Markers

Markers are time-stamped pins you place on a video frame to capture a specific moment in a race or training swim. SwimLab uses markers to calculate splits, measure underwater distance, and identify technical events.

Marker Types

SwimLab has seven built-in marker types, each with a distinct colour and icon:

Marker	Colour	Keyboard shortcut	When to use
Start	Blue	`S`	The instant the swimmer’s feet leave the block (or the push-off for backstroke)
Turn	Orange	`T`	The instant the swimmer’s hand (or feet) touches the wall at a turn
Breakout	Green	`B`	The first stroke cycle after a turn or start, when the head breaks the surface
Finish	Blue	`F`	The instant the swimmer’s hand touches the finish wall
15m / Underwater	Purple	`U`	The 15m mark — used to measure underwater distance off start or turns
Reaction	Red	`R`	Reaction time events (starter’s signal to start of movement)
Custom	Grey	`M`	Any other event you want to annotate (e.g. stroke error, equipment failure)

For a deeper reference, see Marker Types →

Adding a Marker

Open a race in the annotate screen
Pause the video on the exact frame you want to mark
Press the keyboard shortcut (e.g. T for a turn), or click + Add in the marker panel and choose the type

The marker is placed at the current playhead position and immediately appears in the panel and on the timeline.

Use the ← → arrow keys to step one frame at a time before placing a marker. At 60fps each frame is ~16ms, so frame accuracy matters for competitive splits.

Editing a Marker

Move a marker to a different frame

In the marker panel, click the marker you want to move
Scrub the video to the correct frame
Click Update Time (the clock icon next to the marker) or press Enter

Alternatively, drag the pin on the timeline left or right.

Rename a marker

Double-click the marker’s name in the panel to make it editable. Type the new name and press Enter.

This is useful for multi-athlete videos — for example, “Turn 1 – Athlete A” and “Turn 1 – Athlete B”.

Deleting a Marker

Hover over the marker row in the panel and click the trash icon, or
Click the marker to select it and press the Delete key

Deletions can be undone with Cmd + Z (Mac) or Ctrl + Z (Windows) — up to 20 marker actions. If you delete a Turn marker, the splits that depend on it will recalculate automatically.

Ordering and Grouping

Markers are always displayed in chronological order — sorted by timestamp, not by the order you created them.

If you have multiple swimmers in one video, use Custom markers with descriptive names to distinguish events. For a cleaner workflow with multi-swimmer footage, consider the Comparison feature instead.

Marker Notes

You can attach a text note to any marker:

Click the marker in the panel to expand it
Click the note field (pencil icon)
Type your observation — e.g. “Late touch, slightly crooked”
Press Enter to save

Notes appear in the exported CSV and in the shareable annotation link.