User Manual

Pro Tools Reference Guide688
Controller and Program Chasing
Pro Tools always chases continuous controller
events and program changes for MIDI tracks.
This ensures that controller values and patches
for MIDI devices are always set correctly.
For example, suppose a MIDI track lasting 32
measures starts with a MIDI volume of 127 and
in the last bar fades down to 0. If after playing
the track in its entirety you attempt to play from
bar 8, the initial MIDI volume of 127 is chased
and sent to the track’s assigned device—other-
wise the track would not be heard since the most
recent volume event sent would have been 0.
Chasing also occurs for a MIDI track’s default
program change, along with any program
change events residing within the track. There-
fore, if you have chosen a default program
change for a track, when playing from any point
within the track, the program change event is
sent to the track’s assigned device.
Default Controller Values and
Chasing
Though new MIDI tracks appear to have default
values for continuous controller playlists, this is
actually not the case. For example, when view-
ing a MIDI track’s Mod Wheel playlist, you’ll see
that the breakpoint line is set to a default of
zero. However, since the modulation wheel on
your MIDI controller may be purposely set to a
different value, the default value in the track is
not transmitted when playing.
For example, if you record Mod Wheel automa-
tion that changes from 0–90 towards the end of
the track, and you then play from the beginning
of the track, or from anywhere before the
change, having the Mod Wheel value remains at
90 until the 0 value is reached is not likely to be
what you want.
To ensure that the default controller value for a
playlist is sent (and chased), click the initial
breakpoint at the beginning of the track, move
it slightly, and set it back to the default value.
Offsetting MIDI Tracks
Pro Tools can offset MIDI tracks globally or indi-
vidually.
Global MIDI Playback Offset
Pro Tools provides a preference for MIDI offset
that lets MIDI and Instrument tracks play back
earlier or later (than audio tracks) by the speci-
fied number of samples. The offset affects play-
back only and does not alter in any way how
MIDI data is displayed in the Edit window.
This capability is provided in large part to com-
pensate for the audio monitoring latency in
host-based Pro Tools. If you are monitoring the
output of external MIDI instruments with an ex-
ternal mixer or sound system (or headphones),
there is no latency. If, however, you are moni-
toring the output of your MIDI devices through
a Pro Tools interface (such as 003 family de-
vices), your MIDI tracks sound slightly later
than your audio tracks. The larger the setting for
the H/W Buffer Size (128, 256, 512, or 1024 sam-
ples), the larger the latency.
When Delay Compensation is active, MIDI
and Instrument tracks are automatically de-
lay-compensated to provide low latency
monitoring. For more information, see “De-
lay Compensation for MIDI” on page 961.