Language tags for metadata
A language tag identifies a linguistic presentation with applicable language, script, region and extension information, while selection and fallback remain separate policies.
A metadata language choice can affect which title or overview a viewer receives. A language tag describes that presentation; it does not identify a different film or translate its audio.
Subtags carry different information
| Example | Interpretation |
|---|---|
| en | English |
| en-US | English with a United States region context |
| zh-Hant | Chinese in traditional script |
| zh-Hant-TW | Chinese, traditional script, Taiwan region context |
Language, script and region are related but distinct. The region does not universally tell a reader which script or spoken dialect every resource contains.
BCP 47 defines the tag structure. A conventional casing such as en-US helps readability, while the defined comparison rules are not a case-sensitive identity of movie records.
A field's language needs its own scope
The language of an overview, the original language of a work, and a local audio track's language can differ. Copying one into another changes what the field claims.
A translated title does not prove that the chosen video has that language track. An artwork-language value may instead describe text visible in a poster.
In Emby, distinguish the library's descriptive-language context from subtitle preferences and the app's interface language.
Provider conventions need interpretation
A provider may accept a language-region request, a narrower language code or a special neutral marker. Those contracts should not be rewritten as if every string were a valid BCP 47 tag.
For example, a legacy artwork marker can identify textless content using a provider-specific value. Unknown language and deliberately textless artwork also need not mean the same thing.
Keep the source convention with its mapped meaning.
Matching and fallback are chosen operations
RFC 4647 defines language matching approaches. A concrete application still decides its available set, desired range and fallback behavior.
An original library policy could try a requested fr-CA title, then available fr, then a designated original title. That is a useful example, not a required fallback chain for every provider or Emby installation.
A script-sensitive request should preserve its purpose. Falling from a traditional-script request to any Chinese string can choose a presentation the viewer did not intend.
Localized titles shows how those alternatives retain one underlying entity while supplying different labels.