Toyota Dashcam metadata

[DSDunbar]

I have a Toyota Dash Cam (DASH CAM VIEWER vs. 1.4.1 DENSO TEN Ltd.). It apparently uses GNU software (FFmpeg). I can't figure out how to extract the GPS coords & timestamp using either ExifTool, FFmpeg, or FFprobe. I have little experience using these particular video tools or for processing video files. I'd like to extract the metadata for subsequent processing using a python script I'm writing. Any suggestions on how to proceed?

[StarGeek]

Have your tried the instructions under Inverse Geotagging?  You need to create a gpx.fmt file, either by copying the text shown there or downloading from Github.

[DSDunbar]

Running:

exiftool -p gpx.fmt -ee3 sample.mp4 > out.gpx

using the gpx.fmt file from the linked page you provided produces the following terminal output:

Warning: Truncated '\xe6,\xe1\xab' data - sample.mp4

and the following content in out.gpx:

<?xml version="1.0" encoding="utf-8"?>
<gpx version="1.0"
creator="ExifTool 12.30"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns="http://www.topografix.com/GPX/1/0"
xsi:schemaLocation="http://www.topografix.com/GPX/1/0 http://www.topografix.com/GPX/1/0/gpx.xsd">
<trk>
<number>1</number>
<trkseg>
</trkseg>
</trk>
</gpx>

[StarGeek]

Can you share a short sample, preferably one with enough movement so that the GPS coordinates change.  Odds are it would be too big to attach to a post here, so a Dropbox or Google drive link  or similar would be best.

[DSDunbar]

Here is a link on Dropbox to a sample mp4 file (approx. 51s long) generated by my Dash Cam:

https://www.dropbox.com/s/my32xf3d232l8qn/sample.mp4?dl=0

Any help in pulling out the GPS data would be greatly appreciated

[Phil Harvey]

I can see where the GPS is stored, but this is a format I haven't seen before.  I will see about decoding this, but it may take me a day or two before I can look more closely at this.

- Phil

[DSDunbar]

Much appreciated. For completeness - I am on a Mac mini (2018) running macOS 11.6 with 64 GB of RAM

[Phil Harvey]

Unfortunately I think I was wrong.  This doesn't look like GPS in the 'udat' chunk (as I have seen for some other dashcams).  Every second number increases by about 750000 (likely a timestamp of some sort), and the values in between all range around 3200 (don't know what this is). Here are the first few numbers stored in the 'udat' chunk:

Code Select Expand

      0
     52
  66048
   8192
810084
   3228
1528564
   3148
2251011
   3229
2973267
   3149
3709218
   3230
4446960
   3152
5168000
   3200
5908232
   3160
6632200
   3224
7371847
   3161
8132610
   3230
8823869
   3139
9565288
   3224
10307394

There is also an unknown trailer starting at 0x10200, but it looks to be encrypted somehow and I can't see any coordinates there.

- Phil

[DSDunbar]

Thanks for your efforts. I will attempt to get info on the mp4 format from the manufacturer.