How tempo changes affect automation

A track’s automation Time Base property (see Automation time base) determines what happens to automation envelopes when you change the project tempo. Automation can be locked to absolute time or musical time. You specify the time base in the Track Properties Inspector’s Automation section (see Properties Inspector - Track Properties and Automation section). The two Time Base options are as follows:

Musical (M:B:T). If the track is set to the Musical time base, the automation’s M:B:T position stays constant, and its absolute position shifts. Automation nodes move to match the changes in tempo.

Absolute (SMPTE). If the track is set to the Absolute time base, its absolute position stays constant, and its M:B:T position shifts. The track’s automation is unaffected by changes in tempo, and existing automation will no longer be aligned with the audio after a tempo change.

In general, it when applying tempo changes to a project that contains MIDI tracks and stretch-enabled audio clips, it is recommended to set the automation Time Base to Musical.

 

Note: If an audio clip’s Time Base is set to Absolute, the clip’s length is unaffected by changes in tempo. As a result, existing automation envelopes will no longer be aligned with the audio if the track’s automation Time Base is set to Musical.

 

See:

How tempo changes affect audio clips

Tempo track

Tempo Inspector

Changing tempos

Using the Tempo track

Using the Tempo Inspector

Using the Transport module

Using the Tempo commands

Setting the project tempo by tapping

Offsetting the tempo map

Setting the project tempo from an audio recording

Setting the project tempo from freely recorded MIDI or audio

Aligning measure/beat boundaries manually

Setting the Metronome and Tempo settings

Backwards compatibility

Tempo