Where is song metadata stored - library or in-file?

It has been a while since I worked on my SortDateAdded script but this is a pretty comprehensive list of the properties that are available with all iTunes media files and where they are stored

The following properties are only stored in the database:

• Date Added (Can't be edited)
• (Store) Downloaded Art
• Enabled (Ticked)
• Unplayed
• Album Rating
• (Track) Rating
• Played Count
• Played Date
• Skipped Count
• Skipped Date
• Volume Adjustment
• EQ
• Start Time
• Finish Time
• Remember Bookmark Position
• Bookmark Time
• Exclude From Shuffle
• Media Kind
• Playlist Membership

The following properties are usually stored in tags, but not for file types: .mid.mov.mpeg.mpg.pdf.wav

• Embedded Art
• Track Number
• Track Count
• Disc Number
• Disc Count
• Year
• (Part of a) Compilation
• Part Of Gapless Album
• Name
• Artist
• Album Artist
• Album
• Composer
• Comment
• Genre
• Grouping

These additional properties not stored in the file for file types: .aif.mid.mov.mpeg.mpg.pdf.wav

• Video Kind
• Season Number
• Episode Number
• EpisodeID
• Show
• Description
• Sort Name
• Sort Artist
• Sort Album Artist
• Sort Album
• Sort Composer
• Sort Show

Date Modified is a property of the file rather than its tag.

I assume Duration is a fixed property stored in the header for audio & video files, even when they don't have a tag.

I haven't tested it yet (I wrote the script before I had access to iBooks) but I would assume that most, if not all, of the tag properties are also internalised for Books (.epub).

In general iTunes won't notice if a file is modified by another instance of iTunes or a third party tagging tool unless it has reason to access the tag, e.g. during playback, in which case it will update itself with the current details stored in the tags.

Note also that file types than can have an embedded tag to store metadata don't have to have one. Some can also have more than one which, together with inconsistencies in the way iTunes manages multiple tags, can mean that an update with one library might not be reflected in another.

If you are using a single media folder to support multiple libraries then probably the most useful tip is to disable the Keep iTunes Media folder organised option in each library, otherwise an edit in one library can make tracks go missing for another.

tt2

Hi Ryan, the details above were extracted from a script called SortDateAdded that I originally wrote for this thread two years ago. I will have tested the behavior of the current build of iTunes for Windows at that time. I don't actually recall the result of every test I performed in detail. Given they are principally values associated with video files so not really relevant for mp3 files, it is just possible that I missed something. Looking at my library now I can find test audio files in AAC, AIFF, ALAC & MP3 formats. The only one with data currently in the Show field is the AAC file, so perhaps I incorrectly assumed that mp3 files would behave in a similar fashion.

Retesting now I can confirm your finding that neither Show, Sort Show, Season No., Episode No., or Episode ID are preserved in an mp3 file removed from iTunes and then reimported. I will update my script accordingly.

For what it is worth the earlier post also leaves out other details such as which properties cannot be set for pdf, iTunes LP and iTunes Extras.

tt2

Section 2i,

I haven't seen a list like that, but here are the tricky parts that can be confusing to people:

The song-related metadata such as Title, Artist and Album are stored in the file itself, except for WAV files, in which case iTunes Stores it in the library.

Artwork is stored in the file if it was added via Get Info, but in the library if it was added via "Get Album Artwork."

Rating is stored in the library. Other players, such as Windows Media Player, store rating in the file, but even if it is there iTunes will not see it.

Show, Sort Show, Season Number, Episode ID, and Episode Number do not appear to be stored in the file for mp3s (using v2.4 tags). If I add values, remove the file from the library, then re-add the file, those values are lost.

(Sorry, this is on Mac. I don't know about Windows.)

Ryan Torchia wrote:

Show, Sort Show, Season Number, Episode ID, and Episode Number do not appear to be stored in the file for mp3s (using v2.4 tags). If I add values, remove the file from the library, then re-add the file, those values are lost.

Ryan,

That is not surprising, since those are tags normally used for shows, not for songs. I'd guess the v2.x standards for MP3s don't even support them, but if you want to check it out, the list is in this Wikipedia article.

I mentioned that mainly in response to the post immediately above, which listed them as being written to mp3s (albeit indirectly, by saying they were excluded from other formats).

Interestingly enough, the Description tag, which is included under the Video tab, is written to mp3s (in the subtitle/description tag). The other tags could be written to the TXXX or COMM tags if needed. Sort Composer is also written to mp3 tags, but there's no official frame in the spec for it.