Overview: Subtitle overlay filters

Subtitle overlay filters render or composite timed content onto video pictures through supported software or device interfaces.

Burn-in describes the visible result; a filter describes an operation used to produce it. Software, GPU and legacy filter topics explain different execution routes for that operation. Their picture formats and interfaces matter when connecting an overlay to the rest of an Emby conversion pipeline.

• Subtitle burn-in
  Subtitle burn-in composites caption pixels into decoded video pictures before encoding an output whose subtitles are no longer separately removable.

• Subtitle overlay filtering
  Subtitle overlay filtering synchronizes a current subtitle layer with video and blends its colour/coverage into the applicable picture geometry.

• Software subtitle overlay
  Software subtitle overlay renders/decodes and blends subtitle content into CPU-accessible video frames, with any hardware transfers determined by the surrounding route.

• GPU subtitle overlay
  GPU subtitle overlay uses supported interfaces to render or composite subtitle content with device-resident pictures.

• Legacy subtitle overlay filters
  Legacy ass and subtitles video filters obtain a script through their own resource path and render it into CPU video frames; native subtitle-stream filters expose a different graph boundary.