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I want to be able to stream live TV but also include the closed captions. My workflow is to use a Blackmagic Designs Decklink card (video source is SDI) and use VLC to capture and transcode the video, then send that to a Wowza server to be packetized for HTTP streaming. I have this working for Video, but I cannot figure out how to get the closed captions to appear in my player. I am using a VLC Player, Quicktime, Flowplayer on a web page, iPad, and iPhone to view the streams, none of them show the closed captioning in the source video. The closed captions are both 608 and 708. I have spent the last 3 days reading everything I can about vlc and closed captions, wowza and closed captions, and x264 and closed captions, vbi, teltext, and even subtitles, but I am no where closer than when I started. I sincerely that someone here will be able to help me.

I am using a core i7 with 4GB ram, runign ubuntu 10.04 64bit. I compiled vlc with the following:

./configure  '--enable-xvideo' '--enable-sdl' '--enable-avcodec' '--enable-avformat' '--enable-swscale' '--enable-mad' '--enable-a52' '--enable-libmpeg2' '--enable-dvdnav' '--enable-faad' '--enable-vorbis' '--enable-ogg' '--enable-theora' '--enable-mkv' '--enable-flac' '--enable-caca' '--enable-alsa' '--enable-qt4' '--enable-ncurses' '--enable-realrtsp' '--enable-twolame' '--enable-real' '--enable-x264' '--with-decklink-sdk=/home/bimls/bmd/Blackmagic_Decklink_SDK_9.6.4/Linux' '--enable-zvbi'

I use the following to capture and stream the live video:

cvlc decklink:// --decklink-card-index="0" --decklink-mode="ntsc" --rtsp-timeout 0 --sout='#transcode{venc=x264{subme=1, ref=1, bframes=16, b-adapt=1, bpyramid=none, weightp=0 }, vcodec=h264, vb=1300, acodec=mp4a, ab=96, threads=4}:rtp{dst=127.0.0.1:8888,mux=ts}'' --vbi-page=100 --no-vbi-opaque --vbi-position=0

Some of the question I have are:

  • Is this the proper way to get the closed captions to appear? if not please what am I doing wrong?
  • How does one know what vbi-page to look for as the range seems to be "--vbi-page integer [-2147483648 .. 2147483647]>"
  • Does transcoding destroy closed caption data?

So, Please any help will be greatly appreciated! Thank you!

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Did you check the scodec option? It's for sub-titles though. There is limited support for CC in VLC, but I think they are working on improving this area to meet the FCC requirements (EIA-608 decoder). I don't know anything about status however. You can extract them into SRT files though. Perhaps there is a way to insert the srt back into the stream as cc.. –  Ken Fyrstenberg Dec 14 '12 at 22:24
    
Btw, the vbi-page is for Teletext, ie. page number - not the same as CC. –  Ken Fyrstenberg Dec 14 '12 at 22:29
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1 Answer 1

There isn't support for taking the closed caption data from SDI and embedding it in the video stream. That's why it doesn't work.

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Can you include a reference that supports your answer? –  JoshP Dec 19 '12 at 2:40
    
Well I wrote support for adding user data such as captions in x264 a long time ago and VLC doesn't use this API. –  Kieran Kunhya Dec 21 '12 at 1:50
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