Subtitles for the deaf and hard of hearing (SDH)

SDH subtitles include dialogue and relevant speaker, music and sound information for viewers who cannot rely on the soundtrack.

SDH means subtitles for the deaf and hard of hearing. The content normally includes dialogue plus sound information needed to understand the scene without relying on the soundtrack.

A line such as “I'll be there” can be insufficient when the speaker is off screen or when an approaching sound changes the scene's meaning.

Dialogue-only wording Useful additional caption information in an invented scene
I'll be there. MAYA: I'll be there. when the speaker is otherwise unclear
No spoken line [train approaching]
No spoken line [music stops abruptly] when that change matters
Did you hear that? A description of the relevant sound prompting the question

The goal is meaningful scene information, not indiscriminately labeling every sound. A speaker label can be unnecessary when the picture makes the identity obvious; its value depends on the scene.

SDH describes content, not storage

An SDH presentation can use SRT, WebVTT, ASS, a bitmap format or a caption service. It can be external, embedded or streamed. A file extension does not determine whether the track contains sound descriptions.

Likewise, a track can be in the same language as the dialogue or provide an accessible translation. Language and accessibility role are independent dimensions of selection.

A conversion to a simpler text format should preserve speaker and sound information if that is the selected content's purpose. Discarding bracketed descriptions as “non-dialogue” changes what the viewer receives.

Layout and timing make the information usable

The captions still need to coincide with the relevant speech or sound, remain readable and fit the presentation. Several sounds or speakers can compete for limited caption space.

An app's text-size or background preference can improve legibility where the representation permits it. It cannot add a missing sound description to a dialogue-only track. A bitmap's lettering is already drawn; resizing that image is different from reflowing editable text.

For Emby, subtitle preferences provide a hearing-impaired selection mode, while external naming identifies SDH resources. The actual track contents establish whether those descriptions are present.

Audio description serves another information need

An audio-description track narrates relevant visual information for a listener who cannot rely on the picture. SDH supplies relevant audio information in visible captions for a viewer who cannot rely on the sound.

A media item can provide both. They are separate content choices rather than alternate names for the same accessibility track.

See Also

References