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Waveform Readings
We have a new studio and I’m somewhat new to broadcast. Our studio consists of GV Kayak running SDI to XDcam and IMX with IKE HL-60 Cameras and Tektronics Waveform monitor. Our stage is set at 100 ft candles. When shading the video I know that our black levels are to be set at 7.5 IRE. On our waveform we have the majority of the black at 7.5 but there are some small spikes that are going below 7.5. Is that a problem for Broadcast. If we raise the blacks so that there is absolutely nothing below 7.5 then the black levels are too light. Anybody have any info on this?
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7 Replies
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If you are looking at flat display, ou will have chroma information running below 7.5 and above 100% that is normal try not to allow it to get too far below or above. If the chroma starts to run too much below base line it can cause video breakup, because the signal can look at that and think it is sync and try to lock to it. &.5 black is a guide, and should be watched when looking at IRE settings.
Uh by the way reading your equipment setup, need any help?
Charlie
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Thanks for the info, we have a good crew that has former experience when it comes to shooting, but for actual Broadcasting we are still learning.
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Given that Charlie was a demo rep for Grass Valley and still has a HUGE love affair with their gear…I think he wants to work for you based on the toys in your sandbox….
Cheers,
Frank Otto
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Yea, but I doubt he wants to move to Branson.
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OK, ’nuff said. Forget my offer.
Charlie
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In the digital world you can now have your blacks go to 0 IRE. Just an FYI. Of course you should check with whomever you are delivering your product to, but that is what we set our levels to at the station I work at. (It is a very large one)
Ryan
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Devin,
7.5 setup only applies to NTSC analog outputs not SDI. There is no setup when dealing in SDI. I assume you are monitoring the SDI output of the switcher on the waveform monitor. You must also verify your monitor is set up properly when you have color bars displayed. The pulge and blue check must be set up right if you expect to make accurate black level and color shading decisions.
However you do not run your black levels flatline at 0 because you will be crushing the blacks.
You need to give yourself some headroom so running them at 1-2 millivolts is more ideal. However depending on what you are shooting in terms of contrast you may need to lower or higher the black level.
You should consider working with an experienced freelance video control operator for your multicamera shoots. This is the only way to obtain consistant quality camera shading as well as comply with broadcast standards.
Tony Salgado
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