subconv - Ruby SCC (EIA-608) to WebVTT subtitle converter

This Ruby Gem provides conversion of subtitle files in the .scc (Scenarist Closed Captions) format to the more modern WebVTT format that can be used in browsers with HTML5 videos.

The processing is modeled after this paper by the W3C.

Installation

gem install subconv

Usage

$ subconv --help
Usage: subconv [options] SCC-FILE
    -o, --out-file FILENAME          Write output to specified file instead of stdout
    -f, --fps FPS                    Assume given video fps for timecode calculation (default: 29.97)
    -c, --no-color                   Remove all color information from output
    -F, --no-flash                   Remove all flash (blinking) information from output
    -s, --simple-positions           Convert to simple top/bottom center-aligned captions
    -p, --keep-paint-on              Keep paint-on captions, i.e. do not combine them into pop-on cues
    -h, --help                       Show this help message and quit.

The API can also be used programmatically, the bin/subconv file is just an example for this.

Supported features

EIA-608 parsing and conversion to WebVTT
- Pop-on captions
- Paint-on captions
- Full positioning
- All special characters defined in the FCC standard
- All extended (Western European) characters defined in EIA-608-B
- All colors
- Italics
- Underline
- Flash
Paint-on to pop-on caption conversion (by combining similar cues)
Optional removal of certain features during the conversion
- Color
- Flash
- Conversion of fine position information to just top/bottom center

Note that with all features removed, most browsers can display the captions as-is, but for the colors etc. to work you will need to include a stylesheet that defines appropriate styles. The one used in the W3C report is packaged here in dist/eia608.css. Even then, browsers currently do not correctly support numerous settings yet. Infamously, Firefox can not apply classes/styles inside cues at all.

Unsupported features

Roll-up captions
EIA-708