Browse documentationMedia markers
Point reviewers to the time range that matters
Markers annotate a point or time range in an audio or video item without editing the media. They are stored in the Dataset item configuration, frozen into the published Dataset version, projected through the blind assignment contract, and rendered only by review modes that support time-based inspection.
| Input | Meaning | Normalized result |
|---|---|---|
| 2 | Point at two seconds | start 2.0, end 2.5 |
| [4, 6] | Range from four to six seconds | start 4.0, end 6.0 |
| { time, label } | Named point | Point plus optional label, color, and icon |
| { start, end, label } | Named range | Range plus optional label, color, and icon |
Validation rules
Marker times are seconds, must be finite and non-negative, and a range must end at or after its start. Labels and icons are length-limited text. Colors accept a restricted CSS color form or color-auto; unsafe CSS and markup are rejected.
Markers belong to a source folder, so every supported stimulus in that item receives the same attention guidance. Use separate source folders when different conditions require different annotated moments.
Video behavior
A marker rail appears with the custom video controls. A point occupies a narrow segment; a range spans its duration. When playback enters an active marker, the player shows its icon and optional label without covering the central comparison area.
Marker UI is suppressed in native fullscreen because browser controls cannot preserve the same blind, synchronized overlay contract there. The marker data remains unchanged and reappears after leaving fullscreen.
Audio behavior
Audio markers use a time rail or waveform band, depending on the available player surface. Labeled markers expose their description to pointer and keyboard users. Audio ignores the active video overlay icon but keeps the marker label accessible.
Markers guide attention, not the answer
A marker says where to inspect; it does not label a candidate as correct or low quality. Golden Control answers and quality anchors use separate restricted fields. This separation prevents an ordinary Dataset annotation from leaking the intended result into blind review.
Per-item config
Mark one point and one time range
{
"title": "Motion artifact review",
"question": "Which video handles the transition better?",
"description": ["Judge temporal stability before texture."],
"markers": [
{ "time": 2.0, "label": "Transition begins" },
{
"start": 4.5,
"end": 6.0,
"label": "Inspect edge stability",
"color": "#d97706",
"icon": "!"
}
]
}