Export GPS Points from Dash Cam with FFMPEG?

Question

I have a Garmin Dash Cam 35 that outputs an MP4 that appears to have the GPS data I need encoded in the MP4. I've seen claims that they're using SEI messages to do this, but using Intel Video Analyzer I'm not able to see those types of SEI messages.

Does anyone know if they're likely using SEI messages or if I can export those SEI messages from the video using ffmpeg or any other command line tool? Even if they're just in binary I may be able to figure out the structure.

Edit: Sample video can be downloaded here (60MB): https://drive.google.com/file/d/0B2o2cryfiWzANTJQdVJuNjY5SzQ/view?usp=sharing

This question is helpful: http://gis.stackexchange.com/questions/157114/how-to-extract-gps-information-from-garmin-cam-20-video-files — Steve, Nov 14 '16 at 01:58
The file does have SEI NALs attached to every frame, but their format is different from described in answers in GIS link above, it's just 14 bytes per NAL unit. — Roman R., Nov 29 '16 at 20:12

score 0 · Answer 1 · answered Jul 25 '21 at 15:52

Using exiftool, you can extract the GPS data from this video into GPX or KML track log.

First you would need to either copy/paste the gpx.fmt file from here or downloaded it from GitHub. That GitHub link also has a fmt file to create a KML file if desired. Then you run this exiftool command
exiftool -p /path/to/gpx.fmt -ee File.MP4 >out.gpx

Export GPS Points from Dash Cam with FFMPEG?

1 Answers1