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IRE Black level at 0 (zero)?

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Khashyar Darvich
IRE Black level at 0 (zero)?
on May 19, 2007 at 11:33:43 pm

Hi Everyone,

I am sending a BetaSP master screening tape to a film festival, that asked for:

"Zero IRE black level (setup)


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walter biscardi
Re: IRE Black level at 0 (zero)?
on May 19, 2007 at 11:39:44 pm

[Khashyar Darvich] "
My question is since I did color correction and contrast/brightness with my NTSC monitor based on 7.5 ire black on the color bars, how can they set up the tape properly when they project it as the festival?"


They are going to project it based on your bars or possibly not even on that. Depends on the festival. Some have good engineers who set up each film, some have a button pusher who just loads the tape and whatever it is, it is.

Generally when projecting via a large theatrical projector, you want 0 blacks or the entire image will just have a greyish, washed out look throughout. It probably won't look exactly like you CC'd it though.

Walter Biscardi, Jr.
http://www.biscardicreative.com
HD Editorial & Animation for Broadcast and independent productions.

All Things Apple Podcast! http://cowcast.creativecow.net/all_things_apple/index.html

Read my blog! http://blogs.creativecow.net/WalterBiscardi


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Khashyar Darvich
Re: IRE Black level at 0 (zero)?
on May 20, 2007 at 12:17:57 am

Thanks for the feedback, Walter.

So, did I do what they asked by setting the Kona output to zero IRE, even though I adjusted the contrast and color correction based on the 7.5 black IRE level on the Final Cut Pro color bars?

Is that what they are asking for?

Also, they asked for "


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walter biscardi
Re: IRE Black level at 0 (zero)?
on May 20, 2007 at 12:22:42 am

[Khashyar Darvich] "So, did I do what they asked by setting the Kona output to zero IRE, even though I adjusted the contrast and color correction based on the 7.5 black IRE level on the Final Cut Pro color bars?"

What they were asking for were all your video levels to be at 0 black, not 7.5. If you used the Levels Filter to bring all your blacks to 7.5, your video will still look washed out. You want to adjust all your video levels down to 0 black, which is what we use in digital and HD video.

[Khashyar Darvich] "Also, they asked for "


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Khashyar Darvich
Re: IRE Black level at 0 (zero)?
on May 20, 2007 at 12:49:33 am

Thanks for your feedback and information, Walter..

By changing the output within my Kona control panel from 7.5 IDE to "0" IDE, did I do what the festival had asked:

"Zero IRE black level (setup)


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Khashyar Darvich
Re: IRE Black level at 0 (zero)?
on May 20, 2007 at 2:07:44 am

Hi Walter,

I just want to make sure that I set the black IDe level to zero on the tape.

Do I do this using the "Analog Black Level" setting in the "setup" section of the Kona control panel?

If I choose "0 IRE (Japan)", will this be the proper way?

Thanks for sharing your experience and expertise.

Khashyar


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Khashyar Darvich
Re: IRE Black level at 0 (zero)?
on May 20, 2007 at 2:22:08 am

I was reading the Final Cut Pro Bible and I think that I am understanding this better (please correct me if I am wrong).

On the Kona control panel, of you select "7.5" as the black level, then it will not outout any black lower than 7.5 IRE.

If you select "0", then black levels from 0 to 7.5 will also be exported through the Kona onto the tape deck.

Do I understand this correctly?

If this is true, then when the festival was asking for a "zero IRE setting," then by selecting "0 IRE" on the Kona control panel, this is accomplishing this.

Please verify that this is correct so that I won't need to rent my BetaSP deck beyond the weekend :)

Thanks,

Khashyar


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Bob Zelin
Re: IRE Black level at 0 (zero)?
on May 20, 2007 at 11:39:37 am

Dear Khashyar,

I fully understand your dilema from these questions. These were the most common questions when serial digital video came out. I will try to make this simple for you, and please understand that you can only do so much with the equipment that you have. There is a lack of understanding, which was not made simple by the SMPTE committee in the US, when SMPTE 259 and the associated standards for serial digital video, and it's levels as relating to analog were created.

NTSC color black has a setup level at 7.5 IRE, if you look at an analog waveform monitor. So, your Beta VTR will play back a color black signal at 7.5 IRE. Now, imagine that you take your tape, and play back the SAME tape in a Sony Digi Beta VTR (like a DVW-A500, or Walters J-30SDI). That SAME tape, will play back with a black level at ZERO IRE (no setup) if you observe the Serial Digital Output. SO, let me make this clear and simple. If you have a TV monitor that can show SDI and analog(like a Sony PVM-20L5/1) and a Waveform Monitor that can show SDI and analog (like a Leader LV5100D), you will see that with the SAME TAPE, from the SAME TAPE MACHINE, the SAME TAPE, with the SAME SIGNAL will display DIFFERENT BLACK LEVELS depending on weather you are looking at the analog signal, or the SDI digital signal. THIS IS CORRECT - THE SDI BLACK LEVEL will be "darker" than the analog signal, because it is 7.5 IRE lower than the same analog signal.

When you say that they want their audio level to be 20dB, this instantly indicates to me that they own a digi Beta VTR. You own a regular Beta VTR (like a UVW-1800). Your VU audio meters show ZERO level for tone. When you set a Beta 1800 for ZERO VU, this tape will show -20dBFS on a Sony DVW-A500 Digi beta machine, so -20 is the same as zero (confusing huh ?) - DO NOT SET YOUR ANALOG BETA VTR TO READ -20 !!!!

Because they own a Digi Beta VTR, your analog tape, which is playing it's black levels out at 7.5 IRE on your VTR, will play back on a Digi Beta VTR (from it's SDI video out ) at ZERO IRE. This means that you have to do NOTHING, and adjust NOTHING. If you drop your levels to ZERO on your analog machine, your picture will be dark at your place, and at the film festival.

