16-235 Broadcast safe?

[Graeme Nattress]

16-235 is NOT NTSC video with setup. Digital video doesn't have, never will have setup. Setup is a none-issue with digital video.

Why 16-235? Well, digital video has to accurately digitise all analogue video, and analogue video can have super black information, and it can have illegal hot white information. Hence the head room and tail room for the legal are in digital video. Codes 0 and 255 are not used to represent anything, but 1-15 is for super black, 16 is where correct black for all video systems should be, and 235 for white, with 236-254 for super white.

DV Cameras shoot in the 16-254 range, as they often shoot well into the super white region.

Black is code 16 the world over, it's got nothing to do with setup.

Graeme

[Bill Ravens]

This is my understanding....that CCD's capture in 0-255, however, the DV spec is 16-235. Therefore, anything that is recorded into the DV standard is 16-235. There is no choice in the matter unless one shoots and records into another format than DV. The IRE standard (setup)applies only to NTSC, not DV.

[Graeme Nattress]

CCDs are analogue devices, and hence do not capture with any digital value. All the magic happens in the A to D converter and DSP. Also, it's not just Dv that uses 16-235, as that is the CCIR601 standard, ALL Digital formats use, or the 10bit equivalent which is 64-940 (out of the nominal 0-1023 range of digital codes available). So D1, DV, DVCPro, DVCpro50, Digital Betacam (10 bit), DV, HDCAM, HDV, DVD, D9, D5 etc. etc. etc. all use the above ranges.

7.5IRE setup only applies to North American NTSC analogue video. Other NTSC's around the world use 0IRE, as do all PAL formats. USA and Canada (don't know if any other countries use 7.5IRE) are basically an island when it comes to the bizarre issue of setup. Japan had the sense to ditch 7.5IRE setup back in 1985. I don't know wether the other NTSC countries ditched it as well, or perhaps never had it in the first place.

Graeme

[Sean McHenry]

We are once again bogged down in the terminology and not the heart of the issue which is, do I "add" setup if I have that little switch on my camera or not?

If I use the Add Setup on, specifically, a Sony DSR series camcorder, what is that really doing to my video? Not what do we think it is doing but what is that particular camera really doing to my levels?

Is is simply flagging the tape or deck so analog output is at the correct 7.5 IRE or is it artifically bumping the digital levels to 32 from 16 and thereby making the analog output too hot? Or, is it bumping the digital to 32 to make the analog 7.5? I have to go dig out the scopes and see just what it is doing I suppose.

So what would be the way to see what is reallly going on here? I think I would have to shoot a chart with both the "add setup" on and off. Look at the analog output for both setting on a standard waveform like a 528a for both recordings and see where black really falls. That will tell me the correct setting if I need to use analog output from the camera.

I would then have to import footage into the Avid as DV footage and select a frame from each recording and save it out as a targa or some other lossless format, open it in Photoshop and look at the recorded levels.

Here is my hope...I would hope if I don't select "add setup" that it would play back both digital and analog at 0 IRE. I also would hope if I select "add setup" the camera would only add setup to the analog output of the camera to make it 7.5 legal for NTSC, and not raise the digital to 32.

Now, to really check this I suppose I should repeat the same playback and capture with another actual deck, like the DSR-11 or 25. That would show if there was some unusual manipulation going on in the camera.

At least that then is my understanding of how it probably should work. Sound right?

Sean

[Sean McHenry]

On the Japanese thing, I remember we bought a 500 Digibeta deck some years ago that had the output fixed at 0 IRE for analog. We had to keep the thing in variable all the time to get 7.5 out of it.

I understand that for digital but it was fixed to 0 for analog too. That was back around 1998 or 1999 as I recall.

Sean

[Bill Ravens]

Graeme...thanx for the clarification. I didn't realize RGB16-235 was for all of CCIR601.

Sean...Adam Wilt, who I consider quite qualified, says on his website not to use setup on any DV camera. If you read his logic, it's quite sound. According to Adam, many cam makers erroneously apply setup(via a user selectable switch) to the DV recorded signal. Perhaps they've gotten smarter in recent years and fixed this error. If you have access to DVRack, it would be a simple matter to connect your DV camera and study the waveform monitor as you switch SETUP on and off. I've satisfied myself with my XL2, that dialing the setup slider does, indeed, change the black level only, above and below 7.5 IRE. For shooting to digital output(e.g. for the web) I'm losing overall bandwidth in the blacks, by setting my setup above 0. For ultimate conversion to DVD (US NTSC), setting my IRE above 0 results in muddy looking blacks on my own system(JVC settop player outputting to a Sony 32" WEGA).

[Graeme Nattress]

Your Sony camcorder, if you set it to add setup produces a DV tape which uses the 32-235 range for video, which is not CCIR601 standard and will be incompatible with any NLE. Just imagine what happens on a dissolve when the NLE expects black to be at 16 but you've got it at 32 - your dissolve will no longer look right. The analogue outputs on the camera will have their black still at 0IRE (as they translate code 16 to 0IRE), but it will look like the black on the tape is at 7.5IRE but really it's grey that looks like 7.5IRE black, if you know what I mean.

Basicially, if you're in an all digital environment, never add setup in your camera. If, for a project you're hooking the s-video, say, output of your DV camera to a production switcher and you're switching against cameras that have their blacks at 7.5IRE for real, then, if you don't have a spare proc amp, flick that switch on the DV camera to make life easier for you, but any tape you record while it's flicked is non-standard and indeed, sub-standard on quality.

Sean, you can't talk about digital being at 0IRE. There is no IRE in digital. In digital we have to talk about black being at, say, code 16, which is correct for CCIR 601. Sorry to be pennickity, but to say that a digital signal is at an analogue level makes less than no sense at all, even though I know exactly what you mean.

Graeme

[Pete Wilie]

All I can say, after reading this long thread, is that you guys have confused the hell out of me!
I have just bought a PD170, and it has a menu item called "SETUP", with options of 0% or 7.5%.

Which should I select for making videos that will be distributed as DVDs in the U.S.?

[Graeme Nattress]

0% is the correct answer. That's for a number of reasons:

a) you're using an all digital workflow so setup doesn't apply anyway.

b) the PD170 doesn't add setup correctly. It burns it into the digital signal making the DV video have incompatible digital levels to fake North American legal analogue black levels.

Graeme

[Pete Wilie]

Thanks for the clarification Graeme.

Best Regards,
Pete