Metadata Generation

For the media in your library, Sovereign generates three kinds of derived metadata: trickplay thumbnails, media images, and subtitle tracks. Background workers inside the server produce the thumbnails, the images and the image-based subtitle tracks; text subtitles are written by the stream you’re watching.

Common Behaviour

All the metadata pipelines work the same way:

Lazy triggering - generation doesn’t start at import time. It starts the first time someone uses the content, by starting playback or requesting an asset.
Deduplication - if a job is already queued or running for a given piece of media, a second request for the same media won’t start a duplicate job.
Status tracking - each asset moves through a lifecycle (Queued → Processing → Ready, or Error if generation fails). Once an asset is Ready and its files are on disk, it isn’t generated again. One that failed is tried again the next time it’s needed.
Bounded concurrency - image downloads have their own worker limit. The two heaviest pipelines (trickplay and image-based subtitles) each run one job at a time and share one host-wide ceiling so they can’t saturate the server between them, with a slot held back so subtitles a viewer is waiting on never queue behind trickplay. See the Configuration Overview for the relevant settings.
Secure delivery - every generated asset is served through a short-lived link handed out only to a signed-in user, and a request without a valid link is refused.

Pipelines

Media images belong to the media item itself (a movie or TV series), while trickplay thumbnails and subtitles belong to a specific media file. A movie with multiple files (different quality versions, for example) shares one set of artwork but has its own trickplay and subtitle assets for each file.

Trickplay Thumbnails - seek preview sprite sheets generated per file on first playback, along with the file’s chapter markers and where its end credits begin
Media Images - posters, backdrops, and artwork shared across all files for a given media item
Subtitles - text tracks delivered inside the stream, and image-based tracks prepared per track for the client to draw

Titles, artwork, people and descriptions shown in screenshots are fictional and were created for illustration. Sovereign doesn't include or supply any media: it plays the library you bring.