Wrong GPS date in CAMM metadata

[Kajuna]

Hi,

I'm extracting GPS data from multiple cameras. Some of them use the CAMM protocol (as far as I know).

With at least one of them (LabPano's Pilot Era) the GPS timestamps seem completely wrong. The time is correct, which seems to indicate good GPS time data, but the dates are off (10 years and some days off).

I'm not sure if this could be a problem with the way camera records the data or if there could be some error when parsing it. The date seems correct with other camera models.

Here's my command:

-api largefilesupport -ee -u -p '{"date":"$gpsdatetime#","lat":$gpslatitude#,"lon":$gpslongitude#,"alt":$gpsaltitude#}' video.mp4

And the resulting lines look like:

{"date":"2011:04:02 20:32:18.222569Z","lat":40.768945,"lon":-77.8826065,"alt":372.899993896484}

(but the video is from 2021)

I'm using ExifTool 12.23

I can provide a link to the problematic sample file privately (it's about 800MB)

Thank you

[Phil Harvey]

Send me the file and I'll take a look (philharvey66 at gmail.com)

- Phil

[Phil Harvey]

Sorry for the delay.

I got the file, thanks.  The problem is that other applications don't use a consistent epoch for the timestamps stored in the camm6 metdata.  According to the documentation I was able to find, it seems like the time zero should be Jan 6, 1980 (the GPS epoch), but some apps use Jan 1, 1970 (the Unix epoch).  All of my samples up until now used the Unix epoch, so "fixing" this would break the times of all these files.

I'll apply a smart patch that will compare the video CreateDate to the GPSDateTime, and adjust for the GPS epoch only if there is a large enough difference.

ExifTool 12.27 will contain this patch.

Thanks for this report.

- Phil

P.S. You wouldn't believe how many patches ExifTool contains just to handle other apps that write things incorrectly.

[Kajuna]

Sorry for the delay.

I got the file, thanks.  The problem is that other applications don't use a consistent epoch for the timestamps stored in the camm6 metdata.  According to the documentation I was able to find, it seems like the time zero should be Jan 6, 1980 (the GPS epoch), but some apps use Jan 1, 1970 (the Unix epoch).  All of my samples up until now used the Unix epoch, so "fixing" this would break the times of all these files.

I'll apply a smart patch that will compare the video CreateDate to the GPSDateTime, and adjust for the GPS epoch only if there is a large enough difference.

ExifTool 12.27 will contain this patch.

Thanks for this report.

- Phil

P.S. You wouldn't believe how many patches ExifTool contains just to handle other apps that write things incorrectly.

Really appreciated!

I know what you mean. I've had to implement very similar patches when parsing other file formats. I'm amazed at the amount of devices you are able to support