Convert SUB to SRT Online

Converting MicroDVD .sub to SRT: What This Tutorial Covers

A .sub file in the MicroDVD style does not store times at all — it stores frame numbers, like {1440}{1560}Come in.. SubRip (.srt) stores real clock times to the millisecond. So this is not a cosmetic re-wrap: every line has to be multiplied by a frame duration, and that number has to come from somewhere. This page walks through the conversion, shows exactly which parts of a MicroDVD file survive it, and tells you what to check before you use the result.

How to Convert SUB to SRT

1. Load Your .sub File: Click *� Upload .sub to pick the file, or paste the MicroDVD text straight into the Input (SUB) box — the character counter above the box confirms it landed. One file at a time; the picker is not a multi-select.
2. Check the Format Dropdowns: From format is already set to SUB and To format to SRT on this page. Both are 13-entry dropdowns, so you can retarget to VTT, SSA, TTML and the rest without leaving the page.
3. Click Convert: The button reads Convert →. The first click also pulls in the parser chunk, so it may say "Loading subsrt…" for a moment; after that conversions are instant.
4. Copy or Download the SRT: Use *� Copy for the clipboard or ⬇ Download .srt for a file. Your subtitle file is read by the browser and converted by JavaScript on this page.

Walk-through: The Frame Rate Question

MicroDVD's {start}{end} values are frame indices. Frame 1440 is one minute into a 24 fps film and 57.6 seconds into a 25 fps PAL transfer — same file, two different answers. There is no way to recover the right one from the numbers alone, which is why the format grew a convention: authoring tools write the frame rate onto the first line, as a pseudo-cue like {1}{1}23.976. FFmpeg's MicroDVD demuxer scans the first three lines for exactly that shape and accepts any value between 3 and 100 fps; if it finds none it falls back to 23.976, and exposes a subfps option so you can override.

This page's converter behaves differently, and it is worth knowing before you convert:

• It assumes 25 fps. That is the parser's built-in default, and there is no frame-rate control in the interface to change it.
• It does not read the first-line declaration. A {1}{1}23.976 header matches the ordinary cue pattern, so it comes through as a subtitle whose text is the literal string 23.976. Delete that line from your input before converting, or delete the first cue from the SRT afterwards.
• A 23.976 fps source therefore drifts. Reading 23.976 fps frames on a 25 fps assumption compresses the timeline by about 4.3% — roughly 2.6 seconds of drift per minute, accumulating.

Check the converted timeline against your video before you use it. MicroDVD timing scale is a defect we currently have open, so treat the numbers in the output as something to verify rather than trust. The cue text, the line breaks and the cue order come across faithfully; the timeline is the part that needs your eyes on it.

MicroDVD and SubRip Side by Side

Property	MicroDVD (.sub)	SubRip (.srt)
Timing unit	Frame numbers	Clock time, hh:mm:ss,mmm
Precision	One frame (40 ms at 25 fps)	1 millisecond
Frame rate needed to read it	Yes — external or first-line convention	No, times are absolute
Cue syntax	{start}{end}text on one line	Index, time range, then text lines
Line break inside a cue	| pipe character	A real newline
Styling	Inline codes: {y:i}, {y:b}, {y:u}, {c:$BBGGRR}	None in the spec; players widely accept <i>, <b>, <u>
Positioning	{P:x,y}	Not supported
Cue numbering	None	Sequential index required
Typical use today	Legacy DivX/Xvid rips, MicroDVD-era players	The universal interchange format

What Survives the Conversion

Element in the .sub	Result in the .srt
Cue text	Preserved verbatim
| line separator	Becomes a real line break inside the cue
Cue order and count	Preserved, renumbered from 1
Frame range	Recalculated into a clock time range — verify it
{y:i} / {y:b} / {y:u} style codes	Stripped, not translated to <i> / <b> / <u>
{c:$BBGGRR} colour, {f:} font, {s:} size	Stripped
{P:x,y} positioning	Stripped — SubRip has nowhere to put it
A cue with no text	Kept as an empty cue

