What quality should I expect from the JSON output?

Our converter preserves as much fidelity as JSON File allows. Where MicroDVD Subtitle carries information that JSON File cannot represent, that information is mapped to the closest equivalent (for example, color spaces, codec parameters, or metadata fields). For most everyday uses the result is indistinguishable from the source.

Are my subtitle timings preserved exactly when converting SUB to JSON?

Yes. Start times, end times, and durations are copied with millisecond precision. If the source uses frame-based timing rather than millisecond timing, we use the file's declared frame rate to convert — verify the result against your video, especially for long files where small timing errors accumulate. Styling (colours, positioning) is preserved when both formats support it; JSON File may strip styles that have no equivalent.

What file size should I expect for the JSON output?

The output size depends on the content and the compression characteristics of JSON File. In most cases the JSON file will be in the same ballpark as your SUB input, with differences driven by how each format encodes data. There is no fixed ratio — the converter does not change quality settings unless you ask it to.

When should I convert SUB to JSON instead of staying with SUB?

Convert when the application, device, or workflow you are targeting prefers JSON File over MicroDVD Subtitle. If your current SUB file already opens and behaves correctly everywhere you need it to, there is no benefit to converting — keep the original. The most common reasons to switch are compatibility (a tool only accepts JSON), distribution (recipients expect JSON), or feature requirements specific to JSON File.

What is the maximum SUB file size I can convert?

MegaConvert accepts SUB files up to 100 MB on the free service, which is enough for the vast majority of real-world MicroDVD Subtitle files. If you have a larger file (typical for high-resolution video or uncompressed audio), please contact us — we can sometimes accommodate larger uploads for legitimate use cases.

Is my SUB file safe and private when I upload it?

Yes. Your SUB file is uploaded over HTTPS, processed in an isolated job environment, and deleted from our servers within one hour. We do not read, index, store, or share the contents of your file. No account is required, so the upload is not associated with a personal identity. See our privacy policy for the full details.

Convert SUB to JSON

Free online SUB to JSON converter. No signup required.

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Max file size: 100 MB

Why Convert SUB to JSON?

Understand when and why this conversion makes sense for your workflow.

Converting MicroDVD Subtitle to JSON File ensures your subtitle or caption file works correctly with your target video player, streaming platform, or editing tool. Subtitle formats differ in how they encode timing information, styling, positioning, and special characters. A subtitle file that displays perfectly in one player may fail entirely in another, making format conversion essential for any video production or distribution workflow.

MicroDVD Subtitle has a known limitation: frame-based timing requires knowledge of video frame rate for correct display. In contrast, JSON File offers a key advantage: native support in JavaScript and first-class parsing in virtually all programming languages. While MicroDVD Subtitle is commonly used for legacy subtitle files for video content, JSON File is better suited for web api request and response payloads (rest apis).

Convert your SUB subtitle file to JSON with MegaConvert and ensure your captions display correctly in every player and platform you target.

SUB vs JSON: Format Comparison

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

Property	SUB (Source)	JSON (Target)
Extension	.sub	.json
Full Name	MicroDVD Subtitle	JSON File
Compression	Varies	Varies
File Size	Varies	Medium
Best For	Legacy subtitle files for video content	Web API request and response payloads (REST A…
Browser Support	Varies	Wide

How to Convert SUB to JSON

Follow these simple steps to convert your file in seconds.

Upload your SUB subtitle file
Choose your .sub subtitle file. UTF-8 encoded files are strongly preferred — Windows-1252 or other legacy encodings can corrupt non-Latin characters during conversion. The file picker accepts any size of subtitle file you are likely to encounter.
Click "Convert to JSON"
Press convert. Each subtitle cue is parsed from the MicroDVD Subtitle source — start time, end time, text, and any styling — and re-emitted in JSON File format. Timings are preserved with millisecond precision; styles are mapped to their closest JSON File equivalent.
Wait for the conversion to complete
The conversion usually takes just a few seconds. The progress bar updates in real time while your MicroDVD Subtitle file is processed and the new JSON File file is generated.
Download your .json file
When the conversion finishes, click the download link to save the new JSON File file to your computer. The file is yours — no watermarks, no expiration on the file itself, and no MegaConvert account is required to download it.

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.

Related Conversions

Explore other conversions related to SUB and JSON.

Other conversions from SUB

SUB to SRT SUB to ASS SUB to SSA SUB to VTT

Other conversions to JSON

SRT to JSON ASS to JSON SSA to JSON VTT to JSON

Convert SUB to JSON

Why Convert SUB to JSON?

SUB vs JSON: Format Comparison

How to Convert SUB to JSON

Upload your SUB subtitle file

Click "Convert to JSON"

Wait for the conversion to complete

Download your .json file

Tips for Converting SUB to JSON

Why this conversion is worth doing

Match the format to the actual workflow

Watch for this limitation in the JSON output

Match the subtitle format to your player or platform

Understanding SUB and JSON Formats

MicroDVD Subtitle

Advantages

Limitations

Common Uses

JSON File

Advantages

Limitations

Common Uses

Frequently Asked Questions

What quality should I expect from the JSON output?

Are my subtitle timings preserved exactly when converting SUB to JSON?

What file size should I expect for the JSON output?

When should I convert SUB to JSON instead of staying with SUB?

What is the maximum SUB file size I can convert?

Is my SUB file safe and private when I upload it?

Related Conversions

Other conversions from SUB

Other conversions to JSON