SCC (Scenarist Closed Captions)

Owned by Alex Yoffe
Last updated: Nov 20, 2020
2 min read

SCC file format is mostly used for American Line 21 closed captions standard.
As opposed to typical subtitle formats, which contain IN and OUT timecodes per subtitle event, SCC only include the IN timecodes. However, those are not the actual caption display time.

The timecodes define when the following characters will start to be transmitted to caption buffer and only two characters can be transmitted within one video frame.

The CEA-608 specification works in a way that two characters are transported within one video frame and when all characters are transported to the buffer, a special character is sent to display the complete caption. Therefore the IN timecodes visible in the SCC file will never correspond to the IN timecodes in the subtitle editor. The IN timecodes in the SCC file are calculated so that for every two codes, one frame is subtracted from the original timecode.

CEA-608 standard limits the number of characters per row to 32 so the default in Closed Captions mode is set to 32 CPL.

The way to set the OUT timecode for a caption is to send a special code to clear the screen and this character will have the OUT timecode from the caption file.

Example of SCC file structure:

Scenarist_SCC V1.0 01:00:33:21 9420 9470 9723 c445 cd4f 20c4 75f2 61f4 e9ef 6e20 62ef f4f4 ef6d 20e3 e56e f4e5 f280 942c 8080 8080 942f 01:00:40:15 942c 01:00:42:24 9420 94d6 97a2 c445 cd4f e5f2 20d0 ec61 e3e5 6480 94f2 97a2 52e9 6768 f420 4a75 73f4 e9e6 e9e5 6420 a843 c252 2980 942c 8080 8080 942f 01:00:44:23 9420 9454 97a2 c445 cd4f 20d0 ec61 e3e5 6480 9470 52e9 6768 f420 4a75 73f4 e9e6 e9e5 6420 a84c c252 2980 942c 8080 8080 942f 01:00:46:07 9420 94d6 9723 c445 cd4f f420 d0ec 61e3 e564 94f4 97a2 43e5 6ef4 e5f2 204a 7573 f4e9 e6e9 e564 20a8 52c2 4329 942c 8080 8080 942f 01:00:49:11 942c