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Subtitle Resolver

FFmpeg Builder: Subtitle Resolver

The Subtitle Resolver updates the FFmpeg Builder subtitle model so the output file contains the subtitle languages you require.

It can keep existing subtitle tracks, remove unwanted languages, convert image-based subtitles to text, translate an existing text subtitle track, or generate subtitles from the audio track when no text source is available.

note

This flow element requires FileFlows Forge to be configured and available.

How It Works​

  1. Reads the configured target subtitle languages.
  2. Marks subtitle tracks that do not match the target languages for removal, including forced subtitles for unrequested languages.
  3. Restores previously removed subtitle tracks that match the target languages.
  4. Uses an existing text subtitle track as a master source when one is available.
  5. Converts matching image-based subtitle tracks to SRT text when enabled.
  6. Translates the master text track into any missing target languages.
  7. Generates a new subtitle track from the audio track when no subtitle source is available.
  8. Sorts subtitle tracks to match the configured language order, with forced tracks prioritized.

Configuration​

Languages​

The subtitle languages required in the output file.

You can specify languages by their ISO 639-2/T 3-letter code or ISO 639-1 2-letter code.

For example:

  • eng or en for English
  • spa or es for Spanish
  • deu or de for German
  • fra or fr for French
  • jpn or ja for Japanese

The list is normalized, deduplicated, and processed in order.

Remove Others​

Default: true

When enabled, subtitle tracks that do not match the configured languages are marked for removal. This includes forced subtitle tracks whose language is not in the configured list.

Forced subtitle tracks are preserved only when their language matches one of the configured languages.

Convert Image Subtitles​

Default: true

When enabled, matching image-based subtitle tracks such as PGS or VobSub are converted to text-based SRT subtitles through Forge.

If conversion succeeds, the original image subtitle track is replaced in the output model with the converted text subtitle track.

Source Selection​

The resolver chooses a subtitle source in this order:

  1. Existing text subtitle track for the target language.
  2. Existing image subtitle track for the target language, if image subtitle conversion is enabled.
  3. Existing text subtitle track in another language, used as a master source for translation.
  4. Audio transcription, used to create a new master subtitle track.

When an audio transcription is used, the detected transcription language becomes the master source. If the first requested language does not match the transcription language, the resolver creates the native-language subtitle and translates it to the requested language as needed.

Outputs​

  1. Subtitle tracks were resolved and the FFmpeg Builder model was updated.
  2. No subtitle changes were needed, or no changes could be applied.