Decklink SDI ! ccextractor ! x264

[Sebastian Dröge]

On Wed, 2019-03-27 at 09:10 -0600, John P Poet wrote:
> 
> > There is ccconverter, but it doesn't operate on metas but a
> > packetised closed caption stream, so you'd have to use ccextractor
> > to split the metas into a stand-alone stream, then convert the type
> > to what x264enc needs, then put the result back on buffers as metas
> > with cccombiner.
> 
> 
> Can you provide me with a theoretical pipeline that would be used for
> this?  That would help me get on the right path and figure out what
> the current state actually is, and what would need to be done.

What Tim suggested indeed would work and is what I tried a while ago.
You'd put a ccextractor after the decklinkvideosrc, pass the video
stream through a queue and then to cccombiner, pass the CC stream
through a queue, ccconverter and a capsfilter (to enforce the correct
CC format) and then also to cccombiner. And after cccombiner you place
x264enc and the remainder of your pipeline.

> > So much for the theory. In practice some things may not be fully
> > implemented yet. Your mileage may vary. Good luck :)
> 
> Can GStreamer output captions to a MCC or SRT file?  Begin able to
> take the data from decklinkvideosrc and write the captions out to a
> file would be a good first step in validating what is happening.

There's an MCC encoder/parser in gst-plugins-rs:
  https://gitlab.freedesktop.org/gstreamer/gst-plugins-rs/tree/master/gst-plugin-closedcaption

-- 
Sebastian Dröge, Centricular Ltd · https://www.centricular.com

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