NOW, your immediate question is "why would anyone create a standard like this - why would anyone do this ?" - the answer - the old fuddy duddy MORONS at the SMPTE COMITTEE, who have nothing to do all day long but create standards that don't apply to the real world. This is why you see SO MANY USELESS STANDARDS that many manufacturers tend to ignore over the years. That is why you see "Beta Component" levels, as opposed to SMPTE YPbPr", or SMPTE N10, or other nonsense like this, becuase Sony, and others could NOT GIVE A CRAP what the SMPTE COMMITTEE says, and does what they want. When SDI came out, there were only Sony D1 VTR's - no analog interface. Chroma levels were at 100 for the Pb an Pr components, black levels were at zero. No post house at the beginning was "mixing and matching" between analog and digital, because we were all supposed to "switch over" to D1 digital (the original SMPTE 259 days). When AVID came out with the
SDI card for the ABVB card set, all the editors wanted to "mix and match" analog footage wtih digital footage, and so the insanity began. The original Tektronix 601 SDI waveform monitor DID NOT EVEN HAVE MARKINGS FOR 75% on it, so there was NO WAY to even setup analog chroma on these early waveform monitors, because SMPTE WERE MORONS and did not consider that people wanted to use historical tapes (like Beta) on their digital edit systems.

To this day, when people switch back and forth between analog and digital (unless you actually use SMPTE N10 for your montior, which no one does), the black levels look DIFFERENT between the composite input and the SDI input from the SAME VTR, because of this stupidity.

TO SUMMARIZE - do nothing - just setup at 7.5 IRE for your blacks, and when they play your tape on their Digi Beta VTR, it will be at zero, and it will look fine. Set your tone for 0VU, and it will play back on their Digi Beta VTR at -20dBFS.

ps - I believe that AJA's first product was parallel to serial SDI converters for the early SDI VTR's.


Bob Zelin




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Khashyar Darvich
Re: IRE Black level at 0 (zero)?
on May 20, 2007 at 4:05:00 pm

Dear Bob,

Thank you for taking the time to write your detailed informative response.

I can see the confusion if they are using a DigiBeta deck to play my analog BetaSP tape.

I will just output to BetaSP with the normal 7.5 IRE setting, and calibrate tone to Zero.

What's really confusing is that they titled their specs email to me "BetaSP NTSC specs."

So, why would they state "Zero IRE black level (setup) do not setup to 7.5" ? doesn't this imply set up Zero IRE on the BetaSP deck that you are recording on?

Since I have rented a BetaSP deck this weekend, I will make another version of the tape with the normal 7.5 IRE setting.

Thanks again,

Khashyar


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David Roth Weiss
Re: IRE Black level at 0 (zero)?
on May 20, 2007 at 6:53:21 pm

[Khashyar Darvich] "So, why would they state "Zero IRE black level (setup) do not setup to 7.5" ?"

Those who can do, those who can't run festivals.



David Roth Weiss
Director/Editor/Post-production Supervisor
David Weiss Productions, Inc.
Los Angeles


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Bob Zelin
Re: IRE Black level at 0 (zero)?
on May 20, 2007 at 8:04:32 pm

you write -
I will just output to BetaSP with the normal 7.5 IRE setting, and calibrate tone to Zero.

REPLY - this is correct

you write -
What's really confusing is that they titled their specs email to me "BetaSP NTSC specs."

REPLY - I would be confused too. The only reason I ASSUME that they have a Digi Beta VTR is that they have specified a -20dB audio level, which is not indicated on any analog Sony VTR.


you write -
So, why would they state "Zero IRE black level (setup) do not setup to 7.5" ? doesn't this imply set up Zero IRE on the BetaSP deck that you are recording on?

REPLY - it means that they have a Digi Beta VTR. If they own an analog Beta VTR, and are requesting a O IRE setup level for blacks, they are going to "crush" the black details, and will get terrible looking pictures. I am sure that they own a Digi Beta VTR. I do not know why they specify the setup level, as it will be raised or lowered automatically, depending on the VTR they are playing back on.



Since I have rented a BetaSP deck this weekend, I will make another version of the tape with the normal 7.5 IRE setting

REPLY - you are doing the right thing.

Bob Zelin


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tony salgado
Re: IRE Black level at 0 (zero)?
on May 21, 2007 at 3:26:35 pm



The best thing to do is to call them directly and verify that the festival does indeed have a digi betacam vtr for playback.

Inquire if they will feed the projector via SDI , analog component or even worst NTSC composite.


Bob is dead on with his advice assuming the festival does have a digi beta vtr. If not there is some major confusion regarding what they are specifiying versus what you can delivery to them.


So when in doubt call them and try to get it in writing as to what specific vtr they will be using and how they will output it to the projector.



Tony Salgado


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Khashyar Darvich
Re: IRE Black level at 0 (zero)?
on May 21, 2007 at 11:48:40 pm

Thanks again for your detailed information and responses, Bob.

Yes, Tony, the best thing would be for me to have asked the festival in time what machines they are using, etc... But, the festival begins on Friday (MountainFilm in Telluride), and I had to FedEx them the tape today.

I did some more color correction yesterday, and then outputed to an UVW-1800 BetaSP deck taht I rented (at an IRE of 7.5), and sent it off.

I feel pretty confident that their setting specs were wrong.

For one thing, I sent them a priliminary BetaSP tape for them to test (before I sent the final), and I set the BetaSP audio tone to "0 db", and they said that the audio was o.k. (In their specs, they asked for audio tone at -20 db, so I am almost sure they are refering to digitial specs, and as Bob mentioned, probably a DigiBeta deck.

I appreciate everyone's thoughts and feedback.

Khashyar


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