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52 terms covering subtitle formats, timing, encoding, translation, and accessibility. Use this reference to understand key concepts and find the right tools.
International standards for web accessibility including subtitle requirements. WCAG 2.1 requires captions for all prerecorded video content and recommends specific contrast ratios, reading speeds, and positioning guidelines.
Subtitles that include non-dialogue information like sound effects, music cues, and speaker identification in addition to spoken dialogue. SDH elements are often removed for general audience subtitles.
Names or identifiers placed before dialogue text to indicate who is speaking. Formats include uppercase with colon (MAN:), bracketed labels ([John]), and arrow prefixes (- John:).
A text version of podcast audio content. Well-formatted transcripts boost SEO by 7x, improve accessibility for hearing-impaired listeners, and allow audiences to search and reference specific content.
A complete text version of video or audio content. Unlike subtitles, transcripts are not time-synced and contain all spoken words plus speaker labels. Transcripts are essential for SEO, accessibility, and content repurposing.
Information embedded in subtitle files including language, author, creation date, and format version. Some formats like VTT support metadata cues. Extracting metadata helps organize large subtitle libraries.
A pattern-matching syntax used for advanced search and replace operations on subtitle text. Regex enables powerful batch operations like removing all bracketed text, finding specific patterns, or reformatting captions.
A tool that checks subtitle files for formatting errors including incorrect timestamps, missing headers, encoding issues, overlapping entries, and structural problems. Validation ensures subtitles play correctly on target platforms.
The point where a subtitle line splits into two. Optimal line breaks occur at natural linguistic boundaries (phrases, clauses) and keep related words together. Poor line breaks reduce readability by up to 30%.
Combining two or more subtitle files into a single file. Useful for joining segmented video files, combining multiple language tracks, or appending additional captions to an existing subtitle file.
Dividing long subtitle lines into shorter, more readable segments. Split tools find optimal break points at natural linguistic boundaries. Also refers to splitting one subtitle file into multiple files.
A tool that combines multiple subtitle files into a single file. Supports merging by appending, interleaving, or synchronizing multiple subtitle tracks. Used for combining episode subtitles or adding multiple language tracks.
A real-time visualization of how subtitles will appear on video. Preview tools show font, size, color, position, and timing. Essential for verifying subtitle appearance before export.
Synchronized visual effects that highlight lyrics syllable by syllable in time with music. ASS format natively supports karaoke timing with color changes, fills, and animations for professional music video subtitles.
Visual enhancements applied to subtitles including colors, shadows, outlines, backgrounds, glow effects, and animations. Effects are format-specific — ASS supports the widest range, while SRT has none.
A Unicode character (U+FEFF) placed at the beginning of text files to indicate byte order. In subtitle files, BOM can cause parsing errors in some media players. UTF-8 without BOM is the recommended encoding for all subtitle formats.
The system that maps characters to byte values in a subtitle file. UTF-8 is the universal standard supporting all languages. Incorrect encoding causes garbled text, question marks, or empty boxes in subtitles.
The universal character encoding standard for subtitle files. Supports all writing systems with backward compatibility to ASCII. UTF-8 without BOM is the recommended encoding for maximum compatibility across platforms.
A powerful subtitle format that supports full styling, positioning, animation, karaoke effects, and professional typesetting. ASS is the standard for high-quality fan subtitling and professional video production requiring pixel-perfect caption control.
A single subtitle entry in WebVTT format consisting of timing information, optional cue settings (position, alignment, size), and caption text. Cues are the building blocks of VTT subtitle tracks.
An XML-based subtitle format used primarily by Flash media players. Largely obsolete in favor of WebVTT and TTML for modern web video delivery.
A structured data format for subtitles using JavaScript Object Notation. Stores entries with index, start time, end time, and text fields. Ideal for developers building subtitle processing into applications and APIs.
A subtitle format used by YouTube's older caption system. Similar structure to SRT but uses different timestamp formatting. YouTube now prefers VTT format for new uploads.
The most widely supported subtitle format in the world. Uses simple numbered entries with comma-separated timestamps (HH:MM:SS,mmm) and plain text captions. Universal compatibility across all media players, editing software, and streaming platforms.
The predecessor to ASS format. Supports basic styling and positioning but lacks advanced features like animation and karaoke. SSA files use the .ssa extension and can be converted to ASS or SRT.
A legacy subtitle format using frame numbers instead of timestamps for timing. Frame-based timing makes SUB files dependent on video frame rate — a SUB for 25fps won't sync on 23.976fps video.
