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Reference Glossary

Closed captioning file

A closed captioning file (commonly SCC, encoding EIA-608/CEA-708 data) is a toggleable caption track; FCC rules require broadcast captions to meet accuracy, synchronicity, completeness, and placement standards.

Last verified

7 Aug 2026

figures re-checked

Method

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Why it matters in a DAM

Caption files must stay version-linked to the exact video edit they were timed against — if an editor trims or re-cuts a video after captions were finalized, the caption file's timecodes drift out of sync with the new edit, and a DAM that doesn't tie caption-file versions to video-edit versions will keep serving a stale caption file against the re-cut video, which produces an out-of-sync result that fails FCC quality standards if it airs.

A worked example

Format SCC (CEA-608)
Linked video version promo_v3_final.mov
Sync status Matches current edit
FCC quality check Accuracy, synchronicity, completeness, placement — passed

Common mistake

A video gets re-edited (trimmed for a shorter cut) after the closed captions were finalized, but the DAM keeps the original SCC file linked to the new version because caption files aren't version-locked to the specific video edit they were timed against, so the captions drift out of sync when the re-cut airs.

Closed captioning originated as broadcast data encoded directly into a television signal (EIA-608, later CEA-708 for digital broadcasts), and the SCC file format carries that same line-21 caption data as a standalone sidecar file synced to a video by timecode. Unlike open captions, closed captions can be switched on or off by the viewer, and unlike most subtitle formats, captions are meant to include non-dialogue audio information — sound effects, speaker identification, music cues — because their original purpose is accessibility for viewers who are deaf or hard of hearing, not translation.

The FCC’s 2014 quality standards, which took effect in 2015, formalized four requirements for U.S. television captions: accuracy (captions must correctly convey dialogue and sound), synchronicity (captions must be timed to match the dialogue without significant lag), completeness (captions must run the entire length of the program), and placement (captions must not obscure other important on-screen information). All four depend on the caption file staying correctly matched to the specific video edit it was created for — a caption file is only synchronous and complete relative to the exact cut it was timed against, which is why a DAM handling broadcast-bound video needs to version-lock caption files to video edits rather than treating them as loosely associated attachments.

  • Accuracy — captions correctly convey dialogue and sound
  • Synchronicity — captions are timed to match the dialogue without significant lag
  • Completeness — captions run the entire length of the program
  • Placement — captions don’t obscure other important on-screen information

Frequently asked

What's the difference between closed captions and open captions?

Closed captions are a separate track a viewer can toggle on or off; open captions are burned directly into the video image and can't be turned off, which matters for accessibility compliance since a viewer needs the option to disable captions if they don't want them.

What is SCC and why is it still used for broadcast?

SCC (Scenarist Closed Captions) encodes CEA-608/708 line-21 caption data in the format broadcast equipment expects, which is why it remains the standard delivery format for content going to traditional television broadcast even as web-native formats gain adoption.

What does the FCC's synchronicity requirement actually mean in practice?

Captions must be timed so they don't lag noticeably behind the corresponding dialogue or sound — a caption file that was accurate for an earlier cut of a video but wasn't re-timed after a re-edit will fail this requirement even if the text itself is still correct.

Do closed captions need to describe sound effects, not just dialogue?

Yes — accessibility-focused closed captions are expected to convey non-dialogue audio information like sound effects, music, and speaker changes, which is a key difference from most subtitle files that assume the viewer can already hear the audio.

Why does a DAM need to version-lock caption files to specific video edits?

Because a caption file's timecodes are only accurate against the exact cut it was created for — if the video gets trimmed or re-edited afterward, the same caption file will drift out of sync unless the DAM either blocks the mismatch or flags that captions need re-timing.

Are FCC caption quality standards only for broadcast television, or do they also apply to streaming?

The FCC's 2014 quality standards were adopted specifically for television programming; separate but related requirements apply to online video that was previously shown on TV under the CVAA, though the specific obligations and enforcement differ by platform and content type.

Sources