Comparing changes

I have a group action consisting of 121 actions [steps]

Although some of it have been used by me before and the new one were tested thoroughly, I'm afraid that there could be some glitch. And if I now run this on wall of my files it could result in some major data lost, to be discovered months from now

So I wonder if there is some [external?] way of comparison of tag values. Whole operation would have to go something like this:
1] Load all of the files
2] Arrange them in Mp3tag by size [because it won't change after running my action and it is the most individual value of the file that I can think of]
3] Export all tag fields
4] Execute action
5] Export all tag fields
6] Compare the second export with the first one

But already I can imagine that I would want to limit the comparison data and / or outcome report

Limiting the comparison can be done it Mp3tag, simply by not exporting certain fields

And also "limiting" the report could also be done easily: by showing only cases [values from files] where changes did occur

What software could I possibly use for the latter?

search the internet for "diff", e.g.
http://gnuwin32.sourceforge.net/packages/diffutils.htm

WinMerge
http://winmerge.org/?lang=ru
http://winmerge.org/?lang=de

DD.20150723.2000.CEST

You may consider to let Mp3tag calculate a MD5 hash value for each file.

  • MD5-Hash of the audio part of the file: %_md5audio%
  • MD5-Hash of the entire file: %_md5%

Twins-files with identical music data part ...

  • should have the same %_md5audio% hash value;
  • but with different tag data ... should have different %_md5% hash values.

Mp3tag can calculate the MD5 hash values only when exporting data, so run a simple export script ...

$filename($getEnv('TEMP')'\Mp3tag.Hashes.txt',UTF-16)$loop(%_path%)%_crc%'|'%_md5%'|'%_md5audio%'|'%_path% $loopend()

Afterwards use the converter "Textfile - Tag" ...
and import the needed data into the files into a dedicated helper tag-field, ...
and set up a column in Mp3tag listview.

Action for importing ...

Begin Action Group MyMusic Import#&5 Import DD_MD5AUDIO MD5 CRC32 from textfile

Action #1
Actiontype 14: Import text file
Field __: TMP_TEXT
Filename: $getEnv('TEMP')'\Mp3tag.Hashes.txt'

Action #2
Actiontype 5: Format value
Field ______: TMP_TEXT
Formatstring: $regexp(%TMP_TEXT%,'(?:.\n|^|\A)(.+?)|(.+?)|(.+?)|('$replace(%_path%,'','\\')')(?:\r.|$|\Z)','$1|$2|$3|$4')

Action #3
Actiontype 7: Import tag fields (guess values)
Source format : %TMP_TEXT%
Guessing pattern: %DD#CRC32%|%DD#MD5%|%DD_#MD5AUDIO%|%DUMMY%

Action #4
Actiontype 9: Remove fields
Fields to remove (semicolon separated): TMP_TEXT

End Action Group MyMusic Import#&5 Import DD_MD5AUDIO MD5 CRC32 from textfile (4 Actions)

DD.20150724.1124.CEST

Thank you for the sugestions