Format Reference
Supported subtitle formats, their features, and compatibility notes.
The subtitle tool supports parsing and exporting across a wide range of subtitle and caption formats.
Supported Formats
| Format | Extension | Direction | Description |
|---|---|---|---|
| SRT | .srt | Bidirectional | SubRip — the most common subtitle format. Plain text with simple HTML tags (<i>, <b>, <u>). Widely supported by media players, YouTube, and streaming platforms. |
| VTT | .vtt | Bidirectional | WebVTT — the web standard for <track> elements. Supports styling, positioning, and cue settings. Used by HTML5 video players and most web platforms. |
| SBV | .sbv | Bidirectional | SubViewer — a simple format used by YouTube's legacy subtitle system. Plain text only, no formatting tags. |
| ASS/SSA | .ass | Bidirectional | Advanced SubStation Alpha — feature-rich format with styling, positioning, effects, and karaoke timing. Common in anime fansubs and used by Aegisub. |
| SUB | .sub | Bidirectional | MicroDVD — frame-based subtitle format. Uses frame numbers instead of timestamps, making it framerate-dependent. |
| DFXP | .dfxp | Bidirectional | Distribution Format Exchange Profile — XML-based format, predecessor to TTML/IMSC. Used in some broadcast and streaming workflows. |
| SAMI | .smi | Bidirectional | Synchronized Accessible Media Interchange — HTML-based Microsoft format. Supports multiple languages in a single file. |
| IMSC | .xml | Bidirectional | Internet Media Subtitles and Captions — W3C standard based on TTML. Required by some broadcast and OTT platforms. |
| FCPXML | .fcpxml | Bidirectional | Final Cut Pro XML — used to import/export subtitle timing from Apple's Final Cut Pro. |
| SCC | .scc | Bidirectional | Scenarist Closed Captions (CEA-608) — hex-encoded caption data with SMPTE timecodes. Standard for North American broadcast closed captioning and DVD authoring. |
| EBU-STL | .stl | Bidirectional | European Broadcasting Union STL — binary format used in European broadcast workflows. Carries metadata like language, program title, and translator info. |
| Graphics STL + Images | .zip | Export only | Graphics STL manifest with rendered PNG subtitle images. Used in DVD/Blu-ray authoring pipelines. Exports as a ZIP bundle containing the .stl timing file and one .png per entry. |
| CSV | .csv | Bidirectional | Comma-separated values with columns for index, start time, end time, and text. Useful for spreadsheet editing and data processing. |
| JSON | .json | Bidirectional | Structured JSON array of subtitle entries. Handy for programmatic workflows and API integrations. |
| TXT | .txt | Bidirectional | Plain text transcript — one entry per line/block with no timing information. Useful for extracting dialogue as a text document. |
Choosing a Format
- For web delivery: VTT — it's the W3C standard and works natively with HTML5
<video>. - For maximum compatibility: SRT — supported by virtually every media player and platform.
- For styled subtitles: ASS — full control over fonts, colors, positioning, and effects.
- For broadcast delivery: IMSC or EBU-STL — required by many broadcasters and OTT platforms.
- For closed captioning: SCC — the standard CEA-608 format for North American broadcast and DVD.
- For DVD/Blu-ray authoring: Graphics STL + Images — renders subtitle text to image files with a timing manifest for disc authoring tools.
- For editing in NLEs: FCPXML for Final Cut Pro workflows.
- For data processing: CSV or JSON — easy to manipulate programmatically.