first time stamp is missing in gpx file extracted from mp4 (GoPro)

[Osman]

SG edit: Merged the two topics as I believe the answer for both is the same.

Hello to all,

does anyone else had the problem, that the gps data rate (10 per second) from the mp4 file of a GoPro was extracted with a lower resolution (1 per second)?

The command line I'm using is:
exiftool -p gpx.fmt -ee3 myvideo.MP4 > out.gpx

I'm using the exiftool Version 13.27_64 and a GoPro Hero11/Hero13 Black.

Thank you in advance!

[Osman]

Hello to all,

does anyone else had the problem, thatfor the first gps position, the time stamp is missing?

The command line I'm using is:
exiftool -p gpx.fmt -ee3 myvideo.MP4 > out.gpx

I'm using the exiftool Version 13.27_64 and a GoPro Hero11/Hero13 Black.

Thank you in advance!

output file:

Code Select Expand

<?xml version="1.0" encoding="utf-8"?>
<gpx version="1.0"
creator="ExifTool 13.27"
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>
<trkpt lat="xxx1" lon="yyy1">
</trkpt>
<trkpt lat="xxx2" lon="yyy2">
  <ele>466.435</ele>
  <time>YYY1-MMM1-DDD1THHH1:MMM1:SSS1.MSS1Z</time>
</trkpt>

[StarGeek]

I think that this thread might be relevant, the output shows that the first track point doesn't have a time stamp.

Specifically (emphasis mine)

ExifTool does extract all of the GPS from this file (18 samples per second).  The problem is that not all of the GPS is timestamped, and multiple GPS fixes are stored in what ExifTool is calling a single sub-document.

and

Unfortunately the -p option prints one line per sub-document, so you can't use it to see all of the GPS fixes.  Instead, you'll have to use some other ExifTool output format and process it yourself if you want a GPX file.

To summarize, the GoPro isn't saving a time stamp with every sample and you can get more detailed output by not using the -p (-printFormat) option to output as a GPX.