MMegaConvert

Convert SUB to JSON

Free online SUB to JSON converter. No signup required.

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Max file size: 100 MB

When to convert SUB to JSON

Use this conversion when your destination needs JSON and you have a SUB source. Keep the original so you can compare the result or try another supported format.

Check the output in your target application. Format conversion may change unsupported features, metadata or precision; retain the original file as your reference.

SUB vs JSON: Format Comparison

Side-by-side comparison of the source and target formats.

PropertySUB (Source)JSON (Target)
Extension.sub.json
Full NameMicroDVD SubtitleJSON File
CompressionVariesVaries
File SizeVariesMedium
Best ForLegacy subtitle files for video contentWeb API request and response payloads (REST A…
Browser SupportVariesWide

How to Convert SUB to JSON

Follow these simple steps to convert your file in seconds.

  1. Choose a SUB file

    Select or drop one file up to 100 MB. Its extension must match this converter. Availability is checked before transfer.

  2. Convert to JSON

    Check the output in your target application. Format conversion may change unsupported features, metadata or precision; retain the original file as your reference.

  3. Download and check the result

    Use Download after conversion completes. Open the result and check its content, quality and formatting before sharing it. Download links expire one hour after upload finishes. Uploaded and converted files are removed automatically by regular cleanup. Files may become unavailable sooner when the service restarts.

Tips for Converting SUB to JSON

Practical advice to get the best results from this conversion.

Why this conversion is worth doing

MicroDVD Subtitle has a known limitation: frame-based timing requires knowledge of video frame rate for correct display. JSON File addresses this with a key advantage: native support in JavaScript and first-class parsing in virtually all programming languages. Converting from SUB to JSON is most worthwhile when this specific trade-off matters for the way you intend to use the file.

Match the format to the actual workflow

MicroDVD Subtitle is most commonly used for legacy subtitle files for video content, while JSON File is the standard for web api request and response payloads (rest apis). If your workflow is closer to the second pattern, converting makes sense. If you are still working in a context where SUB is the norm, converting may create unnecessary compatibility friction with collaborators or tools that expect the source format.

Watch for this limitation in the JSON output

JSON File has its own limitation worth understanding before you commit: no support for comments, making annotated configuration files difficult. After the conversion completes, open the JSON file and verify that this limitation does not affect your specific use case — for some workflows it is irrelevant; for others it can be a deal-breaker.

Match the subtitle format to your player or platform

Different players and platforms require specific subtitle formats. SRT is the most universally supported format for offline players. VTT (WebVTT) is the standard for HTML5 video on the web. ASS/SSA supports advanced styling but has limited player compatibility. Choose the format your target platform natively supports to avoid display issues.

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 File

application/json

JSON (JavaScript Object Notation) is a lightweight, text-based data interchange format derived from JavaScript object literal syntax. It supports nested objects, arrays, strings, numbers, booleans, and null values in a hierarchical structure. JSON has become the dominant data format for web APIs, configuration files, and modern application data exchange.

Advantages

  • Native support in JavaScript and first-class parsing in virtually all programming languages
  • Supports hierarchical nested data structures with objects and arrays
  • Human-readable and relatively compact compared to XML

Limitations

  • No support for comments, making annotated configuration files difficult
  • No native date, binary, or custom data type support
  • No schema enforcement by default, requiring external validation tools

Common Uses

  • Web API request and response payloads (REST APIs)
  • Application configuration files and settings
  • NoSQL database storage and document interchange

Frequently Asked Questions

Common questions about converting SUB to JSON.

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