CONVERT
SUB → RST
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Fast, secure SUB to RST conversion. No registration required.
Situation. SUB is a document format oriented around a particular office suite or publishing pipeline. Solution: a RST, produced below. Converting SUB to RST online saves installing office suites you use once a year. Upload the document, let the server render it through the same pipeline large publishers use, and download a polished RST that keeps its original structure and typography. Context: SUB is a document format oriented around a particular office suite or publishing pipeline. RST is a document format oriented around a particular office suite or publishing pipeline.
MicroDVD Subtitle
Source formatSUB (MicroDVD) is a subtitle format that uses frame numbers for timing instead of timestamps.
reStructuredText
Target formatRST (reStructuredText) is a lightweight markup language used in Python documentation.
Why convert SUB to RST
The driver for a SUB to RST conversion is almost always the downstream audience: the editor, archivist, signer or reader who expects a RST. Doing the conversion in a proper rendering pipeline, rather than hoping the receiving tool will figure it out, avoids layout drift and font substitutions.
HOW TO CONVERT
SUB → RST
Provide the document
Select a SUB file. Very large documents (100+ pages) may take a few extra seconds to render completely.
Render to RST
LibreOffice plus supporting filters translate the SUB into a fully-formed RST with no structural drift.
Save the result
The converted RST streams back over HTTPS; open in the target application to verify formatting.
Common Use Cases
Share across platforms
Send RST files to anyone without worrying about whether they have the right software for SUB.
Embed in documents
Drop RST output into Word, Google Docs, PowerPoint, Notion or a website without conversion warnings.
Optimize size
RST often produces smaller files than SUB for web, email and storage.
Archive & future-proof
Store in a widely-supported format that will still open on future operating systems without legacy plugins.
SUB vs RST — Strengths and limitations
What each format does best, and where it falls short.
SUB Strengths
- VobSub preserves DVD subtitle appearance exactly.
- MicroDVD is trivially editable text.
- Universal player support (VLC, mpv, MPC).
- Historical format for DVD-era subtitle preservation.
Limitations
- Bitmap subtitles (VobSub) cannot be edited as text.
- MicroDVD frame-based timing breaks on framerate changes.
- Two incompatible formats sharing one extension causes confusion.
RST Strengths
- Rich directives for admonitions, code, math, and custom elements.
- Cross-references work within and across documents.
- Sphinx ecosystem offers best-in-class Python docs output.
- Standardized as part of Python PEP infrastructure.
- Plain text, version-controllable.
Limitations
- Syntax denser than Markdown — higher learning curve.
- Less widely adopted than Markdown outside Python world.
- Multiple directive dialects (Sphinx, Docutils, custom) create fragmentation.
SUB vs RST — Technical specifications
Side-by-side comparison of the technical details.
SUB
- MIME type
- text/x-microdvd (MicroDVD); image/vnd.dvb.subtitle (VobSub)
- Extension
- .sub (paired with .idx for VobSub)
- Variants
- MicroDVD (text), VobSub (bitmap)
- Common conversion
- OCR VobSub → SRT
RST
- MIME type
- text/x-rst
- Extension
- .rst
- Toolchain
- Docutils, Sphinx, Read the Docs
- Encoding
- UTF-8
- Related formats
- MyST (Markdown + RST directives)
| Specification | SUB | RST |
|---|---|---|
| MIME type | text/x-microdvd (MicroDVD); image/vnd.dvb.subtitle (VobSub) | text/x-rst |
| Extension | .sub (paired with .idx for VobSub) | .rst |
| Variants | MicroDVD (text), VobSub (bitmap) | — |
| Common conversion | OCR VobSub → SRT | — |
| Toolchain | — | Docutils, Sphinx, Read the Docs |
| Encoding | — | UTF-8 |
| Related formats | — | MyST (Markdown + RST directives) |
SUB vs RST — Typical file sizes
Approximate file sizes for common scenarios.
SUB
- MicroDVD .sub for 2-hour movie 50-100 KB
- VobSub .sub (2-hour movie) 1-10 MB
- VobSub .idx metadata 50-200 KB
RST
- API reference page 5-50 KB
- Sphinx project chapter 20-100 KB
- Full library documentation 500 KB - 10 MB
Quality & Compatibility
The conversion preserves document structure rather than pixel-perfect rendering: a paragraph in SUB is a paragraph in RST, not a bitmap snapshot. That means you can still edit and search the RST. If you need exact visual fidelity (for legal or print workflows), export to PDF as the final step.
Tips for Best Results
- Run a spell-check in the RST after conversion — occasionally hyphenation or language tagging shifts and typos become invisible to the original checker.
- Include fallback generic fonts (sans-serif, serif) in your style definitions so the RST degrades gracefully when a font is missing on a viewer device.
- For archive-quality output, export to PDF/A after converting to RST; this locks the document against future rendering drift.
Frequently Asked Questions
Yes, as long as the fonts are standard (system fonts or common office fonts like Arial, Calibri, Times, Helvetica). Custom corporate fonts survive if they are embedded in the source document; otherwise the conversion substitutes the closest available match, which can shift line breaks by a character or two.
Yes. Inline images are embedded into the RST at full resolution, editable tables become native RST tables, and hyperlinks keep their URLs. Complex features unique to SUB — macros, form fields, track-changes — are mapped where an equivalent exists in RST and flattened into static content otherwise.
All uploads go over TLS, files are processed in isolated containers and both the source and the output are deleted within two hours. No account is required, file contents are never indexed or used for training, and the paid plan adds a signable data-processing agreement for regulated workflows.
Related comparisons
See these formats side by side to understand which fits your use case best.
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Read guideSecure & Private Conversion
Your files are encrypted during transfer, processed in isolated containers, and automatically deleted within 60 minutes. We never read, share, or store your data.