Difference between revisions of "Library Fields"

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(Field Characteristics)
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# May be hidden from normal view/usage (these field names are shown in italics in the ''Predefined Fields'' table below)
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=== Field Data Types ===
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| align="center" | Unknown    || An unspecific catch-all type, not specifically defined.
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| align="center" | Calculated,<br />Not editable || A calculated, non-editable field whose value is automatically set.
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Revision as of 13:55, 17 January 2016

Media Center helps you manage, organize and view your files by maintaining a collection of metadata fields, or properties, about those files on a per-file basis in the Library. These properties are called Library Fields (or often just Fields).

Library Fields are managed in the Library Fields Manager available via:

Tools > Options > Library & Folders > Manage Library Fields

Some examples of Library Fields are:

  • [Artist], [Album] and [Genre] for audio files
  • [Actor], [Director], and [Aspect Ratio] for movies
  • [Series], [Season], and [Episode] for TV show episodes
  • [Width], [Height], [Caption], and [Focal Length] for images.
  • [Media Type], [Media Sub Type], [File Type], and [Name] for all file types.

When used in expressions or searches, a field is usually written by surrounding its name with square brackets, as shown above. So, Album Artist is written and used as [Album Artist], and that convention is used here on the Wiki and generally on Interact.

Fields are the main system that Media Center uses to manage, search, sort, and organize files. It is how Media Center shows Audio files under the Audio part of the Tree, and Video files under the video part of the Tree, and are the fundamental underlying structure that makes features like Media Views, Smartlists, Play Doctor, and Automatic Metadata Lookup work.

Fields, Properties, and Tags

The terms properties, fields, and tags are sometimes used synonymously in common language. Generally, we use the terms in the following manner:

  • Fields: each of the database "columns" MC uses to store metadata for each file (the idea of [Artist], [Genre], or [Series])
  • Properties: the characteristic stored for an actual file (ABBA, Disco, or The Big Bang Theory).
  • Tags: the pieces of metadata that are embedded within the files themselves, where possible (the stuff written to the files for interchange with other applications).

It might help to think of a spreadsheet, where column headers are fields, rows are files, and a row of individual cell values are the file's properties. If each row were saved to an external file, the row's cells would be called tags.

Initially, a file's Fields are filled with default values when the file is Imported or created by Media Center (e.g. when ripping a CD or DVD). Typically, this data comes from a file's internal tags, information you enter when ripping a disc, or is looked up from external databases (YADB and the Automatic Metadata Lookup system for videos). In addition, several Library Tools are available to assist in creating or modifying properties and tags.

For many file types, Media Center can also save the Library Fields into the tags within the file on disk. These tags are then available for use by other programs that support the specific file types, and can serve as a backup in case your Media Center Library is damaged or lost. The tags supported by a given file type are file type-specific, but there is often commonality or overlap in various media or file formats. Media Center helps manage this by automatically mapping its own Fields to essentially similar tags with different names in the various standard tagging formats.

For more information on tag/metadata specifications for file formats, refer to the following external websites:

In addition, Media Center allows creation of an almost limitless number of custom (or user) Fields. This allows for managing information about files that is not predefined by Media Center or by a given format's standard tags. These custom properties may also be saved to a file's tags, should the format support user-defined or extensible tags.

Saving file properties to the physical file allows tags to be re-imported by Media Center, and used by other programs on a variety of systems. While typical metadata consumes a trivial amount of extra disk storage (relative to the file's size), larger metadata such as cover art, lyrics or extensive notes may be more noticeable, especially when files are exported to smaller devices such as handhelds. See Save File Properties in Disk Files for more information.

Field Characteristics

Fields in Media Center have several defined characteristics. These are shown in the annotated example Manage Library Fields dialog.

Library Fields.png

Each field:

  1. Has a standard, unchangeable Name.
  2. Has a Display name and its pluralized version used in throughout the user interface (pluralized version not currently shown in the Media Center Predefined Fields table below)
  3. Has Flags indicating the field's applicability to the indicated media / file types: Audio, Image, Video, Data, TV
  4. Is either User data, or is automatically Calculated data via Expression
  5. Stores a particular Data Type (see Field Data Types)
  6. May be a Relational field, and if so, its related field
  7. Has rules about its Edit Type or editability (see Field Edit Types)
  8. May have a semicolon-separated list of Acceptable Values (Note: no spaces after the semicolons)
  9. May be Save in file tags (when possible). Note: was labeled "Stored ..." prior to 16.0.154.
  10. May have one or more Search keywords used in queries as abbreviated or alternate names
  11. May be a Default search field when performing search queries (see Note: Default Search Field)
  12. May be hidden from normal view/usage (these field names are shown in italics in the Predefined Fields table below)

Field Data Types

Field Data Types
Data Type Description
String An unformatted sequence of characters.
Integer A whole number (no decimal portion).
Decimal A floating point number.
Percentage A decimal from 0 to 1 indicating 0% to 100%.
List A semicolon-separated list of strings.
Date A complex type that is either date-only, or date and time. (TBD: need refs)
Unknown An unspecific catch-all type, not specifically defined.
Field Edit Types
Edit Type Description
Standard A free-format, editable field.
Clear-only A clear-only field, whose value is set or updated by Media Center.
Large Value A free-format, editable field, used for large data (e.g. lyrics, notes, descriptions). (TBD: recommended for data larger than XXX characters).
Cannot be edited A non-editable field.
Filename A file-path specification field.
Five stars A selectable, 5-star graphical field, typically used for ratings.
DVD video info TBD (currently used only for hidden field DVD Video Info).
List List fields will use standard edit or list edit (i.e. check box) style.
Calculated, Editable A calculated, editable field, whose initial value is automatically set.
Not editable
A calculated, non-editable field whose value is automatically set.

Predefined and Custom Fields

Media Center includes a number of predefined Fields, and you can define as many of your own custom Fields as you'd like. To view and manage the Fields currently available in your Library, use the Field Manager available at Tools > Options > Library & Folders > Manage Library Fields.

More information about the predefined fields can be found in the Predefined Library Fields article.

Custom fields may be added with the Add New Field Manage Library Fields dialog. Custom fields can act as library-wide global values, to be used in expressions, as columns, etc.

Custom fields may be calculated expression fields, in that they will be evaluated when used. Storage for calculated fields does not add additional library storage per file, since they are evaluated when used. If configured to be default search fields, calculated fields will produce some search performance penalty in search box suggestions, and possibly other library searches.

Values of calculated fields cannot be stored in file tags.

Tag Import Options

Media Center provides a few options for the importation of tags for some file types. These encoder-specific options are available under Tools > Options > Encoding > Encoder > Encoder settings... (pre-MC18, see Plug-in Manager > Input).

For images and video, Media Center will fill in the Album field with the year of the image or video (if the album field is otherwise empty). This puts a reasonable value there when importing directly from a digital camera. (TBD - should this be moved? Is it comprehensive wrt other types/fields?)

To import non-default file tags into Media Center, first create a custom field named exactly as the physical tag appears in the media file. Subsequent imports, or Update library (from tags) will populate the custom field with the file tag values. A tag dump will show the physical file tags for a single selected file.

Classical Music

The tagging of classical music is unfortunately more complex and standards are lax. See Tagging Classical Music.


For more comprehensive information on tagging photos, see Photo Tagging.