MMegaConvert

Convert SUB to JSON

Free online SUB to JSON converter. No signup required.

Drag & drop your file here

or click to browse

Max file size: 100 MB

Advertisement

How to Convert SUB to JSON

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 JSON"

    Once your file is uploaded, press the convert button to start the SUB to JSON 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 .json file

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

Understanding SUB and JSON 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

JSON Subtitle

application/json

JSON-based subtitle formats store timed text data in structured JSON objects, commonly used by web applications, speech-to-text services, and modern video platforms. Various JSON subtitle schemas exist, including those used by YouTube auto-captions, Amazon Transcribe, and custom web video players. JSON subtitles can include rich metadata such as speaker identification, confidence scores, and word-level timing.

Advantages

  • Structured data format that is easy to process programmatically
  • Can include rich metadata like speaker IDs, confidence scores, and word timing
  • Native integration with web applications and JavaScript-based video players

Limitations

  • No single standard schema; varies across platforms and services
  • Not directly supported by traditional desktop media players
  • More verbose than SRT or VTT for simple timed text content

Common Uses

  • Speech-to-text service output (AWS Transcribe, Google Cloud Speech)
  • YouTube auto-generated caption data
  • Custom web video player subtitle delivery via APIs

Frequently Asked Questions

Common questions about converting SUB to JSON.

Related Conversions

Explore other conversions related to SUB and JSON.

Advertisement