My search for a command line MP3 tagger (to import cover art) led me to eyed3 (
http://eyed3.nicfit.net/).
It's a standalone Python script ("eyed3.py" guess that's what you need) or a Python library.
I'm not sure if you need to install the libary to use the script, but anway. It works under WIndows, but the default installer is Windows unfriendly. So attached to this post is a customized setup. You'll still need an installation of Python.
If it's too much hassle, you can also try Metamp3 (just Google it). Excellent command line tagger for Windows, but not supporting unicode... like it removes German umlauts from ID3 tags... so I can't use it.
Command line reference of eyed3.py
How to Use eyeD3
The 'eyeD3' utility program can perform most ID3 tasks, and it is also the best example of how to use the API. It supports the following features:
Usage
=====
eyeD3 [OPTS] file [file...]
Options
=======
--version show program's version number and exit
-h, --help show this help message and exit
Tag Versions
------------
-1, --v1 Only read/write ID3 v1.x tags. By default, v1.x tags
are only read if there is not a v2.x tag.
-2, --v2 Only read/write ID3 v2.x tags.
--to-v1.1 Convert the file's tag to ID3 v1.1. (Or 1.0 if there is
no track number.)
--to-v2.3 Convert the file's tag to ID3 v2.3
--to-v2.4 Convert the file's tag to ID3 v2.4
Tag Data
--------
-a STRING, --artist=STRING
Set artist
-A STRING, --album=STRING
Set album
-t STRING, --title=STRING
Set title
-n NUM, --track=NUM
Set track number
-N NUM, --track-total=NUM
Set total number of tracks
-G GENRE, --genre=GENRE
Set genre. The argument is a valid genre string or
number. See --list-genres
-Y STRING, --year=STRING
Set a four digit year.
-c [LANGUAGE]:[DESCRIPTION]:COMMENT, --comment=[LANGUAGE]:[DESCRIPTION]:COMMENT
Set comment
-L [LANGUAGE]:[DESCRIPTION]:LYRICS, --lyrics=[LANGUAGE]:[DESCRIPTION]:LYRICS
Set lyrics
-p STRING, --publisher=STRING
Set the publisher/label text
--remove-comments Remove all comment frames.
--remove-lyrics Remove all lyrics frames.
--add-image=IMG_PATH:TYPE[:DESCRIPTION]
Add an image to the tag. The description and type
optional, but when used, both ':' delimiters must be
present. The type MUST be an string that corresponds
to one given with --list-image-types. If the IMG_PATH
value is empty the APIC frame with TYPE is removed.
--remove-images Remove all image (APIC) frames.
--add-object=OBJ_PATH[:DESCRIPTION[:MIME-TYPE[:FILENAME]]
Add an encapsulated object to the tag. The description
and filename are optional, but when used, the ':'
delimiters must be present. If the OBJ_PATH value is
empty the GEOB frame with DESCRIPTION is removed.
-i DIR, --write-images=DIR
Causes all attached images (APIC frames) to be written
to the specified directory.
-o DIR, --write-objects=DIR
Causes all attached objects (GEOB frames) to be written
to the specified directory.
--set-text-frame=FID:TEXT
Set the value of a text frame. To remove the frame,
specify an empty value. e.g., --set-text-frame="TDRC:"
--set-user-text-frame=DESC:TEXT
Set the value of a user text frame (i.e., TXXX). To
remove the frame, specify an empty value. e.g., --set-
user-text-frame="SomeDesc:"
--set-url-frame=FID:URL
Set the value of a URL frame. To remove the frame,
specify an empty value. e.g., --set-url-frame="WCOM:"
--set-user-url-frame=DESC:URL
Set the value of a user URL frame (i.e., WXXX). To
remove the frame, specify an empty value. e.g., --set-
user-url-frame="SomeDesc:"
--play-count=[+]N If this argument value begins with '+' the tag's play
count (PCNT) is incremented by N, otherwise the value
is set to exactly N.
--bpm=N Set the beats per minute value.
--unique-file-id=OWNER_ID:ID
Add a UFID frame. If the ID arg is empty the UFID
frame with OWNER_ID is removed. An OWNER_ID MUST be
specified.
--set-encoding=latin1|utf8|utf16-BE|utf16-LE
Set the encoding that is used for _all_ text frames.
This only takes affect when the tag is updated as the
result of a frame value being set with another option
(e.g., --artist=) or --force-update is present.
--remove-v1 Remove ID3 v1.x tag.
--remove-v2 Remove ID3 v2.x tag.
--remove-all Remove both ID3 v1.x and v2.x tags.
Misc. Options
-------------
--rename=NAME Rename file (the extension is not affected) based on
data in the tag using substitution variables: %A
(artist), %a (album), %t (title), %n (track number),
and %N (total number of tracks)
--fs-encoding=ENCODING
Use the specified character encoding for the filename
when renaming files
-l, --list-genres Display the table of ID3 genres and exit
--list-image-types List all possible image types
--strict Fail for tags that violate the ID3 specification.
--jep-118 Output the tag per the format described in JEP-0118.
See http://www.xmpp.org/extensions/xep-0118.html
--nfo Output NFO information.
--lametag Prints the LAME Tag.
--force-update Update the tag regardless of whether any frames are set
with new values.
--no-color Disable color output
--no-zero-padding Don't pad track or disc numbers with 0's
--no-tagging-time-frame
When saving tags do not add a TDTG (tagging time) frame
-F DELIM Specify a new delimiter for option values that contain
multiple fields (default delimiter is ':')
-v, --verbose Show all available information
--debug Trace program execution.
--run-profiler Run using python profiler.
