ExifTool Forum

ExifTool => Newbies => Topic started by: yawnbiter on July 05, 2021, 10:06:19 PM

Title: Change output GPS time interval using gps.fmt
Post by: yawnbiter on July 05, 2021, 10:06:19 PM
Hi all,

I've just received an MP4 file taken from a gopro7 and I've been using the following command to extract the GPS coordinates:

exiftool -ee -p gpx.fmt FILE.mp4 > FILE.gpx

I've noticed that I'm only getting a GPS point for every 1second, whereas the framerate is captured at 30fps.
Is there a setting I can either change in the fmt file or commandline to ensure that I export the gps coordinate for every frame?

Thanks!
Title: Re: Change output GPS time interval using gps.fmt
Post by: StarGeek on July 06, 2021, 01:03:45 AM
Quote from: yawnbiter on July 05, 2021, 10:06:19 PM
I've noticed that I'm only getting a GPS point for every 1second, whereas the framerate is captured at 30fps.

According to Phil's answer in this post (https://exiftool.org/forum/index.php?topic=11921.msg64328#msg64328), the GPS data is not synchronized to the frame rate.  Also, here (https://exiftool.org/forum/index.php?topic=11921.msg64347#msg64347) in that same thread, there is only one GPS timestamp approximately, but not exactly, every second.

QuoteIs there a setting I can either change in the fmt file or commandline to ensure that I export the gps coordinate for every frame?

Try listing the GPS data with this command to see if there is more GPS coordinates.  My understanding of that thread is that there should be more coordinates per second, but only one timestamp approximately every second
exiftool -G1 -a -s -ee -gps* FILE.mp4
Title: Re: Change output GPS time interval using gps.fmt
Post by: yawnbiter on July 06, 2021, 09:47:13 PM
Thanks SG,

Yes, I ran that command and I definitely see that I have intermediate GPS coords in between the timestamped records - an additional 18 per second, the same as the referenced post.

Now that I know how it works, I'll be able to develop something to merge the information together and perform analysis of the GPS & Time data.

Thanks for your help!