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Decklink 4k Extreme and Closed Captioning

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mat cav
Decklink 4k Extreme and Closed Captioning
on May 1, 2013 at 3:24:23 pm

Also asked on the CC forum but maybe this is a better place..

Documentation on CC is very limited from BlackMagic, basically non-extant... So any help would be great.

I am doing SD captures using the Decklink 4k Extremes component in from my Sony Beta SP deck. I know the tape has line 21 CC - 608, yet I cannot confirm that this is being capture and preserved. Have tried captures in Media Express and in Premiere CS6, when playing out the composite into a TV no CC displays. If running component directly from my deck to the TV I see CC, so it seems the Decklink is stripping it out. I know there are some line settings in the BMD Desktop Video "capture VANC input line.. Defaults to:
18 - capture to movie file line 1
19 - capture to movie file line 2
20 - capture to movie file line 3

So the decklink moved the captions on encode? and now that cannot be played back to tv and view CC? Why?

Any help or insight would be great. Thanks-

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Glenn Sakatch
Re: Decklink 4k Extreme and Closed Captioning
on May 2, 2013 at 1:49:36 pm

Been a while since i had to play with SD cc, but (from memory) if you capture it into your box, uncompressed, and you can still see the white data strips up top, i'll bet you are good. Can you not output it back to a work tape and see if it is there off of the deck playout again? I wouldn't think you would have to do any kind of "line tweaking". SD cc is usually there if those white data bits are there and are moving around.

SD cc was usually pretty easy to work with. We used to capture it in Avid, crop to expose just the cc and overlay it back of different video and re-output all the time without issue.

HD cc is where it became a pain in the butt.


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Bo Higbee
Re: Decklink 4k Extreme and Closed Captioning
on May 4, 2013 at 3:14:33 pm

Hope this is of help ....

It's been about 6-8 months, but....

I used to capture off BetaSP with a variety of BMD cards ... from Decklink PCI SD cards to Decklink SDI PCIe using a Aja analogue to SDI converter box ... everything worked ... but, ONLY IF I used the BMD Media Express capture software that comes with the driver downloads.

One thing I did notice was of the 6 or 7 BMD cards I bought off Ebay and played with, I think one card had a intermittent CC capture problem when I would play the file out via another one of my cards, but for the most part all cards captured and played each others captured files with CC correctly.

My work flow was to have the Beta deck output loop directly through (input to output) the Decklink card so I could see the video loop- through WITH THE CAPTIONS on my TV/monitor with the captions turned on ... then I would use the BMD Media Express capture software to capture the video with captions and play back the BMD captures to verify the CC signal.

Things started to get funky with captions when using older BMD cards with the newer Adobe Premiere CS5.5 and CS6 and the evolution of BMD drivers around that time.

The only new drivers that I could get to work were:
DesktopVideo 9.5.3 for CS5.5
.. and ...
DesktopVideo 9.6.1 for CS5.5+CS6

Beyond ver. 9.6.1 ... I stopped trying and went to digital file delivery of my Fishing Show using the Firewire output to tape of my show from PPro CS5.5 and PPro CS6 timelines (since the new PPro can output captions to DV tape) .... and then I turn around and RE-CAPTURE that DV tape with the embedded captions (with a couple seconds of slack at beginning and end of show) ... and upload that re-captured 6.5GB file with the captions in the VANC area of the DV signal to the TV station server.

I discovered that it's the TV station and THEIR conversion software (in my case they use Carbon Coder software and Harris Nexio broadcast servers using the .LXF format) that is important for this whole CC business ... and NOT that you bought someone's $5,000 software package to do caption embedding when your file is going to be re-converted AGAIN at the TV station to their "House Format" anyway.

It turns out that Carbon Coder (and TeleStream encoders, etc.) can work with a variety of CC methods to make a server based file for broadcast servers. All you have to do is find out what your station uses and do research on the web to find out what formats the software will convert ... with the CC data intact.

Recently, I've been able to encode my captioned shows using the MainConcept Mpeg encoding built into Sony Vegas Video Pro (ver. 10e and above) into SD and HD files and BOTH test shows have been broadcast recently with captions ... all because the station uses Carbon Coder conversion software which can see the CC within this particular MainConcept encoded file and transcode as needed.

Ohh ... forgot: The settings for line 18, 19, 20, 21 etc ... they are only there IF you want to just capture that info off tape and run caption info through a CC decoder, etc. and not the actual video image.

DON'T play with any settings regarding these lines .... just capture the SD 720x486 picture area ONLY and it should work. (The captions are in the active 720x486 picture area.)

Long ... not a direct answer, but hope this helps.

Good luck.

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