M-AUDIO Pro Tools Recording Studio - Manual (Page 692)

Pro Tools Reference Guide 674
material equally. However, when working with
sample-based (non-Elastic) audio on tick-based
tracks, tempo changes affect the start location of
audio regions, but not their duration.
Since the length of each sample-based audio re-
gion in a track is unaffected by changes in
tempo, existing automation data is not aligned
with the audio after a tempo change is made to
a tick-based audio track.
Minimizing Automation Drift
In general, automation drift is more pro-
nounced with larger sample-based audio re-
gions. By creating many small regions, the ef-
fects of automation drift can be minimized,
because the start points of each subsequent re-
gion changes as the tempo changes. When
tempo is decreased, automation expands. When
tempo is increased, automation contracts.
Tempo Changes and Tick-Based
Elastic Audio Tracks
Regions on tick-based, Elastic Audio-enabled
tracks apply Time Compression and Expansion
(TCE) based on tempo changes. For simple
tempo changes, regions on tick-based Elastic Au-
dio-enabled tracks automatically conform to
match the new tempo. Tempo changes do not
affect sample-based, Elastic Audio-enabled
tracks. In Figure 41 below, the first two-bar re-
gion is at its native tempo of 120 bpm. The sec-
ond two-bar region has been conformed to the
tempo change of 100 bpm. Since the second re-
Tempo changes applied to (non-Elastic) audio regions
When tempo changes on a tick-based audio track...
...automation gets out of sync with audio.
Tempo at 120 bpm
No Elastic Audio
Tick-based
Tempo at 146 bpm
Tempo changes applied to small sample-based regions
on a tick-based track
To break an audio region into smaller re-
gions, use Beat Detective. For more informa-
tion, see Chapter 28, “Beat Detective.”
You can also separate regions at transients
or based on the current grid resolution. For
more information, see “Separate Com-
mands” on page 496
Using many smaller regions...
...keeps audio aligned with automation changes.