ATSC Closed Captioning

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ATSC Closed Captioning

mccrobie2000
I finally got my gst pipeline up and running for dvbsrc + video / audio /
captioning.  However, I've noticed both mpegvideoparse and avdec_mpeg2video
will add captioning data to the pipeline, resulting in double captions per
frame.

I've recompiled mpegvideoparse to exclude it's adding of caption data, but
am wondering if anyone else encountered the issue?  Perhaps I have something
wrong in my pipeline - see below.  If it can be optimized, I would
appreciate it.

I also have a pipeline for decklinkvideosrc closed captioning, which of
course, does not result in double captions per frame.

My background is captioning software, so I quite familiar with cc_data and
CDP, frame rates, etc.  I am new to gstreamer.

compiled from git
gst-launch-1.0 version 1.15.0
GStreamer 1.15.0 (GIT)
Unknown package origin


/opt/gstreamer/bin/gst-launch-1.0 -v \
dvbsrc frequency=531000000 modulation="QAM 256" delsys=atsc ! queue ! \
                tsparse ! tsdemux program-number=1006 name=demux \
        demux. ! queue ! video/mpeg ! mpegvideoparse ! avdec_mpeg2video !
tee name=dvideo ! videobin. \
        demux. ! queue ! audio/x-ac3  ! ac3parse ! avdec_ac3 ! queue !
audioconvert ! audio/x-raw,rate=48000,format=F32LE,channels=2 ! \
                audioresample ! pulsesink \
        dvideo. ! queue ! video/x-raw ! ccextractor !
closedcaption/x-cea-708,format=cc_data ! tee name=cdp ! \
                  queue ! cc708overlay name=videobin font-desc="DejaVu Sans
12" ! queue ! video/x-raw ! autovideosink \
        cdp. ! queue ! zmqsink endpoint=tcp://*:5557 bind=true




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Re: ATSC Closed Captioning

Tim Müller
On Thu, 2018-12-20 at 00:18 -0600, mccrobie2000 wrote:

Hi,

> I finally got my gst pipeline up and running for dvbsrc + video /
> audio / captioning.  However, I've noticed both mpegvideoparse and
> avdec_mpeg2video will add captioning data to the pipeline, resulting
> in double captions per frame.

Could you please file an issue in gitlab about that [*], in the gst-
libav project, then I'll have a look. Should be easy enough to fix.

Thanks!

Cheers
 Tim

[*] https://gstreamer.freedesktop.org/documentation/contribute/

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Tim Müller, Centricular Ltd - http://www.centricular.com

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Re: ATSC Closed Captioning

Dark_Knight
In reply to this post by mccrobie2000
Hello Could you please post a working dummy pipeline with CC elements?
I am not able to distinguish what CCoverlay and CCcombiner will do exactly,
Do we need to add any parsers in between , Please help with the above
queries .
Thank you.



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