VV can make illegal video.

farss wrote on 10/14/2003, 6:36 PM
No, no this isn't about breaking DCRM!

I've had a number of minor annoyance and posted a few of them but they were just annoyances and as no one else seemed to think them significant I haven't pushed them.

But just now they have all come together and I believe I have the answer but I'd sure appreciate some input from a few experts as this is a significant issue.

In a nutshell it seems all to easy to end up with levels outside the broadcast legal range. For example the Generated Media black will give a black level below 0 IRE when converted to analogue. This is a real no no as far as I know. If the black level falls below 0 then sync circuits may see this as a sync pulse and have a real dummy spit.

I've been having this happen a lot. I have a cheap but new TV that I use as a monitor. I output from VV through my D8 camera to the monitor and to record to VHS. I put 30 secs of black at the start of the time line, if there's a cut straight to a bright scene when that goes to the monitor, total sync loss. If I PTT with VVs black leader before the black on the TL, total sync loss at that point also.

Run the Broadcast Legal filter on the video bus and all these problems disappear. Look at the historgram after the filter and the blacks have been pulled up from zero.

So OK I've solved my problem why am i posting this. Well firstly to see if anyone else thinks I've really found the correct answer. Secondly because and I've said this before. Send a tape out for broadcast with levels below zero or too high and if the broadcaster cares about what they put to air they're going to reject it and that's a real bummer.

This isn't an issue for DV as far as I can see, it doesn't have sync pulses per se and as far as I can see should run from 0 to 255 in each channel else its just wasting resolution. However a tape that's going out for broadcast or being printed to an analogue format would seem to need to be legalised.

I'd always assumed I could blindly ignore all this technical stuff, the gear should convert the zero black level of DV to a legal black level when it's converted to composite video. I seem to have been a little too ignorant on this point. I kind of hope I'm wrong else it's just one more thing to worry about.

By the way I'm working in PAL, NTSC with +7.5 setup maybe a different story.

Comments

GaryKleiner wrote on 10/14/2003, 6:55 PM
Good point.

The default black is below 0 IRE, and should be set to R,G,B 16 to hit 0.

Same is true with the default white being too high at R,G,B 255, and should be set to 235 to hit 100 IRE.
Gary
farss wrote on 10/14/2003, 7:11 PM
Gary,
thanks. So I haven't lost my marbles.

I knew about the white levels and always set them back just to stop the getting crappy edges but I hadn't thought about the black level issue.

This really is something we need to take a LOT more care over.

I have a good friend who works in broadcast and they are forever rejecting programs because of illegal levels. Anyone with aspirations to get there stuff to air (read get money for it) really needs to give this some attention.
TheHappyFriar wrote on 10/14/2003, 7:44 PM
You've gotta remember that Vegas isn't just for making broadcast stuff. Film and computers don't have the same limitations as TV (16-235 levels). Infact, you'll notice that VHS can EASLY product illegal levels (I've make a pre-set in the color corrector to fix this).

If you viewed a R-16 B-16 G-16 "black" on a computer it would show a slight gray, not black. Then they couldn't call the preset black.

I've ended up making pre-sets for some of the things I plan to show on TV (like color corrector, solid colors, etc.) Infact, I've transfered stuff straight from Vegas to DVCPro and to an Adtec Duet mpeg-2 player (mpeg-2), and have never had a level problem with black (white on the other hand... :) )

the first thing I learned in College in my lightwave 3d class was that you NEVER make your colors go above 235. It will "look" like 255 on Tv. I guess it's just second nature to me now and don't even notice it. :)

Actuatly, the best thing I learned in college was this:
People don't care how it's done as long as it's done good.
StormMarc wrote on 10/14/2003, 8:13 PM
Yes this issue suprised me as well. I was bringing my renders into Premiere/Storm and the Canopus waveform was showing illegal blacks. Now I just make sure I always use a black media file (16,16,16,) on the track below when fading to black or running black. A Sony engineer commented in past thread and it sounded like they may address this in a future release. After all if we're using a DV project it should be at 0. If we want full 0-255 levels there could be a computer preset.

Premiere 6.5 background black is 0 IRE and the new PPRo is also but the PPro waveform artificially adds 7.5 set-up assuming that your DV deck is doing it on the analog output. (talk about confusing!) At least in Vegas we have scopes that don't lie.

Marc
farss wrote on 10/14/2003, 8:20 PM
I couldn't agree more with your last comment!

What is the difference though between your approach and simply ignoring the issue and then putting a Broadcast Color filter on the video bus?

I should run some tests on this myself, I'm hoping that the filter doesn't further compress stuff that is already legal.

I'm trying to get hold of a proper waveform monitor or vectorscope so I can see what I'm actually recording to tape after it's been through the A/D converters.
StormMarc wrote on 10/14/2003, 8:50 PM
To be honest I don't know except do you have to render everything when using the video bus or does it just render the illegal clips? With the black media method I know for sure only the shots that need it get rendered.

