Mixing : Automation : Previewing Automation

Previewing Automation
For more information, see the following topics:
(Pro Tools HD and Pro Tools with Complete Production Toolkit Only)
Automation Preview mode lets you audition changes to a mix and compare them to existing automation values without committing them to the automation playlist.
When you put Pro Tools in Automation Preview mode, you can preview values for automation-enabled controls on any track that is in a writable automation mode.
While in Automation Preview mode, when you touch or move a control, it isolates the control, disengaging it from its automation playlist. The control stops reading or writing automation, allowing you to freely audition changes.
When you have found a level or state that you want to use, you can then commit or punch the previewed value to the automation playlist for the isolated controls.
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If you punch during playback, the automation mode is set to Latch and writing begins at the preview value.
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If you punch while the transport is stopped, the automation mode is set to Latch and the control is primed at the preview value.
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It is not necessary for the Allow Latch Prime in Stop preference to be enabled for Preview to put a control into Latch Prime.