SubViewer

SubViewer is a subtitle file format used to store timed text that accompanies video. It originated in the late 1990s and became popular in the early 2000s, receiving support from several media players and devices of that era, including early Windows Media Player releases.

There are two main variants of SubViewer: 1.0 and 2.0. SubViewer 2.0 expanded the feature set to accommodate broader language support and formatting options, while 1.0 covered the core functionality. Over time, many users migrated to newer formats, such as SubRip (SRT) or Advanced SubStation Alpha (ASS), but SubViewer remained in use for older videos and archives.

Files commonly carry the .sub extension, though some variants and editors used different names. A SubViewer subtitle consists of blocks that begin with a time stamp and are followed by one or more lines of subtitle text. The time stamp indicates when the text should appear; the display duration is generally determined by the timing of subsequent blocks rather than a separately declared end time. The format supports multi-line subtitles within a single block.

Formatting in SubViewer is relatively limited. Some implementations allow basic inline formatting through simple tags (for emphasis or color), but the emphasis is modest compared to newer formats that offer richer styling.

Today SubViewer is largely obsolete in mainstream use, having been superseded by formats with more robust timing and styling capabilities. It may still be encountered in older video libraries, and conversion tools exist to translate SubViewer files into modern subtitle formats for contemporary players and platforms. See also: SubRip, SubStation Alpha.