TTML vs SCC: Which Format Is Right for You?
A complete comparison of Timed Text Markup Language (TTML) and Scenarist Closed Captioning (SCC), covering structure, timestamps, styling, platform support, and best use cases.
TTML (Timed Text Markup Language) and SCC (Scenarist Closed Captioning) serve different roles in the subtitle ecosystem. Timed Text Markup Language is designed for professional subtitle delivery, streaming compliance. Scenarist Closed Captioning is designed for fcc-compliant broadcast caption delivery. Understanding their differences helps you choose the right format for your workflow and avoid compatibility problems.
TTML vs SCC at a Glance
| Feature | TTML (Timed Text Markup Language) | SCC (Scenarist Closed Captioning) |
|---|---|---|
| File extension | .ttml | .scc |
| Designed for | Broadcast, streaming platforms, professional workflows | North American broadcast TV (CEA-608 Line 21) |
| Timestamp format | X.YYYs (seconds) or HH:MM:SS.mmm (clock) | HH:MM:SS:FF (SMPTE timecode, 29.97fps) |
| Time precision | Millisecond (3 digits) or better | Frame-based (29.97fps, ~33ms granularity) |
| Styling support | Extensive (CSS-like, regions, animation) | None in data, display controlled by decoder |
| Header required | XML declaration and root with namespaces | Scenarist_SCC V1.0 header required |
| Positioning | Full region-based positioning | Fixed grid positions (CEA-608 roll-up/pop-on) |
| Multi-line breaks | tags within elements | Multiple hex bytes encode position and breaks |
| Standardized | W3C / SMPTE standardized (TTML 1.0, TTML2, IMSC) | ANSI/SCTE standard (CEA-608) |
| Browser support | Moderate (via JavaScript players, not native HTML5) | Poor (requires caption decoder) |
| Encoding | UTF-8 (always) | ASCII (CEA-608 character set) |
| Primary use case | Professional subtitle delivery, streaming compliance | FCC-compliant broadcast caption delivery |
Key Differences Explained
Timestamp and Timing
TTML uses x.yyys (seconds) or hh:mm:ss.mmm (clock). SCC uses hh:mm:ss:ff (smpte timecode, 29.97fps). TTML offers millisecond (3 digits) or better precision, while SCC works at frame-based (29.97fps, ~33ms granularity) precision. When converting between these formats, some timing precision may be lost due to the different granularity.
Structure and Syntax
TTML files use xml document with and sections. Each cue follows the pattern:
text
in xml. In contrast, SCC files use timecode line followed by space-delimited hex pairs, where each cue looks like: smpte timecode tab-separated from hex byte pairs. The structural difference means conversion requires parsing and reformatting, not a simple text replacement.Styling and Visual Control
TTML provides extensive (css-like, regions, animation). SCC provides none in data, display controlled by decoder. TTML has stronger styling support, making it the better choice when visual appearance matters.
Platform and Player Support
TTML is industry standard for netflix, amazon, apple tv. SCC is required for us broadcast and fcc compliance. Their browser and device support profiles differ significantly, which is often the deciding factor when choosing between them.
When to Use TTML
Choose TTML when your priority is professional subtitle delivery, streaming compliance. It excels in netflix, amazon prime, apple tv, broadcast and was w3c timed text working group, based on xml. TTML's biggest advantage is its rich styling capabilities. Its main limitation is that it complex xml structure, large file size, steep learning curve.
When to Use SCC
Choose SCC when you need fcc-compliant broadcast caption delivery. It is designed for us broadcast tv, cable, fcc compliance and was developed for scenarist dvd authoring, based on cea-608. SCC's standout strength is its specialized role in its target use case. Be aware that it ascii-only, complex hex encoding, no styling in data.
Converting Between TTML and SCC
Our free TTML to SCC converter handles the structural and timing differences automatically. The converter translates TTML timing to SCC timing, with minimal rounding where needed. Styling that the target format cannot represent is normalized or stripped, so you always get valid, ready-to-use output.
Frequently Asked Questions
Is TTML better than SCC?
Neither format is universally better. TTML is better for professional subtitle delivery, streaming compliance. SCC is better for fcc-compliant broadcast caption delivery. Choose based on your target platform and workflow, not on which format is technically superior.
Can I convert TTML to SCC without losing quality?
Yes. Text content is always preserved during conversion. Timing is preserved to the target format precision, with minimal rounding at the centisecond or frame level where needed. Styling features that the target does not support are dropped, but the subtitle text and timing remain accurate.
Which format is more widely supported?
SCC has broader support across players and devices. TTML works well with moderate (via javascript players, not native html5), while SCC works with poor (requires caption decoder). If you are unsure which format to use, SCC is usually the safer choice for maximum compatibility.
Are TTML and SCC files compatible?
Not directly. TTML and SCC use different file structures and timestamp formats. A player that supports one may not support the other. Use a converter to switch between them. Most modern subtitle editors and our converter can handle the conversion in both directions.