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Calibration Question?

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Caleb Armstrong
Calibration Question?
on Mar 3, 2008 at 1:31:32 pm

Recently I shot a training program in my studio that appeared fine while we were shooting, but after outputting for broadcast I began noticing some noise issues throughout the entire broadcast.

At first glance I was ready to chalk it up to some excessive noise in the blue channel; I had used a curtain in the background with a bluish-grey tint, and used a blue leko on a set piece. In retrospect, the background could have had more light thrown on it, and that could be the source of the noise, but I noticed that, when I put smpte color bars up, the edges of the bars were almost jagged, like there was information drifting between the channels or something. the monitors are older, for sure, and don't have comb filters built in.

I'm not an engineer, and the engineer that I spoke with told me that he didn't see anything wrong on our scopes. Still, the jagged lines between the smpte bars concern me. If it were only the blue channel, then that's fine, but I noticed that it has started appearing regardless of what is in front of the camera.

Any suggestions on what this could be or how to resolve my jagged color bars?

Thanks.



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Bob Zelin
Re: Calibration Question?
on Mar 4, 2008 at 2:25:07 am

without sending a "screen shot" of your scope, I can't answer the question. you have not specified if you are working in composite, component, or sdi (or hd-sdi), and what scope you are looking at.

If you are looking at a component or sdi or hd sdi signal, and have access to a component or sdi scope that has parade mode, you can see the noise for each channel of the camera.

IF you just have a composite waveform monitor, you can look at a red image or a blue image, and get a "general idea" if one tube, or chip, is noiser than the other, but this is not a comprehensive test.

You have not even stated what camera you are using, so I don't know if you have a one chip or 3 chip camera (or old tube camera).

composite video has jagged lines (it's called NTSC chroma crawl, and has been there for a long time - this is why beta component became so popular). without test equipment, and details on your system, a verbal diagnosis on this forum means nothing.

Bob Zelin





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Caleb Armstrong
Re: Calibration Question?
on Mar 4, 2008 at 7:16:05 pm

Bob, thanks for responding. I'm sorry for being so vague. Unfortunately the only images that I can provide you with are a screenshot of FCP's scopes with the bars coming through an AJA IO (Standard Definition), and a capture of the bars from FCP. The only means of actually getting a shot of my scopes would be using the crappy camera on my phone, and I don't have any means of getting the image off of the camera while I'm at work. I would be happy to upload pictures later at home, if you think that it would help.

We use three Ikegami HC-D57W cameras. We are a composite operation and strictly SD.

Here is the AJA capture of the bars:



Here is a close-up of a portion of the bars:



And here is a terrible close-up screencap of the bars with final cut scopes up:



I'm sorry that I don't have more for you. I'm a contractor for the government, and the support around here tends to be lacking, which is why I'm reaching out to the pros. If I can get a decent picture of my scopes I'll post them later. Thanks again for your time.



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Bob Zelin
Re: Calibration Question?
on Mar 4, 2008 at 8:38:27 pm

Well my friend, welcome to NTSC video. This is commonly called NTSC chroma crawl. Back in the stone age (before Beta VTR's were invented, and people were using composite video switchers and VTR's), this is what everything looked like. And then the Sony BVW10, BVW15 and BVW40 came out (soon to follow by the BVW75, PVW2800, and the infamous UVW-1800). And LO AND BEHOLD, people saw ANALOG COMPONENT VIDEO, and the "ringing" that you see above in your video between GREEN and MAGENTA was GONE ! And guess what - it's gone in SDI (which is serial digital component), and it's gone in HD-SDI (which is HD serial digital component).

The "ringing" or jagged lines that you are seeing come from NTSC encoders that take the RGB signal and convert them into a composite video signal. When component video is used, you DONT GET THAT RINGING (or jagged lines). ITS ALWAYS BEEN THIS WAY, before AVID and FCP were even a thought in peoples minds.

You now understand why CAV, SDI and HD-SDI are the prefered way to work, and composite video is totally useless in 2008.

SO, how do you make a composite operation look better - you don't. Faroujda Laboratories spend decades working on products to improve NTSC composite, but the world changed, with new formats. When you watch TV at home, your local news TV station has all modern equipment, so you are used to looking at much better images that what you have at work.

bob Zelin




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Caleb Armstrong
Re: Calibration Question?
on Mar 4, 2008 at 11:17:46 pm

I guess I'll just have to accept that the Federal government will never be less than 10 years behind the curve.

Hey, thanks for all the input Bob, I really appreciate it!



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