608 / 708 Closed captions out Decklink SDI

[didikunz]

A few thoughts and ideas to this topic:

@asperi

The Play Out Server will just play file after file for a 24 hour schedule, no layers, no graphics- just one file ends, and the next file plays.

That is seldom true, as most of the stations have at least a bug layer. Sometimes they also need a second video layer for stuff like a push-back effect, where underneath it a advertisement graphic (or video) is revealed, that could also contain text/sound, that would need to go to the caption.

@asperi

…but pretty sure there is just a base layer with the main video/ captions that will pass, and stated in the manual that if you want captions to pass, they need to be on this layer where they are sent directly to the output and combined with the final output video.

We could add something like a MIXER command, that enables CC output on a layer, and disables it on all others. In the scenario where we have a second layer (push-back etc.) the play-out controller would issue another command to switch to the secondary layer.

@hreinnbeck

Perhaps it would be simpler to parse EIA/CEA 608/708 from the ffmpeg producer to OSC (or other protocol) and that could be picked up by a separate service for insertion.

That could be a way to go. That MIXER command I mentioned above would then enable the output to OSC (or other protocoll).

Then a completely independent software could do the insertion of the 608/708 CC or Teletext or maybe even open captions. It would need a separate channel (Decklink cards channel), because AFAIK only one software at a time is able to get access to a Decklink channel. But that is not a big issue, as one could use a Duo 2 and use a spare channel for this.

For Caspar’s side we only would need to implement that special MIXER command and the extraction and sending out of the CC data, but could leave most of the frames pipeline untouched.

The implementation of the inserter could be left to a separate (GitHub) community.

What do you guys think?