Common Errors and How to Fix Them

• "No cues parsed from input. Check the format." — the parser found zero lines matching {digits}{digits}text. Usually the file is not MicroDVD at all: plenty of .sub files are SubViewer text, and a .sub sitting next to an .idx is VobSub, which is a stack of bitmap images with no text in it and needs OCR rather than conversion.
• The first subtitle reads 23.976 or 25 — that is the frame-rate header line being treated as a cue. Remove it from the input, or delete the first block of the output.
• The very first real subtitle is missing — a UTF-8 byte-order mark at the start of the file prevents line 1 from matching the cue pattern, so it is skipped silently. Re-save the .sub as UTF-8 without BOM, or paste the text into the input box instead of uploading, which sidesteps it.
• A cue you can see in the file is missing from the output — MicroDVD allows an open-ended cue written {1440}{}Text, meaning "until the next one". This parser requires digits in both braces and drops the line. Give it an explicit end frame.
• Everything converted, but the subtitles fire far too early — that is the timing scale issue described above. Check the output against the video before you commit to it.
• Accented characters came out as mojibake — old MicroDVD files are frequently in a legacy code page such as Windows-1250 rather than UTF-8. Re-save the source as UTF-8 in a text editor first; the browser reads the file as text and cannot guess a legacy encoding for you.

When This Doesn't Work

The one case no subtitle converter can rescue is VobSub. If your .sub is several megabytes and has an .idx file beside it, the subtitles are stored as rendered pictures ripped from a DVD — there is no text to extract, and you need OCR software such as Subtitle Edit or SubRip rather than a format converter. The quick check: open the file in a text editor. Real MicroDVD is readable ASCII full of curly braces; VobSub is binary noise. Likewise, if your goal is a plain reading transcript rather than a timed file, SUB to TXT drops the timing entirely and gives you just the dialogue.

Frequently Asked Questions

Why does my SUB to SRT conversion need a frame rate at all?

Because MicroDVD never stored one. Its {start}{end} numbers are positions in the video's frame sequence, so the only way to turn them into seconds is to divide by the frames-per-second the video actually runs at. SubRip stores absolute times, so once you have converted, the frame rate stops mattering — but you have to get it right at the moment of conversion.

What frame rate does this converter assume?

25 fps, unconditionally. That is the parser's built-in default and the interface exposes no control to change it. For context, FFmpeg's MicroDVD reader defaults to 23.976 fps instead when a file declares nothing, so the same file can legitimately produce two different timelines depending on which tool opens it.

Will italics and colours from my .sub file survive?

No. MicroDVD's inline codes — {y:i} for italic, {y:b} for bold, {c:$0000ff} for colour, {f:} for font, {s:} for size — are removed along with the braces, and are not rewritten as the <i> and <b> tags most SubRip players understand. You get clean unstyled text. If styling matters more than SubRip compatibility, SUB to SSA targets a format that can carry it, though this converter does not translate the codes there either.

What happens to the pipe character in a MicroDVD cue?

| is MicroDVD's line separator, and it becomes a genuine line break in the SRT cue. So {100}{200}Hello!|How are you? converts to a two-line subtitle rather than one line containing a stray pipe.

My .sub file has an .idx file next to it — will this work?

No, and that is worth catching early. That pairing is VobSub, the DVD subtitle format, where the .sub holds bitmap images of the subtitles instead of text. A text converter has nothing to read. You need OCR — Subtitle Edit is the usual free choice — to turn those pictures into characters first.

Is my subtitle file uploaded anywhere?

No. This converter is one of the pages that runs entirely in your browser: the file is read locally with the browser's own file-reading API, parsed by JavaScript on the page, and handed back to you as a download generated in memory. The converter code is fetched from us once; your subtitle file never is.

Does the SRT keep the same number of subtitles as the .sub?

Almost always, with three exceptions we can name precisely: a first line carrying a byte-order mark is skipped, an open-ended {1440}{} cue is skipped, and a first-line frame-rate declaration is added as an extra cue. Cues that do convert keep their original order and are renumbered from 1.

Which line endings does the SRT output use?

Windows-style CRLF, which is what the overwhelming majority of subtitle tooling expects and what SubRip files have historically used. Players on macOS and Linux read it without complaint.

Can I convert SRT back to MicroDVD afterwards?

Yes — SRT to SUB runs the reverse trip. Bear in mind it is not lossless in the round trip: the frame rate used to write the new .sub is an assumption again, and any styling you added to the SRT does not map onto MicroDVD's code system.