ACID doesn't do ) is it possible
> to convert midi time code ( which acid DOES do )
> into clock, so i can feed this to jamman? any other
> workarounds ?

Am I correct in understanding that you want to take MIDI clock from the
jamman and slave ACID to that?

What are you trying to do?  I can see two obvious possibilities (I'm sure
there are some other non-obvious ones).

First, preventing drift between the jamman and ACID (implies you know tempo
ahead of time, and can set it in ACID).  For this, I'd suspect that it's a
lot easier generate MIDI clock in ACID and slave the jamman.

Second, setting tempo and syncing.  This unfortunately can't be done (not
entirely true, see below).  MTC is entirely tempo-less.  It's based on a
specific number of frames/second, and the number of frames is part of the
format.  (For instance if you set ACID to look for 30fps and send it 24fps
MTC, it doesn't sync).

All of that said, within limits you can play around with the rate at which
the MTC quarter frame messages are delivered, and still sync.  I whacked
together some code for keykit to generate MTC, and synced (sunk?) ACID to
that.  I found that it would sync with actual frame rates from about 1/2 to
2 times the rate specified.  Unfortunately, as you might expect, the pitch
of the played back material depends on the actual rate of the quarter frame
messages.  It's also worth noting that ACID doesn't sync instantly to MTC,
so it takes some small but noticeable amount of time to start playing after
you start generating MTC (this is true even with properly timed MTC
messages).

So if you're inclined to do some experimentation and coding you could get a
copy of keykit, which can receive MIDI clock, and use it to generate MTC.
I've got some code to generate MTC that you're welcome to (hacked together
test code).

You can get keykit from http://nosuch.com/keykit/.  It's available as
binaries for Windows, Linux, and Mac (v6 only), and as source.  Version 6
only supports a single input port and a single output port.  Version 7
supports multiple of both.

-daveh
--------------
Dave Hastings
dhastings@earthlink.net
"An intellectual snob is someone who can listen to the William
 Tell Overture and not think of the Lone Ranger."

 - Dan Rather