Compressing time in GPX or FIT files

I'm looking for a tool or method to remove data points from a track file (FIT or GPX) and compress the time between remaining track points.

For example.... in a file that contains 1 second samples, remove every other sample and alter the time stamps on the data so that the remaining samples are marked as being 1 second apart.

If you know of a tool that does this, please point me in the right direction :-)

Thanks

0 Dresbo over 3 years ago

Can you explain a little about why you'd like to do that. Do you want to do it on the watch using fit files stored on the watch or could it be somewhere else (like on a server)?

For example, there are a number of js libraries which process fit/gpx files, but that would only be relevant if you can do it off the watch.

0 Jeff over 3 years ago in reply to Dresbo

This is for testing an app using the simulator.

I have real world data and would like to simulate higher speeds to test some logic.

0 jim_m_58 over 3 years ago in reply to Jeff

When playing back a big .fit for testing, I'll often you run them over night.

0 Dresbo over 3 years ago in reply to Jeff

I've used https://fit-route.pyrites.org.uk/ before to convert a gpx to a fit file which allows you to set the speed, but you may lose other data from the file when you first have to convert fit->gpx and then back again.

https://gpx.studio/ seems to have the ability to set the GPX file speed as well. Depends a little on what aspect of the fit file you want to test, but might be useful for you.

0 Jeff over 3 years ago in reply to Dresbo

Thanks.

I've tried using gps.studio. It seems to work but it produces records with a time difference between records of less than 00:00:01 which seems to make the simulator unhappy. When I looked closely at these records the time difference is not zero, but it's a fraction of a second. To make them work in the simulator I've had to manually edit the files... tedious.

I'll check out the other link you provided.

Thanks again.

0 Jeff over 3 years ago in reply to jim_m_58

It's not about big files in my situation. I actually want the data to appear as if the motion is faster... more distance covered in each second.

Thanks

0 jim_m_58 over 3 years ago in reply to Jeff

By "big" I meant long. The longer the recording, the bigger the files.

0 Alan.raceQs over 3 years ago

It's unlikely that there will be a tool for this.

You will have to edit the data yourself with a scripting language.

PHP for example will digest an XML file into an object that you can iterate over and edit or delete the <trkpt> elements to suit your needs.