Vivotek ND8312 User Manual page 59

If you find yourself in the wrong segment on the timeline, use the buttons on the upper-right
of the screen to travel.
The definitions of these buttons depend on the time span of your current position. For
example, if you are in a 4-hour time span, the "Back to previous state button" will bring you
back to the 24-hour time span.
Previous
Back to
# hours/mins
previous state
The smallest time span is 2 minutes. And on the screen of 2-mins span, each snapshot
represents a 15 seconds video footage.
You can then click on the Play button
VIVOTEK - Built with Reliability
Next
# hours/mins
to playback the recorded footage.
User's Manual - 59