How to make bulk changes to the Album field by adding a word in front of the current field text?

I have hundreds of tags that show the name of a classical composition in the Album field, like this:
"Suite for Orchestra No. 1 in D Minor, Op. 43, TH 31". They have arrived in that form because I've created a title field by converting the file name, and then used a "format value" action to copy the title field to the album field without adding the info in the title field about the movement number and tempo markings.

However, my preference would be to continue what I did in the past for thousands of files when I created tags manually: have the Album field start with the composer's last name. Thus, my preferred text for the sample provided would be: "Tchaikovsky: Suite for Orchestra No. 1 in D Minor, Op. 43, TH 31"

Because I'm trying to add something at the start of the Album name field, I can't use a "replace" action, because there's nothing prior to the first word of the existing title to replace. The first letter of Suite exists at the left margin of the Album field.

Neither do I want to iterate through each field manually and paste "Tchaikovsky: " [with one space after the colon] at the start of the current text in the album field.

Any thoughts on how I can do this in bulk to apply the chosen term to many fields? I realize I'll have to run the script many times, so that I can manually select the names of the different composers that will be used for each set of changes.

Instead of "Replace" the action-type command would be "Format Value".
To add the composer's last name would be easy if you have a tag-field filled with this information, for instance the field COMPOSER or COMPOSERSORT.

Action Type: Format Value
Field: ALBUM
Format String: %composer%: %album%

You also can use the Converter Tag->Tag which has an immediate preview and so is very convenient for testing format strings.

Convert-> Tag-Tag
Field: ALBUM
Format String: %composer%: %album%

Note: You have to care that you only use this action once because otherwise you would add the composer again and again to the album-field.

If you don't have a field with only the composer's last name I suggest that you first create one. I use the field COMPOSERSORT that way.
COMPOSER: Ludwig van Beethoven
COMPOSERSORT: Beethoven

Thanks for your thought.

Unfortunately, I have no field that contains only the composers' last name. However, in the both the composer and artist fields, I have that info, along with the first name. It's presented two ways: Aaron Copland (artist); Copland, Aaron (composer).

I found the way to add a new field, and can call it COMPOSERSORT.

Now, to use your suggestion, I need another suggestion. Using the existing info, how do I get just the last name into the new field?

You can use an action:
Action Type: Guess values
Source format: %composer%
Guessing pattern: %composersort%, %dummy%

This type of action uses an unique separator. In this case it is the comma with a space behind. The content before the separator goes to COMPOSERSORT, the erst into nirvana.

There is no need to add this field manually. The action "Guess values" creates this field.

I must be missing something, but I don't know what. Here's what I did, which I think is the long version of what you've suggested.

I create the new column and name it COMPOSERSORT. I place my cursor in that column, in a row that has "Copland, Aaron" in the Composer field. I select Action - Guess Values, and copy/paste the text you provided into the template. When I then click OK, I get the response, "Formatted tag in 1 of 1 files."

However, no text appears in the COMPOSERSORT field.

If I understand your approach correctly, at least the text of my format string should appear there, which would obviously be incorrect.

You need to proceed as follows:

  1. Load all files into Mp3tag you want to treat this way.

  2. Mark all these files in the list view. (CTRL-A)

  3. Select in the menu Actions->Actions Quick->Action type->Guess Values->o.k.

  4. Source format: %composer%
    Guessing pattern: %composersort%, %dummy%

  5. o.k.

The Quick action is used for actions you don't want to use later again. For actions you want to preserve for later use select "actions" and in that menu, create a new action group and save it. An action group can have many combined single actions or only just one.

You should always test your actions with test-files and not apply any mass changes with your originals, before you are sure that the action works as intended.

I'm sorry, but I followed your directions previously, and then went through your checklist again this time. I selected a different set of files as well. However, the script produces no new text.

Do you look at the content of your created column? Maybe the definition of the column is wrong. You should show us a screenshot of your column definition. It has to look like this:

Mark a file and have a look at the extended tag-view (ALT-t). Do you see a field COMPOSERSORT there with your content?

You found where I made my mistake. I'd never created a new field before, and when I did this one I didn't fill in all the necessary info at the top of the template. The "value" field was left empty. When I filled with %composersort%, your "guess values" action worked, even for "compound" names like "Tchaikovsky, Pyotr Ilyich."

Once I had values in the %composersort% field, and ran your action "%composersort%: %album%", the composer name filled itself into the album field at just the right place.

Thanks very much. It's quite a relief to find that I can get this done.