Subtitling

Subtitling is the practice of displaying text on screen to convey spoken dialogue in video content. Subtitles are typically translations for audiences who do not understand the original language, but they can also render non-speech information. Subtitles differ from captions, which are designed primarily to aid accessibility by describing sound effects, music, and speaker identity for the deaf and hard-of-hearing.

Subtitles can be open or closed. They may be interlingual translations or intralingual renderings (transcription or transliteration). Some tracks also include non-speech information such as speaker labels and sound cues used for accessibility in specific contexts.

Creating subtitles typically involves script extraction or transcription, translation, and timing to match speech. Typesetting ensures legible lines with appropriate length and reading speed, while QC checks synchronization, accuracy, and formatting. File formats such as SRT, WebVTT, and TTML are used for distribution, with encoding that supports multiple languages and accessibility features.

Industry guidelines address legibility (character per line, line count, and display duration), punctuation conventions, and safe on-screen placement. Accessibility standards, such as SDH (for captions) and cues for sound effects, are often required by broadcasters or platforms. Files may include metadata for language, audience, and platform constraints.

Subtitling emerged with sound film and became common in television and cinema during the mid-20th century, expanding with globalization and streaming. Current trends include live subtitling using speech recognition, human post-editing, and AI-assisted localization, as well as multiple track formats for cross-platform distribution.