Another tip for those that want to keep your video legal is to run the levels filter in photoshop on still images before bringing them into Vegas. Set the output levels to 16 and 235 and that will give you 0-100 IRE levels. I just run the batch command when using lots of stills.

Marc
farss wrote on 10/14/2003, 9:43 PM
From what I can tell everything gets rendered so that is a downside.

Mostly though I'm working with lots of footage out of the telecine and I just put titles in between the reels so the viewer knows what they're watching.

Problem is the old film has the odd clear frame and the camera in the telecine sets the blacks and the whites at very high levels, prabably its AGC is too slow to cope. Going through it all frame by frame would be impossible, at least for the money the client will pay so just dropping the flter onto the bus seems to fix it up just fine.
StormMarc wrote on 10/15/2003, 2:39 AM
Thanks for the tip by the way... I'm still learning Vegas and the master bus is a great feature. So many cool things about Vegas still waiting to be discovered.

Marc
VIDEOGRAM wrote on 10/15/2003, 7:33 AM
Hi,

I've brought this issue to discussion on this forum a while ago. I produce TV commercials, render them in 1 file and bring them into another editing system hooked up to PREMIERE, an external waveform and a BETACAM deck for distribution.

While the scopes in V4 display accurate levels, the final render is different. A (16,16,16 RGB graphic) reads 7,5 IRE in V4 scope, as expected, but 0 IRE when brought into system 2. The file, when inported into the second system into Premiere, shows 0 IRE black.

Figures???

My turn around: I've found that applying the filter "color corrector/computer RGB to studio RGB" at the output of V4 before rendering makes the exported file legal for the second system. But rendering times are up.
It seams "weard". Logic tells me that I shouldn't have to do this, but tests have proven me that this step is necessary.
I've heard that MC's codec is a "scalable codec". Is it possible that it brings back blacks and whites to 0 and 110 IRE?

Gilles
stormstereo wrote on 10/15/2003, 8:26 AM
Ok Sony (or anyone who really knows). Which is the best way to make sure all illegal events are made legal for broadcast WITHOUT affecting the already legal events? Drop some FX (with what settings?) on the master video bus or do you have a better way?
Best/Tommy
SonyEPM wrote on 10/15/2003, 10:40 AM
Since Vegas can output video for web, stills, Pal, NTSC, NTSC-J, DVD etc, there is no one right level set for all output fomats.

In the case of DV for TV:

If you apply the broadcast colors filter with the desired preset to the entire project (just click the video output fx button above the video preview window and add it there) you'll be set. Yes, the entire project needs to be rendered, but there's zero thinking required.

You can also use the scopes to check the entire timeline, and apply the broadcast colors filter only where needed.

Project black level isn't setable in some secret pref, but if you create an empty track at the bottom of all the other video tracks, add the broadcast colors filter to that track, you can raise the blacks to 7.5 (or whatever you need).

DV/DVcam for air in North America (NTSC): If you use the "Conservative- 7.5 setup" preset, you'll probably never get rejected by any station, unless they INSIST that nothing ever peaks past a composite level of 100. In that case use "Extremely conservative- 7.5 setup". PBS national aired a Vegas-edited show awhile back, the "Conservative- 7.5 setup" preset was used to create the DVCam master. If you pass the PBS redbook test you'll pass any test.

If you render in Vegas and print back to tape with another app's DV codec (remember, DV codecs DECODE as well as encode), you may wind up with different results than you would have printing from Vegas. Watch out for that. Similarly, the hardware can make a difference- some DV decks or D>A converters may be adding setup a second time for no good reason for instance.
aboukirev wrote on 10/15/2003, 11:56 AM
At least Vegas users have a choice. Premiere Pro forcefully legalizes video for broadcast in every transition (due to YUV->RGB->YUV conversion) except cross dissolve (the only native YUV transition) - ugly.

In Vegas, secondary Color Correcton has Limit luminance checkbox and sliders for levels and smoothness - that will work to legalize video too.

Alexei
stormstereo wrote on 10/15/2003, 12:02 PM
Good one EPM. Thanks.
/Tommy
StormMarc wrote on 10/15/2003, 12:20 PM
Videogram said:

"While the scopes in V4 display accurate levels, the final render is different. A (16,16,16 RGB graphic) reads 7,5 IRE in V4 scope, as expected, but 0 IRE when brought into system 2. The file, when inported into the second system into Premiere, shows 0 IRE black."

