How it works


Subliminal uses multiple providers to give users a vast choice and have a better chance to find the best matching subtitles. Current supported providers are:

  • Addic7ed
  • LegendasTV
  • NapiProjekt
  • OpenSubtitles
  • Podnapisi
  • Shooter
  • TheSubDB
  • TvSubtitles

Providers all inherit the same Provider base class and thus share the same API. They are registered on the subliminal.providers entry point and are exposed through the provider_manager for easy access.

To work with multiple providers seamlessly, the ProviderPool exposes the same API but distributes it to its providers and AsyncProviderPool does it asynchronously.


Rating subtitles and comparing them is probably the most difficult part and this is where subliminal excels with its powerful scoring algorithm.

Using guessit and enzyme, subliminal extracts properties of the video and match them with the properties of the subtitles found with the providers.

Equations in subliminal.score give a score to each property (called a match). The more matches the video and the subtitle have, the higher the score computed with compute_score() gets.


Various libraries are used by subliminal and are key to its success:

  • guessit to guess information from filenames
  • enzyme to detect embedded subtitles in videos and read other video metadata
  • babelfish to work with languages
  • requests to make human readable HTTP requests
  • BeautifulSoup to parse HTML and XML
  • dogpile.cache to cache intermediate search results
  • stevedore to manage the provider entry point
  • chardet to detect subtitles’ encoding
  • pysrt to validate downloaded subtitles