Handling Dashcam Footage: Merge, Extract, Archive
Dashcams slice every drive into two-minute chunks — fine day to day, but when you need evidence or want to keep a scenic run, you must stitch segments, cut the key stretch, and archive without bloat. The whole pipeline runs in a browser.
What dashcam files look like
Loop recording is a storage strategy: fixed-length slices (commonly 1-5 minutes) written continuously, oldest overwritten when the card fills. Containers are typically TS or AVI (older models: 3GP), with H.264 inside — and crucially, segments from one device share identical encoding parameters, which is exactly what lossless merging requires.
Two habits before anything else: after an incident, stop the camera from writing immediately (pull the card or lock the files) so nothing gets overwritten; sort by the timestamped filenames and mark the segment range you need — one or two segments of context on each side.
Merging segments: same-source lossless splicing
Segments cut by one camera under one setting have identical codec parameters — merge them in order and the join is stream-copied: seconds fast, zero quality loss. Select files in timestamp order (sort in the file manager, then drag all in); wrong order scrambles the timeline.
If the merged output lands in TS or AVI, convert to MP4 on the spot — stream-copy shell swap, instantly playable on phones and platforms. Joints showing glitches mean the segments actually differ in spec (mixed settings or devices): switch to re-encode merging — slower, but the seams come out clean.
Cutting the key stretch and long-term archiving
Incident clips need margin: keep 10-15 seconds before and after the impact — the details that decide fault (signal, lane change, braking) live in the seconds prior. Precise cuts use the re-encode mode for frame-accurate points; if speed matters more, stream-copy with the cut placed where the car is stationary (at a red light) for a natural join.
The archive math: daily commutes are not worth keeping — save only notable trips. Record sources run high bitrates (10Mbps and up) over repetitive road scenery, so CRF 25 cuts well over half the size while plates and key details stay legible.