Overview
Commonly supported music metadata tags are generally designed and used for popular music and are not a good fit for genres that have more than one track (“song”) per performance (symphony, Broadway musical, etc.), more than one credited composer, or more than one individual in the performance.
Working in the constraints of a mixed Apple MacOS iTunes and Android environment, I have some thoughts on how available metadata tags can be used.
Genre
While there appear to be conventions, there does not appear to be any official standard on genre naming. The wide variety of music found under the fairly common genres names of “Country & Folk”, “Jazz” or even “Classical” really needs to be further divided. I am not consistent (I refuse to put a Broadway musical into the more common “soundtrack” category) but I have decided to generally make genre names hierarchical in format with a “-” separating the levels (e.g. “Country & Folk – Bluegrass”).
Album
There are two schools of thought I’ve seen searching the Internet on how to deal with albums:
- Keep the original LP or CD album name and structure intact. One advantage of this is that metadata for the album can be found on the Internet. For albums that have more than one performance (e.g. a CD with trumpet concertos by both Hummel and Haydn) use a “grouping” tag to mark the separate performances. Unfortunately, Android’s Media Service does not currently support a grouping tag nor a suitable substitute for it.
- Break the CD into “synthetic” albums, each performance becoming a separate album. This is supported by most platforms, specifically Android, and is what I decided to do. For classical music I have decided to name these performance related albums using the composer, a colon and then the performance name. (e.g. “Beethoven: Piano Concerto #3 In C Minor, Op. 37”). This aids in sorting and searching as composer is not a field one can easily search or sort on in iTunes.
Song Title
Track titles from the original CDs vary in format quite a bit. Some include the full performance name in addition to the movement or song. (e.g. “Old Friends (from Merrily We Roll Along)” or “Bach (CPE): Sinfonia #1 In G, H 657 1. Allegro Di Molto”). I have decided to remove album/performance names from the individual tracks (e.g. “Old Friends (from Merrily We Roll Along)” becomes “Old Friends” and “Bach (CPE): Sinfonia #1 In G, H 657 1. Allegro Di Molto”) becomes “1. Allegro Di Molto”).
Classical music often has a movement number preceeding the name. I have decided to retain that for display purposes even though the information is redundant with the information contained in the “track” tag.
Composer
As downloaded from the Internet or found embedded on post mid-1990’s CDs, there is a wide variety of conventions for composer information, especially if more than one individual is being credited.
For classical music, I have decided to separate individuals with a semicolon and to have each name in the form “surname, name” as in a sorted list I would rather look under “B” for Bach rather than “C” (Carl Philipp Emanuel Bach) or “J” (Johann Sebastian Bach).
For other genres, I generally follow the same convention as for classical music but am not quite as consistent. Still, you are more likely to see “Kern, Jerome David” than “Jerome Kern” in my library. Part of the inconsistency is that iTunes does not have a quick way to view or sort music by composer so I am less likely to be thorough. (edit: Found that you can add a composer field to the list display of iTunes then sort by that column to find all the composers.)
With respect to album naming, if there are multiple composers in my collection with the same surname, I try to distinguish that in the album name. (e.g. “Bach (CPE): Sinfonia #5 In B Minor, H 661”).
Artist
On the Internet, metadata for artists seems to exclusively be of the form “name surname”. I’ve decided to follow that convention even though it is at odds with my choice for the use of the composer field. I still use a semicolon to separate multiple individuals or named groups. And I generally order the artists by soloist, conductor, group (e.g. “Radu Lupu; Zubin Mehta; Israel Philharmonic Orchestra”).
Album Artist
I don’t find much use for this tag, especially as most of my collection has been broken into a single composition/performance per album. This means that the track/song artist is nearly always identical to the album artist.
Android Media Service
Here is a summary, taken from current source code, of the information that Android keeps about each music file:
| Field/Tag | Type | Interface | Description |
| _count | INTEGER | BaseColumns | The count of rows in a directory. |
| _data | TEXT | MediaColumns | Path to the file on disk |
| _display_name | TEXT | MediaColumns | The display name of the file |
| _ID | INTEGER | BaseColumns | The unique ID for a row. |
| _size | INTEGER | MediaColumns | The size of the file in bytes |
| album_artist | TEXT | AudioColumns | The artist credited for the album that contains the audio file |
| album_id | INTEGER (long) | AudioColumns | The id of the album the audio file is from, if any |
| album_key | TEXT | AudioColumns | A non human readable key calculated from the ALBUM, used for searching, sorting and grouping |
| album | TEXT | AudioColumns | The album the audio file is from, if any |
| artist_id | INTEGER (long) | AudioColumns | The id of the artist who created the audio file, if any |
| artist_key | TEXT | AudioColumns | A non human readable key calculated from the ARTIST, used for searching, sorting and grouping |
| artist | TEXT | AudioColumns | The artist who created the audio file, if any |
| bookmark | INTEGER (long) | AudioColumns | The position, in ms, playback was at when playback for this file was last stopped. |
| compilation | TEXT | AudioColumns | Whether the song is part of a compilation |
| composer | TEXT | AudioColumns | The composer of the audio file, if any |
| date_added | INTEGER | MediaColumns | The time the file was added to the media provider. Units are seconds since 1970. |
| date_modified | INTEGER | MediaColumns | The time the file was last modified. Units are seconds since 1970. |
| duration | INTEGER (long) | AudioColumns | The duration of the audio file, in ms |
| genre | TEXT | AudioColumns | The genre of the audio file, if any. Does not exist in the database – only used by the media scanner for inserts. |
| height | MediaColumns | The height of the image/video in pixels. | |
| is_alarm | INTEGER (boolean) | AudioColumns | Non-zero if the audio file may be an alarm |
| is_drm | INTEGER (boolean) | MediaColumns | Non-zero if the media file is drm-protected |
| is_music | INTEGER (boolean) | AudioColumns | Non-zero if the audio file is music |
| is_notification | INTEGER (boolean) | AudioColumns | Non-zero if the audio file may be a notification sound |
| is_podcast | INTEGER (boolean) | AudioColumns | Non-zero if the audio file is a podcast |
| is_ringtone | INTEGER (boolean) | AudioColumns | Non-zero if the audio file may be a ringtone |
| mime_type | TEXT | MediaColumns | The MIME type of the file |
| title_key | TEXT | AudioColumns | A non human readable key calculated from the TITLE, used for searching, sorting and grouping |
| title | TEXT | MediaColumns | The title of the content |
| track | INTEGER | AudioColumns | The track number of this song on the album, if any. This number encodes both the track number and the disc number. For multi-disc sets, this number will be 1xxx for tracks on the first disc, 2xxx for tracks on the second disc, etc. |
| width | MediaColumns | The width of the image/video in pixels. | |
| year | INTEGER | AudioColumns | The year the audio file was recorded, if any |