Add your SUB file
Drop one or more .sub files onto the converter above, or browse for them. They load into browser memory only — nothing is uploaded, so there is no size-based pricing and no server queue.
SUB to DFXP
Converting a .sub file to .dfxp extracts the document's content from its office package into a portable form. Free, private, and validated — the file never leaves your browser.
Private for supported formats — processed in your browser
Runs on your deviceConvert supported files
Drop SUB files here
Batch files can each use a different output. Nothing uploads for local conversions.
Working inputs include camera RAW, browser-local audio/video, PDF, CBZ/CBR comics, office documents, ebooks, markup, 3D models, structured text, images, and archives.About converting MicroDVD subtitles to DFXP timed text
Converting a .sub file to .dfxp extracts the document's content from its office package into a portable form. A .sub file in the MicroDVD convention is a frame-based subtitle list: every line reads {startFrame}{endFrame}text, with a pipe character separating the lines inside one cue. Because the timing is expressed in frames rather than milliseconds, a MicroDVD file only means anything alongside the frame rate of the video it was timed to.
A .dfxp file is a TTML document written to the Distribution Format Exchange Profile — the profile the W3C defined for handing finished captions to a distributor. The extension signals the profile; the contents are ordinary TTML, which is why the same parser reads both. For this route the practical draw is accepted by name across a wide set of streaming ingest specifications and fully TTML, so any TTML tool can read and validate it — balanced against the distinct extension implies a distinct format and regularly confuses tooling, which is worth knowing before you commit a large batch.
Why convert SUB to DFXP?
The practical trigger for this conversion is usually a mismatch: with .sub, meaningless without the correct frame rate; the wrong value drifts the whole file. Switching to .dfxp buys you accepted by name across a wide set of streaming ingest specifications, which is why it is the better fit for delivering captions to a platform whose spec names DFXP by extension. Because the conversion runs locally, trying it costs nothing but a few seconds of compute on your own machine.
SUB vs DFXP at a glance
| Aspect | MicroDVD subtitles (.sub) | DFXP timed text (.dfxp) |
|---|---|---|
| Format type | Text-based — characters and structure, so there is no visual quality loss | Text-based — characters and structure, so there is no visual quality loss |
| How it stores data | each cue is one line: {startFrame}{endFrame} followed by the text, with | separating multiple display lines | the document is TTML: a <tt> root, a <body>/<div> structure, and <p> cues with begin and end attributes |
| Strongest at | playing back subtitles that were timed against a specific video rip | delivering captions to a platform whose spec names DFXP by extension |
| Weak spot | meaningless without the correct frame rate; the wrong value drifts the whole file | the distinct extension implies a distinct format and regularly confuses tooling |
| Metadata | there is no metadata section; the only header-like content is the frame-rate declaration, which is read on input and written on output | profile and parameter attributes are read for timing purposes only; styling and layout are not carried into caption targets that cannot express them |
Pick DFXP as the output
Select .dfxp in the output menu next to each file. The menu only offers targets this engine can genuinely produce, so if DFXP is selectable, the route is real and validated.
Convert on your device
Press Convert. The package is unzipped in memory and its XML content parsed locally; nothing is uploaded.
Verify and download
Each result is signature-checked before the download unlocks, so a failed encode can never masquerade as a valid DFXP file. Outputs keep the original filename with the .dfxp extension.
SUB to DFXP questions, answered
Will converting SUB to DFXP lose quality?
There is no visual quality to lose — sub is text-oriented and dfxp is text-oriented, so the question is structural fidelity. Text, ordering, and basic structure are preserved; complex layout, embedded objects, and styling beyond the target's model are simplified.
Is it private to convert SUB files here?
Yes — the .sub file is processed inside your browser tab and never uploaded. The package is unzipped in memory and its XML content parsed locally; nothing is uploaded. Close the tab and the file is gone from memory.
Where will the DFXP file work?
Streaming ingest pipelines, caption editors such as Subtitle Edit and CaptionMaker, and any TTML-aware library open .dfxp. Browsers and consumer players do not. Novus Convert reads it through the same hardened TTML parser used for .ttml — no document types, no external entities, no network access — and writes any of the twelve timed-text targets.
Will the DFXP file be bigger or smaller than my SUB?
It depends on the content: the document is TTML: a <tt> root, a <body>/<div> structure, and <p> cues with begin and end attributes. Convert one representative file first and compare before batch-processing a large set.
What happens to the metadata in my SUB file?
In .sub, there is no metadata section; the only header-like content is the frame-rate declaration, which is read on input and written on output. Re-encoding through the browser pipeline does not carry embedded metadata into the output, which doubles as a privacy scrub — check the exported file if you specifically need tags preserved.
Can I convert DFXP back to SUB?
Yes — the reverse route exists as a separate tool. Bear in mind that round-tripping .sub → .dfxp → .sub is not a perfect undo when any lossy step is involved; keep your original if fidelity matters.