VANC (Ancillary data, e.g. captions)

[Sebastian Dröge]

On Di, 2016-05-17 at 22:24 +0000, John P Poet wrote:
> 
> What is the best way to handle VANC?
> 
> An ex-coworker came up with a patch to add VANC processing to
> GStreamer version 1.2.3 for Blackmagic cards.   Unfortunately, he
> never pushed that code upstream before he left.
> 
> With his patch, the VANC was extracted from the Blackmagic driver and
> then pushed onto the gstreamer pipeline -- similar to the way video
> and audio was pushed onto the pipeline in V1.2.3 of Gstreamer.  He
> then added a VANC sink pad to ffmpegenc to encode the captions.
> 
> Since version 1.2.3, the GStreamer Blackmagic support has been
> completely re-written, and it no longer works the same way.  I would
> like to take the work that my ex-coworker did, and adapt it to the
> latest version of GStreamer, but I am unclear on what the proper
> approach would be.  Should I effectively clone gstdecklinkvideosrc
> into gstdecklinkvancsrc and tweak it as appropriate?
> 
> I don't see any established support for processing captions.  Has a
> roadmap been defined?  If I get this working, I am hoping that my
> work will be accepted upstream, so I would like some guidance on how
> to do it right.

There's
  https://bugzilla.gnome.org/show_bug.cgi?id=766419
for adding specific "processing captions": timecodes :)

To me it seems like VANC shouldn't be a separate stream but also
GstMeta on the audio/video buffers. As it is metadata about those and
not an independently useful streams.

What do you think? What are your use cases for VANC?

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

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