Delete Date tags if set as "0000:00:00 00:00:00"

[vicmarto]

Hello.

I have one weird mp4 file with this dates sets:

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$ exiftool -s -time:all -a -G0:1 PDPQ8212.MP4
[File:System]   FileModifyDate                  : 2019:08:14 15:50:22+02:00
[File:System]   FileAccessDate                  : 2019:08:29 23:15:24+02:00
[File:System]   FileInodeChangeDate             : 2019:08:29 23:15:24+02:00
[QuickTime]     CreateDate                      : 0000:00:00 00:00:00
[QuickTime]     ModifyDate                      : 0000:00:00 00:00:00
[QuickTime:Track1] TrackCreateDate              : 0000:00:00 00:00:00
[QuickTime:Track1] TrackModifyDate              : 0000:00:00 00:00:00
[QuickTime:Track1] MediaCreateDate              : 0000:00:00 00:00:00
[QuickTime:Track1] MediaModifyDate              : 0000:00:00 00:00:00
[QuickTime:Track2] TrackCreateDate              : 0000:00:00 00:00:00
[QuickTime:Track2] TrackModifyDate              : 0000:00:00 00:00:00
[QuickTime:Track2] MediaCreateDate              : 0000:00:00 00:00:00
[QuickTime:Track2] MediaModifyDate              : 0000:00:00 00:00:00

There is one easy way to check for Date tags (all of them) that are set to "0000:00:00 00:00:00" and just... delete them?

Thanks.

[Phil Harvey]

None of those tags are deletable since they are part of binary data structures.  Essentially, the only way to "delete" these values is to set them to zero, which is what they already seem to be set to.

I should probably document this somehow, but any tag listed with an "Index" instead of a "Tag ID" in the Tag Name documenation is part of a binary data structure, and hence not individually deletable.

- Phil

Edit: I have updated the main page of the tag name documentation to add this note: "(Note that writable tags within binary data blocks are not individually deletable, and the alternative is to set them to a value of zero.)"

[StarGeek]

edit: I'm too bullheaded not to post anyway just because Phil beats me by 40 seconds

I do not believe that the time data in video files can be removed completely.  If you run exiftool with a command like
exiftool -CreateDate= -ModifyDate= file.mp4
you'll see that doing so just sets the timestamps to 0000:00:00 00:00:00

Even FFMpeg just sets the values to 0 when you run a command to remove metadata
ffmpeg -i in.mp4 -map_metadata -1 -c:v copy -c:a copy out.mp4

[vicmarto]

Thanks to both, I see now where is the problem.

In that case, how can I avoid using this "0000:00:00 00:00:00" dates by mistake when mass tagging my files? Maybe something with -if?

Is this correct?:

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-if 'not $CreateDate cmp 0 and not $CreationDate cmp 0'

[Phil Harvey]

edit: I'm too bullheaded not to post anyway just because Phil beats me by 40 seconds

[Phil Harvey]

I can't give a comprehensive answer without seeing your command, but I would use an advanced formatting expression, like this:

'-createdate<${createdate;$_ = undef if /^0000/}'

The advantage is that any other tags you want could still be copied.

- Phil

[StarGeek]

Other options, since Phil is still faster than me.

That cmp won't work, as any time stamp is going to be greater than 0.  You'll have to use string comparison operators.

You're probably going to have to use eq (equal) or ne (not equal)
-if '$CreateDate ne "0000:00:00 00:00:00" and $CreationDate ne "0000:00:00 00:00:00" '
or gt (greater than) would work as well
-if ' not $CreateDate gt "0000:00:00 00:00:00" and not $CreationDate gt "0000:00:00 00:00:00" '

Edit:  Actually, since I believe that the video timestamps can't be earlier than 1970:01:01, you could use this to have a more compact command
-if ' not $CreateDate gt "0" and not $CreationDate gt "0" '

[StarGeek]

'-createdate<${createdate;$_ = undef if /^0000/}'

Ah, I get that.  I like that, though it might be confusing for new users. 

