How to add closed captioning to MPEG-2, QuickTime MOV, or AVI/DV for cable broadcast? I need to add closed captioning to a short video that will be broadcast on our cable TV system.  The cable system will accept MPEG-2, QuickTime MOV, or AVI/DV formats.  This is in the United States, and I'm guessing that we will need both EIA-608 and CEA-708 formats.  Because I am not actually producing the video itself, and I don't have it yet, I don't know whether it will be in a standard-definition or high-definition format.  I am presuming the latter, but information on either could be helpful.

What software (preferably free and/or open-source) can help with this task?  I have tried Google, and I have tried skimming the documentation of some of the packages out there (e.g., Kdenlive) to no avail.  I can use Linux or Windows software for sure, and I can probably find someone with OS X if needed.
You could check out these links to see if they provide what you need:

http://www.theneitherworld.com/mcpoodle/SCC_TOOLS/DOCS/SCC_TOOLS.HTML

Caption Maker Pro:

http://www.cpcweb.com/

And of course Scenarist and Encore, although both are DVD oriented you should be able to produce at least MPEG-2 with closed captions embedded:

http://www.rovicorp.com/products/distribution/content-production-tools/scenarist-bd.htm
http://www.adobe.com/products/encore.html


  Closed-captioning support
  
  Import line 21 files to add closed captions to your DVDs (NTSC titles
  only).