A few days ago I wrote about extracting GPX location data from the raw videos coming out of my A129 dashcam, and uploading to Mapillary. I was doing this one video at a time. A typical drive yields a lot of short videos, each 1, 5 or 10 minutes long depending on the settings. Some automation would be nice!

Mapper n76 suggested in the comments to my previous post to concatenate the short videos first and then process the resulting single video. I tried this following the instructions on the ffmpeg website, but I could not get exiftool to extract location data from the resulting longer video. So what I did instead was write a simple bash script that just loops over all MP4 files in the directory and does the GPX extraction and Mapillary processing / uploading for each file. Here’s the full script I used, which has the gpx.fmt file you need for exiftool baked in for convenience, but the loop itself is simply:

for f in *.MP4; do
    exiftool -m -p gpx.fmt -ee -ext mp4 -w %f.gpx $f
    mapillary_tools video_process_and_upload $f --geotag_source gpx --geotag_source_path ${f%%.*}.gpx --skip_process_errors
done

I found that I need --skip_process_errors because there’s usually one image extracted from the start or end of each video file that cannot be matched with a timestamp from the GPX file. I don’t care enough about one single image out of an entire sequence to try and figure out why, but I’m sure someone more determined than I could fix it :)