| Word | Description |
| S/PDIF | S/PDIF specifies a Data Link Layer protocol and choice of Physical Layer specifications for carrying digital audio signals between devices and stereo components over either optical or electrical cable. The name stands for Sony/Philips Digital Interconnect Format (more commonly known as Sony Philips Digital InterFace), the two companies being the primary designers of the S/PDIF format. |
| SMI | SAMI (Synchronized Accessible Media Interchange) is a Microsoft accessibility initiative released in 1998. The structured markup language is designed to simplify creating captions for media playback on a PC, i.e. not for broadcast purposes. |
| SRT | SubRip is a software program for Windows which "rips" (extracts) subtitles and their timings from video. SubRip can extract from live video, video files and DVDs, then record the extracted subtitles and timings as a text file, and can save the recognized subtitles as bitmaps for later subtraction (erasure) from the source video. |
| SSA | SubStation Alpha (or Sub Station Alpha), abbreviated SSA, is a subtitle file format created by CS Low (also known as Kotus) that allows for more advanced subtitles than the conventional SRT and similar formats. |
| SUB | MicroDVD is a subtitle file format for digital video. |