Closed Captioning

The orignally used for the NTSC format in broadcast and release media, closed captions or subtitling data that allowed various consumer equipment to super-impose dialog subtitles over video.

It should be noted that while it was orignally for NTSC, PAL release media also has it, however PAL broadcast mainly used Teletext for subtitle data and on LaserDiscs of course.

Genarating Closed Caption Signals

Ali1234's Raspberry Pi Teltext/Closed Captions genarator can genarate an live composite signal with complient cea608 CC signals.

Reading Closed Caption Data

ld-process-vbi can read the Closed Caption data anyware in the VBI space.

Simply run the command on your .tbc file:

ld-process-vbi my_media_source.tbc

This will generate the Closed Caption fields data in the JSON metadata file.

Generating a SCC file

SCC is the Scenarist Closed Caption format V1.0 and uses .scc as the file extension. SCC is the only supported output from ld-decode tools as the format keeps the closed caption data intact (i.e. no commands or other special data is lost in the convertion).

To generate an SCC file use a command line such as:

ld-export-metadata --closed-captions /home/sdi/Decodes/cinder/cindys1.scc /home/sdi/Decodes/cinder/cindys1.tbc.json

This will create the required SCC file (this file is readable in any text editor if you'd like to view the contents).

Converting the SCC file to SRT

SRT is a format commonly used in tools such as the VLC media player and allows the player to overlay subtitles during video playback:

To convert the SCC format file into SRT (and other common formats) you can use a tool like ttconv. The tool has an online test page allowing you to upload the SCC file and get a converted SRT in return:

This tool is available from the ttconv github, the test page is available from this link

SCCYOU

https://github.com/amiaopensource/sccyou

sccyou is a bash script that allows easy generation of standard .srt files