User Manual

Pro Tools Reference Guide16
Tick-Based and
Sample-Based Time
Pro Tools lets you set any track timebase to
either sample-based or tick-based. You can also set
the Timeline to be viewed as tick-based or sample-
based.
Audio in Pro Tools is sample-based by default.
This means that if an audio clip is located at a par-
ticular sample location, it will not move from that
location if the tempo changes in the session—
though its Bar|Beat location will change.
MIDI data in Pro Tools is tick-based by default.
This means that if a MIDI clip is located at a par-
ticular Bar|Beat location, it will not move from that
Bar|Beat location if the tempo changes in the ses-
sion—though its sample location will change.
You can select whether a track is sample-based or
tick-based when it is created, or change timebases
later.
Sample-Based Audio and MIDI
With a sample-based audio track, all clips in the
track have an absolute location on the Timeline.
Clips stay fixed to the sample time, regardless of
where tempo or meter changes occur in a session.
If you make a MIDI track sample-based, all MIDI
events in the track have an absolute location on the
Timeline. MIDI events stay fixed to sample time,
regardless of any tempo or meter changes in a
session.
Tick-Based Audio and MIDI
Tick-based audio is fixed to a Bars|Beat location,
and moves relative to the sample Timeline when
tempo and meter changes occur. However, MIDI
events and tick-based audio respond differently to
tempo changes with respect to duration. MIDI note
events change length when tempo or meter is ad-
justed, while audio clips do not (unless Elastic Au-
dio is enabled). When Elastic Audio is not enabled
on an audio track, meter and tempo changes affect
only the start point (or sync point) for each audio
clip in a tick-based track. If Elastic Audio is en-
abled on an audio track, tempo changes apply Elas-
tic Audio processing, which changes the duration
of the audio clip.
Elastic Audio
Elastic Audio provides real-time and non-real-time
(rendered) Time Compression and Expansion
(TCE) of audio. Tick-based Elastic Audio tracks
actually change the location of samples according
to changes in tempo. The audio stretches or com-
presses to match changes in tempo. Elastic Audio
also provides high-quality non-real-time clip-
based pitch shifting.
Pro Tools Elastic Audio uses exceptionally high-
quality transient detection algorithms, beat and
tempo analysis, and real-time or rendered TCE
processing algorithms. Elastic Audio lets you
quickly and easily tempo conform and beat match
audio to the session’s Tempo ruler. It also provides
an unprecedented degree of control over transient
detection and TCE processing on an event-by-
event basis.