SCC file format is mostly used for American Line 21 closed captions standard.
CEA-608 standard limits the number of characters per row to 32 so the default in Closed Captions mode is set to 32 CPL. 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.In
CEA-608 standard limits the way to delete 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.
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