How to tell if a file contains classic IPTC or EXIF data

[Mac2]

In my application, I want to run the XMP2IPTC and XMP2EXIF arg files only when the target file already has IIM IPTC or EXIF metadata. Is there a reliable way to tell if a file has IPTC/EXIF data?

My first idea was to check for the mandatory EXIF version tag. But that was not fruitful because I found many files without this tag. For IPTC, I checked for the IPTC record version, which seemed to work well. But then I found files produced/modified by DAMinion and/or idimager, and these files had not IPTC record version although they contained IPTC tags like headline and caption-abstract.

Since I cache the output of ExifTool in a database, the ideal solution would be a lookup to check the existence of one or more tags to determine if the XMP2... arg files need to be run.

The only other idea I had so far would be to use the block tags -iptc and -exif (without -b) and to parse the output to see if these tags are included in the output. But I think this may be a performance hit (my application processes tens of thousands of files)  and I would have to reload the metadata of all files already processed.

Any ideas appreciated.

[Phil Harvey]

Is there a reliable way to tell if a file has IPTC/EXIF data?

Use -if "$exif:all" to only process files containing EXIF data.  You can do the same for IPTC.

But if you want to just check the extracted tags, you will have to extract with -G -a and look for any EXIF or IPTC tags.

The only other idea I had so far would be to use the block tags -iptc and -exif (without -b) and to parse the output to see if these tags are included in the output. But I think this may be a performance hit (my application processes tens of thousands of files)  and I would have to reload the metadata of all files already processed.

This would work too.  I would expect the performance hit to be minimal.

- Phil

[Mac2]

Hi, Phil

My application imports all metadata and runs ...2XMP.args files to produce rich XMP data before caching the result. Hence I cannot skip files as you suggested. Sorry to be not more clear in my question.

I need to find a way to tell after the import (from the database contents) if a file had IPTC/EXIF on import. At the time my application produces the ARG file to instruct ExifTool what to write, I include a call to the XMP2IPTC.ARG file to ensure MWG compliance (if the output file format supports IPTC):

...
-@
xmp2iptc.args
...


Could I use the -if logic here as well, to test for existing IPTC data in the output file and only then run the XMP2IPTC arg file?

[Phil Harvey]

I guess I don't understand.  The -if option can be used with any command.

- Phil

[Mac2]

I'm looking for something like

-xmp:descrioption=value
...
-if
$iptc:all
-@
xmp2iptc.args

output.jpg



Basically a way to tell ExifTool in an argfile to run xmp2iptc.arg only when the file has IPTC. I think -if can only be used to skip files based on a condition, but I want to write the XMP data and only run the xmp2iptc.arg file conditionally. Not sure if this is possible at all or if I have to implement this in my app.

[Phil Harvey]

If you want to always write some tags, but conditionally do something else, you need to execute a separate command, like this:

-xmp:description=value
...
-execute
-if
$iptc:all
-@
xmp2iptc.args
-common_args
output.jpg

- Phil

[ryerman]

Pardon the intrusion, but doesn't that last example contradict the documentation?

"-common_args

    Specifies that all arguments following this option are common to all executed commands when -execute is used. This and the -config option are the only options that may not be used inside a -@ ARGFILE. Note that by definition this option and its arguments MUST come after all other options on the command line."

Jim

[Phil Harvey]

Pardon the intrusion, but doesn't that last example contradict the documentation?

Woops!  My bad.  Good catch Jim.

- Phil

[Mac2]

If you want to always write some tags, but conditionally do something else, you need to execute a separate command, like this:

I understand, thanks. This would work.

But as I understand it, each execute causes ExifTool to reprocess the entire file (read/write). For typical RAW file sizes of 10 and 50 MB, or PSD/TIFF of usually 100 to 500 MB, this would probably cause performance problems. I will handle this in my application then. I know up-front and can pack everything into one execute for ExifTool.