Every Subtitle File Format Explained: SRT, VTT, ASS, SSA, TTML and More
There are over a dozen subtitle formats in active use. Here's what each one does, where it's used, and which one you should use for your project.
The subtitle format landscape is surprisingly complex — there are over a dozen formats in active use, each with different capabilities and platform support. Here's a complete guide to the most important ones.
The Major Formats
SRT (SubRip): plain text, universal compatibility, basic timing only. Use for: YouTube, most platforms, video players. WebVTT: HTML5 standard, supports positioning and styling. Use for: web video players, HTML5 <video> tag. ASS/SSA (Advanced SubStation Alpha): supports advanced styling, positioning, karaoke timing, and complex animations. Use for: anime fansubs, gaming videos, highly stylised subtitle needs. TTML/DFXP: XML-based, used for broadcast and streaming (Netflix, BBC iPlayer). Required for professional broadcast delivery. SBV: YouTube's native subtitle format (similar to SRT but different timecode format). STL: EBU broadcast format, used in European television production.
Choosing the Right Format
For social media and web platforms: SRT is almost always the right choice. It's supported everywhere and simple to create. For HTML5 web video: WebVTT is the technical standard but SRT usually works too. For anime/gaming/styled content: ASS gives you the styling control you need. For broadcast delivery: check the platform's delivery specification — they'll specify TTML/DFXP or STL. For Netflix: they require DFXP/TTML with specific timing requirements. When in doubt: export SRT and convert to whatever else is needed. SRT→VTT and SRT→TTML conversions are trivial with free tools.
Zingo's Format Support
Zingo exports subtitles in SRT and WebVTT for all translation jobs. For broadcast and streaming platform delivery, Zingo can generate TTML on request. The workflow: generate translation in SRT, export in the format required by your target platform. If you're delivering to multiple platforms simultaneously, export multiple formats from the same translation job — you only pay for the translation once.