MMegaConvert

Convert SUB to VTT

Free online SUB to VTT converter. No signup required.

Drag & drop your file here

or click to browse

Max file size: 100 MB

Advertisement

How to Convert SUB to VTT

Follow these simple steps to convert your file in seconds.

  1. 1

    Upload your .sub file

    Drag and drop your .sub file into the upload area, or click "Browse" to select it from your device. Your file is uploaded securely and processed on our servers.

  2. 2

    Click "Convert to VTT"

    Once your file is uploaded, press the convert button to start the SUB to VTT conversion process.

  3. 3

    Wait for the conversion to complete

    The conversion usually takes just a few seconds. You can see the progress in real time while your file is being processed.

  4. 4

    Download your converted .vtt file

    When the conversion is finished, click the download button to save your new .vtt file. The file is ready to use immediately.

Understanding SUB and VTT Formats

Learn about the source and target file formats to understand what happens during conversion.

Source Format

MicroDVD Subtitle

text/x-sub

SUB (MicroDVD Subtitle) is a frame-based subtitle format that uses frame numbers rather than timestamps for timing synchronization. Each line contains start and end frame numbers enclosed in curly braces followed by the subtitle text, with pipe characters separating multiple display lines. SUB requires knowing the video frame rate to correctly synchronize subtitle display timing.

Advantages

  • Frame-accurate timing that precisely matches video frame boundaries
  • Simple format that is easy to parse and generate programmatically
  • Supported by many popular media players including VLC

Limitations

  • Frame-based timing requires knowledge of video frame rate for correct display
  • Changing the video frame rate misaligns all subtitle timing
  • Less intuitive than timestamp-based formats for manual editing

Common Uses

  • Legacy subtitle files for video content
  • Frame-accurate subtitle synchronization for specific video encodes
  • Subtitle conversion source for timestamp-based format output

Target Format

WebVTT Subtitle

text/vtt

WebVTT (Web Video Text Tracks) is the W3C standard subtitle and caption format designed for use with HTML5 video elements. It is based on SRT with additional features including CSS-based styling, cue positioning, vertical text support, and chapter markers. WebVTT is the only subtitle format natively supported by all modern web browsers for HTML5 video playback.

Advantages

  • W3C standard natively supported by all modern web browsers
  • Supports CSS styling, positioning, and vertical text
  • Includes metadata regions for accessible closed captioning

Limitations

  • Not as widely supported by desktop media players as SRT
  • Styling features are inconsistently implemented across browsers
  • More complex than SRT for simple subtitle use cases

Common Uses

  • HTML5 web video subtitles and closed captions
  • Streaming platform subtitle delivery (HLS and DASH)
  • Accessible web video captions meeting WCAG guidelines

Frequently Asked Questions

Common questions about converting SUB to VTT.

Related Conversions

Explore other conversions related to SUB and VTT.

Advertisement