Doug’s Q-Tips – How to Integrate Captioning

All new-gen QMODs have the ability to import captioning data for inclusion with each channel’s program.  SDI video has the ability to embed 708/608 digital captioning, while other inputs can provide captioning data on the unit’s composite video output.

The QMOD-SDI 2 illustrates the two ways for integrating captioning.


SDI is the only format that can provide digital captioning, which is embedded in the SDI stream.  SD-SDI provides 608 captioning, which is equivalent to Line 21 analog captioning. HD-SDI can embed 708 digital captioning, that has more options for presentation and colors. For SDI captioning, go to the CC Source menu, and select SDI 1 or SDI 2.

One would expect that HDMI, DVI, VGA, and Component video can also provide captioning data – but no. They are consumer standards that never thought about commercial integration or ADA regulations. The only video format that can carry captioning data is good old Composite video. It’s called Line 21 captioning as it’s carried in the vertical interval, on line 21.

The video inputs on the new QMODs are multi-purpose, as different sites have different needs. For captioning, connect the Composite output from an HDTV tuner or cable/satellite receiver. Go to the CC Source menu and select Video 1 or Video 2.

It’s possible for a site to have SDI video, but line 21 captioning. For example, a sports arena may have an in-house SDI feed that doesn’t have embedded captioning. They use an older analog captioning system, and want to insert the live captioning into the QMOD program. No problem. Just select one of the Video inputs as a captioning source.