Broadcast Subtitle Formats Explained: SCC, STL, DFXP/TTML and Friends

Quick reference

SCC — Scenarist Closed Captions

An .scc file wraps CEA-608/708 closed-caption data in timecoded commands — pop-on, roll-up, paint-on, positioning. It has been the default closed-caption deliverable in broadcast and disc workflows for decades, which is why archives are full of it and why it keeps resurfacing in repurposing projects.

The quirk: timecode comes in 29.97 drop-frame (semicolons) and non-drop (colons) variants, and the two are not interchangeable — mix them up and every cue drifts.

Convert SCC to SRT →

STL — EBU STL

The European Broadcasting Union's binary subtitle exchange format, common across European broadcast delivery. Each cue carries in/out timecodes plus alignment and formatting codes in a compact binary layout built for transmission, not for editing.

The quirk: it's binary, so text editors show garbage — and the .stl extension is shared with stereolithography 3D-print files, which are a completely different animal.

Convert STL to SRT →

DFXP — Timed Text distribution profile

DFXP (Distribution Format Exchange Profile) is a TTML profile built for distribution: XML cues with begin/end times and optional styling, typically delivered as .dfxp or .xml. It's the interchange format you meet when captions move between tooling and streaming delivery pipelines.

The quirk: styling is part of the format, but SRT has no styling model — expect clean text plus timing out the other side.

Convert DFXP to SRT →

TTML — Timed Text Markup Language

The W3C's XML timed-text format: cues in timed elements inside a timed-text document, shipped in profiles such as DFXP. Broadcast and streaming pipelines use it for interchange up and down the chain.

The quirk: "a TTML file" can mean several profile variants under several extensions (.ttml, .dfxp, .xml). The structure inside matters more than the name on the outside.

Convert TTML to SRT →

SBV — SubViewer

A minimal plain-text format: a start and end timestamp on one line, caption text below, a blank line between cues. It's a lightweight export option in video platforms and small editing tools — easy to produce, easy to break.

The quirk: no styling or positioning at all. What you write is what every player shows.

Convert SBV to SRT →

SRT in one paragraph

SRT (SubRip Text) is the lingua franca of subtitle files: numbered cues, HH:MM:SS,mmm --> HH:MM:SS,mmm timestamps, plain text. Practically every player, editor and platform reads it — which is why "convert to SRT" is the first step of nearly every subtitle-repurposing workflow, and why every converter on this page targets it. The SRTKit homepage converter also handles VTT, ASS/SSA, SUB, LRC and plain text.

Which format do you actually need?

• Delivering against a broadcast or streaming spec → the spec names the format (often SCC or STL) and the frame rate. Follow the spec, and convert at the edges where your tools meet it.
• Editing or reusing captions → SRT or VTT. Plain text, universal support, easy diffs.
• Moving captions between tools and pipelines → TTML/DFXP when the tools speak XML timed text.
• Quick, throwaway captioning → SBV works, but don't build an archive on it.

Convert any of them to SRT, free

1. Pick the converter for your source SCC, STL, DFXP, TTML or SBV — each has a dedicated page below.
2. Upload the file No installation, no account. The format's quirks — drop-frame timecodes, binary structures, XML profiles — are handled in the conversion.
3. Download clean SRT Numbered cues, standard timestamps, timing intact.

More than a handful of files? The batch converter queues a whole folder in one pass. And choosing between tools in general? The SubtitleTools alternatives comparison covers pricing, API and repair side by side.