Adding leaving zeroes for entire tree?

Use case: I have my collection of downloaded mp3s via vinyl codes. They are on SD card and I play in my car. I play albums not playlists. So some albums are ordered 1, 11,12, 2, 3... It's very frustrating.

I read on the forum it can be done for a file by: select all the files. Open Convert>Tag-Tag Select field TRACK Enter as Format String: $num(%track%,2) Click OK to apply the converter.

Before I download the software I wish to check if it can be done for an entire directory tree?

This works for all loaded and selected files in 1 go.
To load more than 1 folder, select the folder above the album folder and/or drag&drop all folders that you want to treat from the Windows explorer into MP3tag.
Then select the files in MP3tag and start the converter

Which tag fields have you filled?
It is fairly astounding that your player cannot sort numbers correctly as these are generally numeric values and not alphabetic ones.
Or are we talking about the file name?

It's Skoda infotainment system, 2021 update. I have not downloaded the software yet just doing research first. Yes it's the file name, what are the other options?

File names are not tags.
Tags are metadata that is embedded in the files.
The function you found with

only works on the metadata.
The best way would be to fill the tags first, see e.g. here:

Ok, thanks, I guess the clue is in the name of your software. Can anyone recommend other software to solve this problem?

Why don't you go the way to fill the tags first and then construct new file names from there?
I bet that your player is much better in sorting files by tag data than by file name.

If you only want to add a leading zero to the file name without any interpretation whether that makes sense or not (as that is the consequence if you use an amorphous string like a file name instead of structured data from the tags):

Use Convert>Tag-Filename
Format string: 0%_filename%

The mp3 format might have been one of the first steps in the development path. But mp3tag supports metadata tagging in virtually every audio format out there, along with many video formats as well.

From this opening request, you are already referencing a function to leverage the power of the separate tag fields. These are very helpful to have as most player apps now depend on the tags for proper sorting and browsing of a collection. The file and folder names become less relevant other than for simple identification.

If your current filenames follow the format you described with leading numbers, and do not have any metadata, the player will always resort to using whatever is there to work with. So with no tags the filename becomes the only helper.

If you could share a screenshot of your files loaded into mp3tag, it would help to identify if any metadata has been added in the past. Plus the filename format will then be visible to confirm what next step can be used to rename them.

This is the right software for what you are striving for. And the download is free (for Windows) so give it a shot.

Ok, thanks for your patience. Before downloading and giving the software a spin a final double-check:

I checked on the skoda forum and this functionality regarding tags does not seem to be on people's radar so I need to rename the files and forget about tags in this case. I could do a search by hand but I would prefer to give it the SD card drive and have the software loop through the directories and do the renaming where applicable. So it sounds like I can pick G:\ and then:
Use Convert>Tag-Filename
Format string: 0%_filename%
and it will do it?

Couldn't you test just 1 folder with the tagged approach and see what your player makes of it?
I doubt that they implemented a player that ignores tags completely. I assume that the player uses the filename as last resort but in reality likes to use the tag data.
TO speed things up:
Please show us a screenshot of 1 folder where the screenshot shows the filenames and the folder name.
I would then make a suggestion how you could harvest the data from the file name to be added as tags.

This will simply replace all filenames with the same thing preceded by a 0. But unless you use some complex filter, or select them all by hand, you will also be doing this for the tracks with double digits. And the results will still end up being the same.

Ideally if this info is extracted into the correct tag fields, you could then replace the filename completely with something like;
Format string: $num(%track%,2) %title%

The $num function makes sure the enclosed string is always at least as many digits as indicated by the number in the second term.

These would then have filenames starting with 01, 11, 12, 02, 03 plus the Title.

If your files do not already have any tag fields populated, there are simple ways to do that from potential existing information in the file and folder names. There are other threads here describing the steps for this. A screenshot with an example of your current folder and file structure would help. As would a shot of the Extended Tag window from mp3tag for any track, once you have it installed, would benefit the discussion as well.

Thanks for the replies. I am confused how screenshots of the folder structure will help, but here you go, an example album showing the entire SD card contents of that folder and what the player shows for that album:

To get data into TITLE and TRACK use Convert>Filename-TAG
Format string: %track% %title%

For the folder "Ora Belli - Ore" you could use the converter also but fill ARTIST and ALBUM this time:
Format string: %artist% - %album%\%dummy%
or if the files have the same naming pattern as in Bicep:
Format string: %artist% - %album%\%track% %title%

The converter has a preview that should show immediately how successful a data import would be.

For the folders from Bicep it would look a little different (I guess):
Format string: %artist%\%album%\%track% %title%

You can see in the reply from @ohrenkino that the folders you have help to fill the Artist and Album fields, while the filenames have Track and Title info. Getting these pieces of data from your current files helps to fill the metadata for better organizing options.

The car player image appears to show only folder browsing at the top. Is there any menu at the top level to choose things like browsing through Artist, Genre, or other categories?

Fill the info into the metadata, then use the formatting I suggested earlier to get the filename to have track numbers that include leading zeros for single digit tracks.

Just to get back to your original request and fiddle with the filename only:
Use Convert>Tag-Filename
Format string: $If($less($num(%_filename%,1),10),0%_filename%,%_filename%)
THis should work for all files starting with a number and add the leading zero only where this number is less than 10.
It does not take treat filenames with leading zero in a special way but also adds that leading zero.

Occasional visitor here.
Looking through this thread I am impressed at the quality of the dialog - the support person providing clear instructions, answers questions, is patient.

One might hope those characteristics are commonplace - but sadly there are a number of places where people seem to get little response beyond that there is something incorrectly formatted in their support request.

So kudos!

I just did that to satisfy your curiosity. For the shown album I saved the tags and all the file's date stamps changed - which I think is a dreadful solution, the file creation date should not be messed with IMHO. Anyway, I brought the SD card back to the car and the album shows in the same order, the tagging made no difference.

Going back to my original post I have such a straightforward request. Would going through the directories individually and manually renaming be faster?

I think that I already posted a suggestion to the

In respect to your observation that nothing changed - I cannot look over your shoulder and tell you which functions you have to use to properly handle that player.
Still, if you have problems with filenames, then these could be modified MUCH easier from structured tag data than fiddling with the unstructured, amorphous string of the filename.

The modified date may have changed, but not the creation date. Even if you are simply changing these in Explorer the modified date will change.

Thanks for your continued patience. This worked to rename the test album perfectly. Brilliant.

I was disappointed that the last 3 files 10-12 which did not need to be modified, were also given the same modified time. Is there any way to stop that?

When I do it for all my mp3 I do not want everyone to be modified unnecessarily,