DigiDesign Digidesign Pro Tools 8.0, Reference Manual

Page: 361 / 1112

Chapter 17: Playing Back Track Material 343
3
Select the devices you want to receive MIDI
Beat Clock. If your MIDI interface does not sup-
port transmitting MIDI Beat Clock to separate
ports, only the interface appears as a destina-
tion.
4
Enter the correct negative offset values (such
as “–200” samples) for each port that is enabled
for transmitting MIDI Beat Clock (see “Measur-
ing Beat Clock Latency” on page 343).
5
Click OK .
Sending MIDI Beat Clock Over IAC
(Mac Only)
You can synchronize other MIDI applications
that use the Apple Inter-Application Communi-
cation (IAC) driver to Pro Tools by transmitting
MIDI Beat Clock on the IAC bus.
To transmit MIDI Beat Clock on the IAC bus:
1
Choose Setup > MIDI > MIDI Studio .
2
In the MIDI Devices window of Audio MIDI
Setup, double-click the IAC Driver icon.
3
Configure the IAC Driver ports and confirm
that it is online.
4
Choose Setup > MIDI > MIDI Beat Clock .
5
In the MIDI Beat Clock dialog, select the
En-
able MIDI Beat Clock
option.
6
Select the IAC Driver ports you want to enable
for sending MIDI Beat Clock.
7
Click
OK
.
MIDI Beat Clock Offsets
You can set an offset for MIDI Beat Clock on a
port-by-port basis with your MIDI interface and
external MIDI devices. This lets you adjust the
timing for each device where some devices
sound late due to different, fixed latencies.
Where appropriate, enter negative offset values
in samples for each port to correctly synchro-
nize the audio signals from your external MIDI
devices with Pro Tools playback.
Measuring Beat Clock Latency
To determine the correct MIDI Beat Clock offset
for an external MIDI device:
1
Ensure that your computer and external MIDI
device are correctly connected and configured
for MIDI, and that its audio output is correctly
connected to audio inputs on your Pro Tools au-
dio interface.
2
Ensure that your external MIDI device is con-
figured to receive MIDI Beat Clock, and that it is
correctly configured to play back a simple rhyth-
mic pattern “on the beat.”
3
Create a new Pro Tools session.
4
In the MIDI Beat Clock dialog, ensure that
MIDI Beat Clock is enabled and that the device is
selected.
MIDI Beat Clock dialog