# WebVTT · TTML · SBV · SRT Subtitle Converter Convert subtitles between WebVTT, TTML (with SMPTE frame timing and styles), YouTube SBV and SRT — frame-precision time axes (23.976/24/25/29.97 drop-frame/30/50/59.94 DF/60), TTML tts styles bridged to WebVTT ::cue CSS, cue-id uniqueness, and IMSC 1.0.1 compatibility checks. > Canonical page: https://elysiatools.com/en/tools/webvtt-ttml-sbv-subtitle-time-axis-and-cue-style-converter - **Category:** Media - **Keywords:** subtitle converter, ttml to srt, webvtt converter, srt to vtt, youtube sbv, ttml to webvtt, drop frame timecode, imsc 1.0.1, smpte timecode subtitles, caption converter ## Overview One cue model behind four formats: WebVTT (STYLE/REGION blocks, cue settings, unique identifiers), TTML (ttp:frameRate + frameRateMultiplier 1000:1001 + dropMode dropNTSC/dropPAL time expressions, styling inheritance through references, inline span styling), YouTube SBV and SRT. Every timestamp is normalized to milliseconds first, then re-rendered exactly in the target syntax — SRT comma milliseconds, WebVTT dotted timestamps, SBV hour-compressed form, TTML clock time or SMPTE HH:MM:SS:FF codes. The SMPTE path implements real drop-frame math: frames are dropped at the start of each minute except every tenth (2 frames at 29.97, 4 at 59.94), matching broadcast timecode to within one frame over 24 hours. Pick a frame rate and cue boundaries snap onto the frame grid with a report of how many cues moved and by how much, so a 23.976 master can round-trip to TTML SMPTE times and back without drift. TTML tts:fontFamily/textAlign/backgroundColor/color/… map to WebVTT ::cue(.class) CSS with cue text wrapped in , and textAlign also becomes an align: cue setting; in the other direction WebVTT classes come back as TTML style references. IMSC checks cover a practical subset of the 1.0.1 profile: profile declaration, ittp:aspectRatio, frame-based times requiring ttp:frameRate, the permitted styling attribute set, and per-cue time sanity. ## Inputs - **Subtitle source** (textarea): Paste SRT / WebVTT / TTML / SBV content here… - **Source file (optional)** (file) - **Source format** (select) - **Target format** (select) - **Frame rate** (select) - **SMPTE frame times (TTML target)** (checkbox) - **IMSC 1.0.1 checks** (checkbox) - **Output language (TTML)** (text): en ## When to use - Converting broadcast TTML packages with SMPTE timecodes into web-ready WebVTT caption tracks. - Exporting standard SRT or YouTube SBV transcripts to styled, frame-accurate TTML files for broadcast delivery. - Eliminating timecode drift across 23.976, 24, 25, 29.97 DF, or 59.94 DF video masters by snapping cue boundaries onto exact frame grids. ## How it works - Paste subtitle text directly into the editor or upload an SRT, WebVTT, TTML, or SBV file. - Select your target format, frame rate, and optional parameters like SMPTE timecode generation, output language, and IMSC 1.0.1 validation. - Review and copy the converted subtitle output with normalized timestamps, mapped cue styles, and frame alignment reports. ## Use cases - Post-production engineers converting broadcast TTML files into WebVTT for HTML5 video players. - Localization managers transforming translated SRT files into IMSC 1.0.1 compliant TTML delivery packages. - Content creators converting YouTube SBV caption files into standard SRT or WebVTT subtitles. ## Frequently asked questions ### How does the converter handle drop-frame timecodes? It calculates true drop-frame intervals for 29.97 DF and 59.94 DF, omitting frame numbers at minute boundaries (except every tenth minute) to match broadcast timecode. ### How are TTML styles converted to WebVTT? TTML styling attributes like colors and font families are mapped into WebVTT ::cue CSS blocks, and cue text is wrapped in matching class spans. ### What is verified during IMSC 1.0.1 checks? The validator checks profile declarations, frame-rate definitions, aspect ratio parameters, permitted style attributes, and per-cue chronological consistency. ### Which subtitle formats are supported? The tool supports bidirectional conversion among SRT, WebVTT, TTML (SMPTE and clock time), and YouTube SBV formats. ### Can I upload subtitle files directly? 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