Rename file only if extension matches (.Mp3, .Flac, etc)

Support
2

You did not show the specific Regular Expression, you did talk about, so I assume there is no RegExp involved, but only basic Mp3tag scripting features.

If you want to apply an action to append some data to an existing tag-field content, then the following proposals may help.

  1. Set Filter
    "%_extension%" IS "FLAC"

  2. Use Action
    Action: Format value
    Field: _FILENAME
    Formatstring: %_filename%' [original]'

... or ...

  1. Use Action
    Action: Format value
    Field: _FILENAME
    Formatstring: $if($eql($lower(%_extension%),'flac'),%_filename%' [original]',%_filename%)
    Because %_extension% returns always lower cased names this should work too ...
    Formatstring: $if($eql(%_extension%,'flac'),%_filename%' [original]',%_filename%)

See also:
Actions

DD.20120531.1218.CEST