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.vtt

WebVTT Subtitle

Subtitles & Captions

VTT is WebVTT timed text used for web subtitles/captions. It includes a WEBVTT header and its own timestamp syntax; renaming SRT is not sufficient. Manage it separately from the video.

What it is used for
Web subtitles and captions
What the file contains
Text
All sections, questions and sources

Content reviewed： · Editor：Kai

Opening steps

Choose your environment or purpose to see its steps.

Inspect WebVTT structure

Headers and timestamp syntax differ from SRT.

  1. Open a copy in a text editor.
  2. Inspect the WEBVTT header, separators and timestamps.
  3. Check timing order and UTF-8 text.
Load into video or a web page

Validate both file loading and subtitle activation.

  1. Load through a compatible player or video text track.
  2. For web use, inspect URL, text/vtt serving and access requirements.
  3. Select captions and compare text/timing.
Convert to SRT or another format

Position/style information may not transfer.

  1. Import a copy into a subtitle editor.
  2. Export separately in a supported target format.
  3. Compare timings, breaks and required styling.

Menu labels and support vary by app, OS and version. Preserve the original before making changes.

Troubleshooting by symptom

  • Web loading fails: check URL, access, text/vtt delivery and applicable cross-origin settings.
  • Invalid cues: inspect the header, timestamps, blank lines and cue boundaries.
  • Different appearance: test positioning/style support in the actual rendering environment.
  • Renamed SRT fails: convert the header and timestamp syntax.
  • Loaded but invisible: inspect track selection and cue times.
  • Cross-origin load fails: inspect access/CORS requirements.

VTT → SRT

  1. Use a subtitle exporter to transfer cue text/times, not just rename.
  2. Review discarded WebVTT-specific settings/notes and test synchronization.
  3. Validate cue times and destination rendering as well as the header.

SRT may not retain positioning, styling or metadata.

Check loading, selection and cues in order

Inspect resource loading, MIME type, track activation and valid cue timing.

Cross-origin delivery also requires suitable server access settings.

Source for these steps：W3C · WebVTT: The Web Video Text Tracks Format / VideoLAN · Subtitles — VLC desktop user documentation / Aegisub Project · Exporting

Check which presentation features survive

Other formats may not reproduce WebVTT placement/styles; inspect important cues in the destination.

Retain source VTT and video for text/timing comparison.

Source for these steps：W3C · WebVTT: The Web Video Text Tracks Format / VideoLAN · Subtitles — VLC desktop user documentation / Aegisub Project · Exporting

Related-format differences

Related-format differences
FormatMain roleWhat to check
VTTWeb timed textWEBVTT/UTF-8
SRTBasic captionsPresentation differences
ASSRich subtitle stylingPlacement/fonts

Handling and security

Review caption URL/content visibility; avoid exposing confidential conversations in public directories.

Questions and answers

Does it need a WEBVTT header?

The format has defined syntax including its header.

Can I reuse SRT timestamps unchanged?

Convert syntax differences such as fractional separators.

Must it use the video’s server?

Separate delivery can work with suitable access/cross-origin settings.

Is VTT only for subtitles?

WebVTT supports other timed-text uses; inspect the intended track kind.

Is replacing commas with dots sufficient?

Headers, cue structure and settings can differ; use supported export.

Format facts: name, steward and MIME type
Formal name
Web Video Text Tracks (WebVTT)
Steward / specification
W3C
MIME type
text/vtt

Primary and official sources