The initial lines of a subtitle file that define format type and metadata. VTT requires a WEBVTT header. ASS files have complex header sections for script info, styles, and event format definitions.
An XML-based W3C standard for timed text used in broadcast television and streaming. TTML supports rich styling and is the basis for SMPTE-TT and EBU-TT standards. Common in professional broadcast workflows.
The W3C standard subtitle format for HTML5 video. Supports CSS styling, cue positioning, chapter markers, and metadata. Required format for YouTube and Vimeo. Uses dot-separated timestamps and the WEBVTT header.
Technology that extracts text from images or video frames. OCR-generated subtitles often contain errors that need cleanup. OCR cleanup tools fix common misrecognitions in automated subtitle text.
Short, center-positioned captions optimized for TikTok's vertical video format. TikTok captions typically use large fonts, high contrast, and limited characters per line for mobile viewing.
Subtitles uploaded to YouTube through YouTube Studio. YouTube supports SRT, VTT, SBV, and ASS formats. Auto-sync feature matches uploaded transcripts to video audio. Proper captions improve search ranking by up to 15%.
A measurement of subtitle reading speed calculated by dividing the character count by the display duration. The industry standard is 20 CPS for general audiences, with lower rates for children (15 CPS) and language learners (12 CPS).
The time offset applied to shift all subtitle timestamps forward or backward by a fixed amount. Positive delay moves subtitles later; negative delay moves them earlier. Used to fix consistent sync issues.
A synchronization problem where subtitles gradually fall out of sync with audio over time. Usually caused by frame rate mismatches (e.g., 23.976fps content played at 25fps).
The total time a subtitle entry remains visible on screen, calculated as end time minus start time. Minimum 1 second, maximum 8 seconds, with optimal 3-5 seconds for standard two-line captions.
The process of correcting overlapping subtitle entries where two or more captions appear on screen simultaneously. Automatic tools shift, merge, or split entries to eliminate overlaps while preserving timing.
The frame rate of a video file. Subtitle timing is affected by frame rate differences — a SUB file created for 25fps video will not sync correctly on 23.976fps video. FPS converters adjust subtitle timing between frame rates.
The empty time between consecutive subtitle entries. Industry standard recommends 40-100ms gaps to prevent captions from blending together. Fixing gaps improves readability and viewing comfort.
A fixed time value added to or subtracted from all subtitle timestamps to correct consistent sync issues. Offset is measured in milliseconds and can be positive (move later) or negative (move earlier).
A timing error where two or more subtitle entries have overlapping time ranges, causing them to appear on screen simultaneously. Overlaps make captions unreadable and are a common export error from editing software.
The rate at which viewers can comfortably read captions, measured in characters per second (CPS). Standard is 20 CPS for adults, with adjustments for children, language learners, and complex content.
Advanced subtitle timing adjustment that stretches or compresses the entire timeline. Unlike uniform delay, retiming handles progressive desync by applying a scaling factor to all timestamps.
The alignment of subtitle timing with video audio. Perfect sync means captions appear exactly when the corresponding dialogue is spoken. Sync problems include consistent offset, progressive drift, and variable desync.
A standardized time reference format for video production. Common formats include SMPTE timecode (HH:MM:SS:FF using frames) and subtitle timecode (HH:MM:SS,mmm using milliseconds). Timecode accuracy is critical for professional subtitle work.
A time value indicating when a subtitle should appear (start time) and disappear (end time). Formats differ: SRT uses HH:MM:SS,mmm with commas, VTT uses HH:MM:SS.mmm with dots, SUB uses frame numbers.
Subtitles displaying two languages simultaneously — typically the original audio language on top and a translation below. Bilingual subtitles are popular for language learning and international film festivals.
The process of adapting subtitles for a specific language and culture, going beyond simple translation. Includes adjusting idioms, humor, cultural references, and reading speed for the target audience.
A database of previously translated subtitle segments that helps maintain consistency across projects. Translation memories store source-target pairs for reuse, reducing time and ensuring terminology consistency.
Navigation points embedded in subtitle files that allow viewers to jump between sections. WebVTT format supports chapter markers as special metadata cues. Useful for tutorials, courses, and long-form video content.
The native HTML5 `<track>` element used to load WebVTT subtitle files in web browsers. Supports multiple language tracks, chapter navigation, and CSS styling for accessible video playback.
The ability to apply the same subtitle operation (conversion, timing adjustment, cleanup) to multiple files simultaneously. Batch processing saves hours of repetitive work when handling TV series, course libraries, or multilingual subtitle sets.