An edit, every position a duration from the original recording's start.
Optional
Keep only this stretch. Either end may be left out.
The recorded lap starting at each of these (within a second) joins the lap before it.
A new lap starts at each of these.
Split the recording into several activities: a new one starts at each of these (a run, then the walk home).
An edit, every position a duration from the original recording's start.