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SCC Format ( Scenarist Closed Caption )

The file is double-spaced, with data lines alternating with blank lines. The first line identifies the format and version--it needs to be exactly like this. The third and subsequent alternating lines start with the timecode and are followed by the data.

The timecode is in SMPTE format, which is either hours:minutes:seconds:frames for non-dropframe timebase or hours:minutes:seconds;frames for dropframe timebase. Both are 29.97 frames per second, but dropframe timebase accomplishes the fractional framerate by using 30 frames per second and skipping the first two frames each minute for nine out of every ten minutes (non-dropframe timebase simply runs the clock at exactly 29.97 frames per second). Use the same format you encoded your video with. Here's a hint: if it came from a broadcast source, it's probably dropframe, while if you created it from scratch, it's probably non-dropframe.

The data is made up of two-byte hexidecimal words, separated from each other by spaces and from the timecode by a tab character. The data uses only seven out of every eight bits of each byte, with the high bit used to satisfy odd parity--adding up all the bits has to result in an odd number, or the closed caption decoder will reject the byte as corrupt data. The major exception is ITV, which not only doesn't enforce odd parity, it also uses a slightly different character set than captions, text or XDS.

User may be able to obtain sample SCC files within this SDK.

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