RST vs SUB
A detailed comparison of reStructuredText and MicroDVD Subtitle — file size, quality, compatibility, and which format to choose for your workflow.
reStructuredText
Documents & TextRST (reStructuredText) is a lightweight markup language used in Python documentation.
About RST filesMicroDVD Subtitle
Documents & TextSUB (MicroDVD) is a subtitle format that uses frame numbers for timing instead of timestamps.
About SUB filesStrengths Comparison
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.
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
RST Limitations
- Syntax denser than Markdown — higher learning curve.
- Less widely adopted than Markdown outside Python world.
- Multiple directive dialects (Sphinx, Docutils, custom) create fragmentation.
- MyST (Markdown + Sphinx) has pulled many Python projects toward Markdown.
SUB 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.
- Superseded by SRT and ASS for editing and modern streaming.
Technical Specifications
| Specification | RST | SUB |
|---|---|---|
| MIME type | text/x-rst | text/x-microdvd (MicroDVD); image/vnd.dvb.subtitle (VobSub) |
| Extension | .rst | .sub (paired with .idx for VobSub) |
| Toolchain | Docutils, Sphinx, Read the Docs | — |
| Encoding | UTF-8 | — |
| Related formats | MyST (Markdown + RST directives) | — |
| Variants | — | MicroDVD (text), VobSub (bitmap) |
| Common conversion | — | OCR VobSub → SRT |
Typical File Sizes
RST
- API reference page 5-50 KB
- Sphinx project chapter 20-100 KB
- Full library documentation 500 KB - 10 MB
SUB
- MicroDVD .sub for 2-hour movie 50-100 KB
- VobSub .sub (2-hour movie) 1-10 MB
- VobSub .idx metadata 50-200 KB
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Frequently Asked Questions
RST (reStructuredText) is a document format used to store paginated text, with optional formatting, tables, images, hyperlinks, headers and footers. It sits in the documents & text family and is typically associated with a specific office suite or publishing pipeline that defined the format and ships the canonical reader.
SUB (MicroDVD Subtitle) is a document format used to store paginated text, with optional formatting, tables, images, hyperlinks, headers and footers. It sits in the documents & text family and is typically associated with a specific office suite or publishing pipeline that defined the format and ships the canonical reader.
Modern office suites — Microsoft Word, Google Docs, LibreOffice Writer, Apple Pages — open most RST files with reasonable fidelity. If your installed software does not support RST, convert to DOCX or PDF first using KaijuConverter; both open in virtually every reader, including free online viewers.
Modern office suites — Microsoft Word, Google Docs, LibreOffice Writer, Apple Pages — open most SUB files with reasonable fidelity. If your installed software does not support SUB, convert to DOCX or PDF first using KaijuConverter; both open in virtually every reader, including free online viewers.
Upload the RST to KaijuConverter and pick DOCX, PDF, ODT, RTF, HTML, Markdown, or plain text. Our pipeline runs LibreOffice headlessly plus pandoc for text formats — the same engines behind professional document pipelines. Styles, tables, images, and hyperlinks survive the conversion intact.
Yes, to a high degree. Standard fonts, headings, lists, tables, images, hyperlinks and page structure transfer cleanly. Custom fonts substitute to the closest match if not embedded; obscure layout features unique to RST (frames, legacy macros) may flatten to static content in the target format.