[vicmarto]

Wow, really impressed with this forum, really. Both solutions worked. Thanks!!!

One more (unrelated) question please. I'm beginning to experiment with -if. Is this correct?:

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-if 'not defined $SubSecTime and not defined $SubSecTimeDigitized and not defined $SubSecTimeOriginal' \

I only want to edit files that don't have any of these 3 tags.

[Phil Harvey]

That is correct.

- Phil

[kennethmac2000]

I can't give a comprehensive answer without seeing your command, but I would use an advanced formatting expression, like this:

'-createdate<${createdate;$_ = undef if /^0000/}'

The advantage is that any other tags you want could still be copied.

- Phil

As far as I can tell, this only works if the API option QuickTimeUTC is not set, as otherwise a binary zero value gets converted to 1904-01-01 00:00:00. One could match on /^1904/ in that case, but that feels rather less elegant.

However, I need to use the API option QuickTimeUTC elsewhere in the same exiftool call.

Is it possible to apply an API option like QuickTimeUTC only to part of an exiftool call?

Eg, in the command exiftool -if '<expression>' '-y<z', I don't want QuickTimeUTC to be applied to the evaluation of <expression>, but I do want it to be applied to '-y<z' (or vice versa).

[StarGeek]

Is it possible to apply an API option like QuickTimeUTC only to part of an exiftool call?

No.  You would need to run it separately or split the command with an -execute option, which basically the same.

[kennethmac2000]

Is it possible to apply an API option like QuickTimeUTC only to part of an exiftool call?

No.  You would need to run it separately or split the command with an -execute option, which basically the same.

But unless I'm missing something, if I ran, say exiftool -if 'XXX' -execute YYY -common_args ., that wouldn't help, because exiftool would first execute every iteration of "-if 'XXX'" (effectively sending the result of each evaluation of that conditional into a black hole), and it would then execute every iteration of "YYY" (unconstrained by the conditional).

I need to intercept each iteration of the 'for loop' and then do something in another command depending on the initial result, but, again, unless I'm missing something, that's not possible with exiftool 'out of the box'.

As far as I can see, I would have to write some shell code to iterate through the contents of a directory and call exiftool -if 'XXX' on one file at a time, looking for either a 0 or a 2 exit status, and then in the case of a 0, making a second call to exiftool, also on that single file.

Am I right? (Or if not can anyone suggest some pseudocode that does what I want with a single exiftool call?)

[StarGeek]

But unless I'm missing something, if I ran, say exiftool -if 'XXX' -execute YYY -common_args ., that wouldn't help, because exiftool would first execute every iteration of "-if 'XXX'" (effectively sending the result of each evaluation of that conditional into a black hole), and it would then execute every iteration of "YYY" (unconstrained by the conditional).

Which is why I said it's basically the same as running two commands.

I need to intercept each iteration of the 'for loop' and then do something in another command depending on the initial result, but, again, unless I'm missing something, that's not possible with exiftool 'out of the box'.

Correct

As far as I can see, I would have to write some shell code to iterate through the contents of a directory and call exiftool -if 'XXX' on one file at a time, looking for either a 0 or a 2 exit status, and then in the case of a 0, making a second call to exiftool, also on that single file.

You don't want to call exiftool on every file one at a time unless you want the processing time to be increased by a magnitude. This is Common Mistake #3.

Exiftool's biggest performance hit is the startup time and running exiftool once on every file twice will take significantly longer than running a two commands on all the files and filtering with the -if option.

[kennethmac2000]

You don't want to call exiftool on every file one at a time unless you want the processing time to be increased by a magnitude. This is Common Mistake #3.

Exiftool's biggest performance hit is the startup time and running exiftool once on every file twice will take significantly longer than running a two commands on all the files and filtering with the -if option.

Yes, I assumed this.

But then I still have two (related) questions:
1) What am I getting the first exiftool call to do (given that it's not actually going to modify the files in question at this stage)? In pseudocode terms, IF x THEN what?
2) How am I passing the result of the first call (for each file) to the second call? Is there a canonical way of doing this?