Telemetry Extractor
Pull the flight track out of a drone video or its telemetry file — DJI SRT, the subtitle track inside a DJI MP4/MOV, GPX, KML/KMZ, CSV or NMEA — and write CSV with UTM and real chainage, GPX, GeoJSON or KML. Nothing is uploaded: a multi-gigabyte video is read in place, and only its telemetry track is touched.
1. The video or telemetry file
Drop a file here, or choose one
DJI .SRT / .ASS · .MP4 / .MOV with a DJI subtitle track · .GPX · .KML / .KMZ · .CSV · NMEA .log
2. Design alignment — optional
Chainage,Latitude,Longitude,Description CSV (decimal or DMS), an Easting/Northing CSV with its zone, or a KML/KMZ centre line. With one, the CSV export carries a real chainage column — distance along the design line, not along the flight.
3. What to write
Needed for absolute elevation when the file records only height above the take-off point (Phantom, Air 2S, Mini). Matrice, Mavic 3 and Air 3 files carry absolute altitude themselves; GoPro and GPX are absolute already.
Showing the first 200 rows; the CSV download contains every row.
What this reads. DJI writes its telemetry as subtitles: a .SRT beside the clip, or a
subtitle track inside the MP4/MOV itself. The Phantom 4 / GO 4 layout (GPS (lon, lat, sats),
H, D), the Air 2S / Mini / Mavic 2 bracket layout and the Mavic 3 / Air 3 / Matrice
layout (rel_alt / abs_alt) are all recognised, including the firmware that spells
"longtitude". A video is opened in place: the index and the subtitle samples are read through the browser's own
file access — a 2.7 GB Phantom clip needs about 60 KB — and the picture is never touched or uploaded.
GPX, KML/KMZ (gx:Track, LineString or placemarks), CSV with latitude/longitude columns and NMEA 0183 logs read too.
What it writes. Times are UTC; a DJI file's wall clock is local with no zone marker, so the zone above is
applied and recorded. Positions are interpolated at the output rate; every other channel is the last recorded
value at that instant, never an invented in-between one. Elevation from a DJI file is height above the take-off
point unless the aircraft wrote abs_alt — the export says so. Chainage is the position
projected onto the design alignment in UTM grid, with the offset reported on the ground; distance along the
flight is a different number and is in distance_m. Derived channels are computed over a 1.5-second
window and marked as computed; nothing time-based is derived from a file that carried no clock.
This is the same engine as BTPL's GeoVideo Telemetry Studio, held to its exports on the same real files.
Survey video, delivered to the standard
BTPL records, processes and delivers chainage-referenced survey video for highways and railways — telemetry overlay, inspection registers and GIS-ready tracks.