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CC not displaying but detected. Can Scope/rasterizer find problem?

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jay agoglia
CC not displaying but detected. Can Scope/rasterizer find problem?
on Jan 15, 2013 at 2:46:30 pm

Hey Cow comm,

I would like to get some insight as to why a QT cosed captioning track is present and the captions do not display or play out.

QT7 sees the QT CC track
AJA CTR xchange see the CC

Neither will them play out.

During the process of working with the file: (EV encoding)
I saw and QC'd captions viewing the out put of all gear. From APR source file, to HD cam SR and back to APR again. I ran tests and am pretty confident that it has something to do with the source file (or possibly pipeline though tests would suggest otherwise)

Any thoughts on what to look into to help trouble shoot this. I have an evertz cc encoder and a tektronix web 7200 rasterizer to obtain specific caption/aux data info.

I am wondering what exactly on our tektronix unit could I look for
HD source file 1920x1080 29.97, APR


Thank you

Jason Agoglia
QC Manager
On The Spot Media


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Mark Spano
Re: CC not displaying but detected. Can Scope/rasterizer find problem?
on Jan 15, 2013 at 3:02:28 pm

Assuming you are using an AJA device to output the video, it's probably just that the VANC is not turned on for output. Go to the AJA Control Panel under Format and make sure VANC is checked. You can see it here (I have an IO Express):





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jay agoglia
Re: CC not displaying but detected. Can Scope/rasterizer find problem?
on Jan 15, 2013 at 3:19:02 pm

Hi Mark,

Thank you for the response. The VANC checkbox is checked and just checked to verify. I don't think I would have been able to see the captions play from the SR otherwise. Something is funky about the QT closed cap track in this file. I have a work around but would love to get to the bottom of this. Any other thoughts?

going) APR-AJA-HD teletrax-SR
back) SR- pipeline log and capture

FCP log and capture is the work around so either FCP is handling this specific error in the captions track better than pipeline, pipeline is corrupting the captions (again tests say otherwise), something is inherently corrupt on the source QT CC track.

I need more thoughts!

thank you

Jason Agoglia
QC Manager
On The Spot Media


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Mark Spano
Re: CC not displaying but detected. Can Scope/rasterizer find problem?
on Jan 15, 2013 at 3:30:32 pm

I'm just throwing darts here, but the only other thing I can think of is that somewhere along the way the caption data is moving to a different line in VANC than what the decoder is looking for. Then you might have a situation where the device detects caption data (some flag is ON) but won't display it because it doesn't know where to look for the essence of the data.



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