Subject:ACID slaving to MTC?

Posted by: shawn_cushen

Date:6/16/2000 2:02:00 AM

I have gathered from reading previous posts that:

1) ACID will slave to MTC (posting no. 1662)

but

2) ACID cannot follow tempo changes as a slave in real time (posting
no. 1561).

Does this mean that MTC is not able to generate tempo change
information that ACID could follow?

I think I've done my homework but haven't come to a clear
conclusion. Thanks.

BTW, posting no. 1556 seems to contradict other tech advice here when
it says "No, unfortunately Acid does not make a good slave to MTC. It
must always be the master in an MTC sync situation at this time...."
How can no. 1662 say that ACID WILL slave to MTC, and no. 1556 say it
WILL NOT. Don't understand.

Subject:Re: ACID slaving to MTC?

Reply by: pwppch

Date:6/16/2000 8:34:00 AM

>>1) ACID will slave to MTC (posting no. 1662)
>>
>>but
>>
>>2) ACID cannot follow tempo changes as a slave in real time
(posting
>>no. 1561).
>>
>>Does this mean that MTC is not able to generate tempo change
>>information that ACID could follow?
>>

Correct. MTC is a clock. It does not contain any tempo or musical
information. MIDI Clock does contain tempo information, but due to
the way ACID does its magic, the tempo information would arrive late
and ACID would respond late.


>>BTW, posting no. 1556 seems to contradict other tech advice here
when
>>it says "No, unfortunately Acid does not make a good slave to MTC.
It
>>must always be the master in an MTC sync situation at this
time...."
>>How can no. 1662 say that ACID WILL slave to MTC, and no. 1556 say
it
>>WILL NOT. Don't understand.

There is a problem (bug) with how ACID intially triggers to the
incomming start position. This can cause inconsistent start times on
each sync. The manifestation of this is also inconsitent as there
are some users that have found MTC slave to be unusable while others
report no problems.

Peter

Subject:Re: ACID slaving to MTC?

Reply by: shawn_cushen

Date:6/16/2000 1:27:00 PM

>>Correct. MTC is a clock. It does not contain any tempo or musical
>>information. MIDI Clock does contain tempo information, but due to
>>the way ACID does its magic, the tempo information would arrive
late
>>and ACID would respond late.
>>
>>There is a problem (bug) with how ACID intially triggers to the
>>incomming start position. This can cause inconsistent start times
on
>>each sync. The manifestation of this is also inconsitent as there
>>are some users that have found MTC slave to be unusable while
others
>>report no problems.
>>
>>Peter
>>

Peter,

I think this will be my last question on this matter.

So if I want to have real-time tempo changes in my music (for ritard,
rallentando, etc.), will I have the ability to program them in ACID,
then slave my sequencer to ACID utilizing MTC?

Thanks,

Shawn

Subject:Re: ACID slaving to MTC?

Reply by: pwppch

Date:6/16/2000 7:44:00 PM

>>So if I want to have real-time tempo changes in my music (for
ritard,
>>rallentando, etc.), will I have the ability to program them in
ACID,
>>then slave my sequencer to ACID utilizing MTC?

Shawn:

If you have an ACID project that has tempo changes and you want your
sequencer or external drum machine to follow the tempo changes, the
you have to set ACID up to generate MIDI Clock, not MIDI Time Code
(MTC).

MIDI Time Code is a clock. It follows the time it takes to play and
communicates no tempo informtion.

Lets say in your case your main song goes from 120 bpm to 80 bpm. The
if ACID were generating MTC, and say your tempo change occured at
exactly 1 min into your song. After 80 beats of your song played at
80 bpm, the time would be 2 min. However if your tempo went from 120
to 100, after those 80 beats played, the MTC clock would be at 1 min,
48 seconds. Your song is at the same place, it just took less real
time to get there. (I am ignoring the MTC format wierdness you can
get into and just assuming that the MTC clock is the same as "clock
on the wall" time.)

MIDI Clock will adjust the number of clock pulses it outputs based on
the tempo. The timing msgs are sent out at the rate of 24 per quarter
note. For a song in 4/4 time playing at 120 bpm, you will get 24 msgs
every 1/2 second. The same song played at 80 bpm will produce 24 msgs
every 3/4 of a second. At 180 bpm, you get 24 msgs every 1/3 of a
second. The slave of the MIDI Clock sees the change in frequencey of
the clock msgs as tempo changes and adjusts accordingly. So when your
ACID project hits bar 70, beat 3 - regardless of any tempo changes -
the sequencer will be at the same place as the number of MIDI clock
msgs (24 per quarter note) will indicate exactly where in the song it
should be playing.

As far as programming tempo changes, ACID allows you to drop as many
tempo changes allong the time line as you want. How you map these
over to a ritard, rallentando, or allegro, is something your will
have to work out. For example, your tempo is 120, and you want to
retard to 80 over 2 measures (4/4 time). You could drop 5 bpm tempo
changes on every beat for 8 beats. This would be a very linear
change. To make it more natural, you may want to move in to 100 very
fast - say over 2 beats, and then move slowly over the next 6 beats.

Hope this makes this clearer...if not, let me know.

Peter

Subject:Re: ACID slaving to MTC?

Reply by: shawn_cushen

Date:6/16/2000 11:41:00 PM

Peter,

Thanks for clarifying for me regarding Digi 001 compatability and
using ACID to generate MIDI clock. I'm definitely going to get ACID
and want to configure an optimal MIDI/digital audio setup for using
with it. I'll probably be going with Logic Audio and MOTU 2408 and
MIDI Timepiece setup because they're all native to the PC.

I appreciate your help!

Shawn Cushen