Compare FileModifyDate and DateTimeOriginal within 3 seconds

[lei]

Hi there!

I'm trying to use ExifTool to list .jpg files in a folder where the FileModifyDate and DateTimeOriginal differ by no more than 3 seconds.

I tried using -if to compare the two tags, like this:

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exiftool -if "abs($FileModifyDate - $DateTimeOriginal) <= 3" -filename -FileModifyDate -DateTimeOriginal -ext jpg .
But it doesn't return any results, even though I have files where the time difference is clearly less than 3 seconds. I suspect the problem is that these tags are strings and can't be compared directly like numbers.

Is there a correct way to compare these two timestamps with a tolerance (e.g. 3 seconds)? Or should I use another method?

I'm on Windows 10, using ExifTool version 12.92.

Thanks in advance!

[Phil Harvey]

$datetimeoriginal is a string as you suspected.

Unless you use the -d %s option, then it is converted to seconds since 1970, which you can use in your expression.

- Phil

[lei]

Thanks, Phil. Based on your reply, I understand that -d %s only affects the output, not the internal comparison.

Could you please show me the exact ExifTool command that lists JPG files where FileModifyDate and DateTimeOriginal differ by no more than 3 seconds? I want to do this entirely inside ExifTool, without using shell, awk, or PowerShell.

Thanks in advance!

[greybeard]

How about:

exiftool -if 'abs(${FileModifyDate;DateFmt("%s")}-${DateTimeOriginal;DateFmt("%s")}) < 4 ' -FileName -FileModifyDate -DateTimeOriginal -ext jpg -T .

This is MacOS you might need to switch single and double quotes on Windows

[StarGeek]

Thanks, Phil. Based on your reply, I understand that -d %s only affects the output, not the internal comparison.

No. This changes the value of the tag completely in the command it is used.

Example. This is a simplified version of @greybeard's command using only the -d (-dateFormat) option rather than the DateFmt helper function. Also, the hashtag version of the -n (--printConv) option is used to display the unmodified values.

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C:\>exiftool -G -a -s -DateTimeOriginal -FileModifyDate y:\!temp\Test4.jpg
[EXIF]          DateTimeOriginal                : 2025:04:12 12:00:00
[File]          FileModifyDate                  : 2025:04:12 12:00:02-07:00

C:\>exiftool -G -a -s -d %s -if "abs($FileModifyDate-$DateTimeOriginal) < 4 " -FileName -FileModifyDate -DateTimeOriginal -FileModifyDate# -DateTimeOriginal# y:\!temp\Test4.jpg
[File]          FileName                        : Test4.jpg
[File]          FileModifyDate                  : 1744484402
[EXIF]          DateTimeOriginal                : 1744484400
[File]          FileModifyDate                  : 2025:04:12 12:00:02-07:00
[EXIF]          DateTimeOriginal                : 2025:04:12 12:00:00
Also, make sure you're using CMD and not PowerShell. PowerShell's quoting rules are different from every other command line.

[lei]

Thanks a ton, you guys are awesome! Phil's method is definitely spot-on; I just messed up by skipping a few options I shouldn't have, which led to some syntax errors. Greybeard's approach is no doubt correct as well. StarGeek's explanation really helped me understand a few proper uses better. Big thanks to all of you!

[greybeard]

[This is a simplified version of @greybeard's command using only the -d (-dateFormat) option

The simplified option is always the better option

[lei]

[This is a simplified version of @greybeard's command using only the -d (-dateFormat) option

The simplified option is always the better option

Absolutely, when there are a bunch of tags in the command, simpler is better. But with just one or two, both methods work great. Thank you once again.

[lei]

Dear Experts,

Now, I want to add something more.

Could anyone please tell me how to calculate the time difference between two timestamps in JPG files?

I want to find the time difference between -DateTimeOriginal and -FileModifyDate in a format like this:

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Filename              DateTimeOriginal        FileModifyDate          Difference 
20250423_164706.jpg    2025:04:23 16:47:06      2025:04:23 16:47:44      38 sec 
20250423_164809.jpg    2025:04:23 16:48:09      2025:04:23 16:48:10      1 sec 
The first column is the filename, the second is -DateTimeOriginal, the third is -FileModifyDate, and the fourth is the time difference that I want to calculate.

Thanks in advance!

[StarGeek]

The cleanest solution is to create a user-defined tag to do this. To do this directly on the command line would be messy, and you would have to use the -p (-printFormat) option.

I'm also assuming you want the absolute difference between the two values.

Here's a config file that will calculate the difference and output it as a tag called MyTimeDiff.

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%Image::ExifTool::UserDefined = (
    'Image::ExifTool::Composite' => {
#------------------------------------------------------------------------------
        MyTimeDiff => {
            Require => {
                0 => 'DateTimeOriginal',
                1 => 'FileModifyDate',
            },
            ValueConv => q{
                return (abs(GetUnixTime($val[0])-GetUnixTime($val[1])));
            },
        },
#------------------------------------------------------------------------------
    },
);

1;  #end
If you have an .ExifTool_config file, you can cut the section between the bars and place that in the config file under the 'Image::ExifTool::Composite' => { line.

Example

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C:\>exiftool -config MyTimeDiff.config -G1 -a -s -DateTimeOriginal -FileModifyDate -MyTimeDiff y:\!temp\Test4.jpg
inconfig
[ExifIFD]       DateTimeOriginal                : 2025:04:23 08:12:41
[System]        FileModifyDate                  : 2025:04:23 08:00:00-07:00
[Composite]     MyTimeDiff                      : 761
This would simplify your original comand with
-if "$MyTimeDiff< 4"

Using the -p option, your command would be
exiftool -p "$Filename  $DateTimeOriginal $FileModifyDate ${DateTimeOriginal;$_=abs(GetUnixTime($_)-GetUnixTime($self->GetValue('FileModifyDate')))} /path/to/files/

Example

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C:\>exiftool -p "$Filename  $DateTimeOriginal $FileModifyDate ${DateTimeOriginal;$_=abs(GetUnixTime($_)-GetUnixTime($self->GetValue('FileModifyDate')))}" y:\!temp\Test4.jpg
Test4.jpg  2025:04:23 08:12:41 2025:04:23 08:00:00-07:00 761

[lei]

Thanks a lot for your reply! Your solution works perfectly and helped me understand how ExifTool's expression syntax works, especially the use of $_ and $self->GetValue(...). I was wondering why I couldn't just use $FileModifyDate directly, and your solution made that clear. That really saved me a lot of time — thanks again!

[StarGeek]

The only place I can think of off hand that you can process two separate tags directly is in the -if option.

[lei]

StarGeek!

Thanks again for your earlier post — I've been going over it and thinking things through before replying. Just one follow-up if you don't mind: when you mentioned that the only place where two separate tags can be processed directly is in the -if option, could you clarify a bit what makes -if different in this case? Were you referring mainly to logical comparisons like $tag1 ne $tag2, or is there more that -if allows compared to, say, -p expressions? I'm still learning my way around ExifTool, so any extra insight would be much appreciated.

[Phil Harvey]

I don't know what StarGeek meant by this, but the only real difference between -if and -p and expressions in -tagsfromfile arguments is that the -if condition is evaluated as a Perl expression and the others aren't.

- Phil

[StarGeek]

Yes, Phil, that's exactly what I meant. Thanks for clarifying.