Count how often a light turns on or off in archive news footage
0:40PD · Universal Newsreels
Proof frames
Tool calls
track_region_events
Arguments
{
"source": "$CLIP",
"start_sec": 0,
"end_sec": 39.91,
"region": {
"x": 0.59025,
"y": 0.082,
"width": 0.182,
"height": 0.176
},
"sample_fps": 2
}
Result
{
"ok": true,
"data": {
"region": {
"x": 0.59025,
"y": 0.082,
"width": 0.182,
"height": 0.176
},
"start_sec": 0,
"end_sec": 39.91,
"sample_fps": 2,
"sample_count": 80,
"temporal_resolution_sec": 0.5,
"scan_segments": [
{
"start_sec": 0,
"end_sec": 39.91,
"sample_count": 80
}
],
"transitions": [
{
"from_timestamp_sec": 3,
"timestamp_sec": 3.5,
"from_timestamp_provenance": {
"requested_timestamp": 3,
"decoded_timestamp": null,
"timestamp_delta": null
},
"timestamp_provenance": {
"requested_timestamp": 3.5,
"decoded_timestamp": null,
"timestamp_delta": null
},
"change_score": 0.233852,
"mean_abs_diff": 0.1894,
"changed_fraction": 0.316406,
"evidence_moments": {
"before": {
"timestamp_sec": 3,
"timestamp_provenance": {
"requested_timestamp": 3,
"decoded_timestamp": null,
"timestamp_delta": null
}
},
"after": {
"timestamp_sec": 3.5,
"timestamp_provenance": {
"requested_timestamp": 3.5,
"decoded_timestamp": null,
"timestamp_delta": null
}
}
},
"rank": 1
},
{
"from_timestamp_sec": 6.5,
"timestamp_sec": 7,
"from_timestamp_provenance": {
"requested_timestamp": 6.5,
"decoded_timestamp": null,
"timestamp_delta": null
},
"timestamp_provenance": {
"requested_timestamp": 7,
"decoded_timestamp": null,
"timestamp_delta": null
},
"change_score": 0.238314,
"mean_abs_diff": 0.194161,
"changed_fraction": 0.320312,
"evidence_moments": {
"before": {
"timestamp_sec": 6.5,
"timestamp_provenance": {
"requested_timestamp": 6.5,
"decoded_timestamp": null,
"timestamp_delta": null
}
},
"after": {
"timestamp_sec": 7,
"timestamp_provenance": {
"requested_timestamp": 7,
"decoded_timestamp": null,
"timestamp_delta": null
}
}
},
"rank": 2
},
{
"from_timestamp_sec": 9.5,
"timestamp_sec": 10,
"from_timestamp_provenance": {
"requested_timestamp": 9.5,
"decoded_timestamp": null,
"timestamp_delta": null
},
"timestamp_provenance": {
"requested_timestamp": 10,
"decoded_timestamp": null,
"timestamp_delta": null
},
"change_score": 0.234973,
"mean_abs_diff": 0.189941,
"changed_fraction": 0.318604,
"evidence_moments": {
"before": {
"timestamp_sec": 9.5,
"timestamp_provenance": {
"requested_timestamp": 9.5,
"decoded_timestamp": null,
"timestamp_delta": null
}
},
"after": {
"timestamp_sec": 10,
"timestamp_provenance": {
"requested_timestamp": 10,
"decoded_timestamp": null,
"timestamp_delta": null
}
}
},
"rank": 3
},
{
"from_timestamp_sec": 12.5,
"timestamp_sec": 13,
"from_timestamp_provenance": {
"requested_timestamp": 12.5,
"decoded_timestamp": null,
"timestamp_delta": null
},
"timestamp_provenance": {
"requested_timestamp": 13,
"decoded_timestamp": null,
"timestamp_delta": null
},
"change_score": 0.234633,
"mean_abs_diff": 0.189943,
"changed_fraction": 0.317627,
"evidence_moments": {
"before": {
"timestamp_sec": 12.5,
"timestamp_provenance": {
"requested_timestamp": 12.5,
"decoded_timestamp": null,
"timestamp_delta": null
}
},
"after": {
"timestamp_sec": 13,
"timestamp_provenance": {
"requested_timestamp": 13,
"decoded_timestamp": null,
"timestamp_delta": null
}
}
},
"rank": 4
},
{
"from_timestamp_sec": 15.5,
"timestamp_sec": 16,
"from_timestamp_provenance": {
"requested_timestamp": 15.5,
"decoded_timestamp": null,
"timestamp_delta": null
},
"timestamp_provenance": {
"requested_timestamp": 16,
"decoded_timestamp": null,
"timestamp_delta": null
},
"change_score": 0.234711,
"mean_abs_diff": 0.189801,
"changed_fraction": 0.318115,
"evidence_moments": {
"before": {
"timestamp_sec": 15.5,
"timestamp_provenance": {
"requested_timestamp": 15.5,
"decoded_timestamp": null,
"timestamp_delta": null
}
},
"after": {
"timestamp_sec": 16,
"timestamp_provenance": {
"requested_timestamp": 16,
"decoded_timestamp": null,
"timestamp_delta": null
}
}
},
"rank": 5
},
"…trimmed 3 more"
],
"event_count": 8,
"uncertain": false,
"incomplete": false,
"uncertainty_reason": null
}
}
Question and answer
- Question
- How many times does the light turn on or off in this video?
- Answer
- The tool counts 8 state changes in the box over the clip; each switch on and each switch off is one change.
Check passedanswer 8, expected 8 (tolerance 0)
How it was checked
- Truth from
- constructed
- Fixed at
Planted by this recipe before any tool ran: a dark box (91 by 66 px, left edge at 227 px, top edge at 18 px) was drawn over the picture for the whole 40 s clip, and a yellow light inside it was switched on and off 4 times, at the toggle times 3.25, 6.75, 9.75, 12.75, 15.75, 18.75, 21.75, 25.25 s, with ffmpeg. The truth is 8 state changes (each switch on and each switch off counts once), fixed here before the run. The call samples 2 frames per second over the clip with the box inset by 0.1 of its size on each side.
A script drew a dark box over the picture and switched a light in it on and off 4 times at set times, so the count is those planted changes (each on and each off counts once) and only the box was checked.
Try it yourself
Use agentic-video to count how often the light in my video turns on or off. Run track_region_events on the box at x 0.590, y 0.082, width 0.182, height 0.176 (fractions of the frame) from 0 to 39.91 seconds, sampling 2 frames per second. Tell me the event count, then show me the first change. Use my own file.
- Get the .mcpb file and open it in Claude Desktop.
- Or:
pip install agentic-video
Clip and licence
- Licence
- PD
- Author
- Universal Newsreels
- Source
- commons.wikimedia.org
This work has been released into the public domain by its copyright holder, Universal Pictures. This applies worldwide.