How to Convert SRT to SCC Closed Captions for Broadcast | AllSubConverter
SRT works for almost every video player, but North American broadcast television and many streaming services require SCC (Scenarist Closed Captioning) files for compliance with FCC closed-captioning rules. If you are delivering captions to a TV station, a cable network, or a compliance workflow, you will likely need to convert SRT to SCC. This guide explains what SCC is, how it differs from SRT, and what to expect during conversion.
What Is SCC?
SCC is the industry-standard file format for delivering CEA-608 (Line 21) closed captions. Instead of readable text, an SCC file encodes caption data as hex byte pairs, each preceded by an SMPTE timecode in HH:MM:SS:FF format at 29.97 frames per second. Every SCC file begins with the header line Scenarist_SCC V1.0.
This encoding exists because broadcast captions are not subtitles drawn on screen. They are data embedded in the video signal, decoded by the television, and rendered according to viewer settings. That is why the format is so different from plain-text subtitle files.
SCC turns readable subtitles into broadcast caption data. The words and timing survive; the file format changes completely.
Key Differences Between SRT and SCC
SRT uses millisecond timing (HH:MM:SS,mmm) and stores text directly. SCC uses frame-based SMPTE timecode (HH:MM:SS:FF) at 29.97fps and stores caption commands as hex. Because the timecode is frame-based, millisecond timing is rounded to the nearest frame, a granularity of about 33 milliseconds.
SCC captions also follow CEA-608 rules, including roll-up and pop-on display modes and a fixed character grid. Styling and positioning are handled by the decoder rather than stored in the data, so SRT styling does not carry over.
How to Convert SRT to SCC
Use our free SRT to SCC converter. The tool reads your SRT file, converts the timing to 29.97fps SMPTE timecode, encodes the caption text as CEA-608 hex byte pairs, and writes a valid SCC file with the required header. The dialogue and approximate timing are preserved.
After conversion, verify the output against your delivery specification, because broadcasters often have strict requirements for caption placement, character limits, and timing offsets.
Frequently Asked Questions
Is timing exact after converting to SCC?
Not to the millisecond. SCC timing is frame-based at 29.97fps, so it has roughly 33ms granularity. The converter rounds each cue to the nearest frame, which is the best any SCC file can represent.
Do I need SCC for YouTube or web video?
No. Web platforms use SRT, VTT, or SBV. SCC is for traditional broadcast television and cable delivery. For YouTube, convert SRT to SBV or upload SRT directly instead.
Can I convert SCC back to SRT?
Yes. Use the SCC to SRT converter to decode the caption data back into readable, timed text.