I think the problem you are experiencing is due to your scope setting. 16,16,16, should actually read 0 IRE in DV editors. My understanding is that the 7.5 IRE set-up switch is for those that have set-up coming out of their 1394 to analog transcoder and want the scopes to reflect that. My DV deck (sony) does not add set-up on the analog out. If you click on the scope settings button in Vegas (next to the update scopes button) and choose studio RGB (16-235) and uncheck 7.5 set-up vegas will show the 16,16,16, at 0 IRE which is correct. ANYONE please correct me if I am wrong but my reading up on this confusing subject and actual experience has convinced me of the above.

I just tested this back and forth in Premiere 6.5 using the Canopus waveform and a 16,16,16, graphic (with the above settings) showed up as 0 IRE in both programs. I made a color matte in both Premiere and Vegas at 16,16,16, with the same results. (One odd note is when I exported a frame from Premeire with nothing on the timeline it showed up in Vegas as both OIRE and -7.5... very weird)

NOTE: The new PPro waveform always shows 0 IRE as 7.5 by default and does not let you change that. There is a thread here with people complaining about it http://www.adobeforums.com/cgi-bin/webx?13@201.6r5Tb4i4u8C.4@.2ccd2533/38

Marc
VIDEOGRAM wrote on 10/15/2003, 1:56 PM
StormMarc,

From what I've learned, a 16,16,16 RGB should read as 7.5 IRE. A 0,0,0 RGB should read as 0 IRE.
A 235,235,235 RGB = 100 IRE and a 255,255,255 RGB = 110 IRE. WEhen I check with an external waveform monitor, this prooves right. I've had the same discussion on other forums.
Maybe John Cline could elaborate ...

Gilles
altphase wrote on 10/15/2003, 2:56 PM
Aside from all the other issues involved here (proper setup levels, etc..) everyone has ignored your main problem, which is the video monitor loosing sync during dark to bright transitions. This probably has nothing to do with your levels but with the quality of your TV set or monitor. Many consumer grade monitors can't handle the transients from black to white and in extreme cases (as in going from 0 IRE black to full white) will loose sync during the transition. I've seen this many times on a cheap monitor, but never on a broadcast grade one. I actually has this problem with a number of Panasonic Pro Line monitors, but have not seen it since switching to a JVC BM-H1310 unit.

Dominik
TimTyler wrote on 11/19/2003, 12:57 AM
> In the case of DV for TV:

> If you apply the broadcast colors filter with the desired
> preset to the entire project... you'll be set.

What about in the case of DV to DVD using MC's encoder?
farss wrote on 11/19/2003, 1:04 AM
You can in general afford to be a bit more relaxed when it comes to DVDs as they're unlikley to be played directly to air.

Nonetheless you may find players outputing video that could upset TVs.

As far as I can see the MC encoder will encode the same levels as would have gone into DV. To keep it all legal then you need to exercise the same caution as SonyEPM was saying.
SonyEPM wrote on 11/19/2003, 8:50 AM
farss is correct- you don't typically need to use broadcast colors when delivering on DVD. If the colors are WAY hot, you could in theory run into some problem (chroma "ringing" perhaps?) but I've yet to see a problem like that in a DVD. For DVD, just make it look good.
BillyBoy wrote on 11/19/2003, 9:53 AM
I think that's some of the best non technical advice a Sony tech ever gave in the forum. Namely, "...just make it look good".

For example I know you probably should when viewing scopes keep the peak luminance of the waveform below 100, but sometimes I cheat and a spike here and there gets to maybe 105 or so. Why? It looks good. <wink>
RichMacDonald wrote on 11/19/2003, 10:00 AM
>If the colors are WAY hot, you could in theory run into some problem (chroma "ringing" perhaps?) but I've yet to see a problem like that in a DVD. For DVD, just make it look good.

Funny how certain explanations trigger additional questions :-)

But its not the DVD that matters, its the TV its played on. Surely?

I've got an old POC TV that buzzes every time a commercial comes on with a white background.
TheHappyFriar wrote on 11/19/2003, 11:20 AM
It's both the TV and the source. My old TV would buzz like crazy every time somethign white would be on the screen. My new one (new meaning new to me. It's an old NEC color monitor) works great. Also, if you make your colors legal for a TV show, the station/cable opperator could STILL boost them, making then illegal.

I'd say if a color is REALLY illegal it would blead. Bad. :) I've seen that happen before!
RichMacDonald wrote on 11/19/2003, 11:33 AM
>It's both the TV and the source.

Right. Meaning that I question farss and SonicEPM saying that "you don't typically need to use broadcast colors when delivering on DVD." If I've got a crappy TV, then I *do* need to keep my colors legal.
BillyBoy wrote on 11/19/2003, 2:04 PM
This is starting to sound like the which came first, the chicken or the egg in that famous never ending debate. OF COURSE if you using a crappy or badly calibrated television or if some cable company messes with things all bets off relative to how the video will look when viewed on a television.

My take is some obsess over "legal" broadcast values, messing with broadcast filters, etc., while overlooking the more basic things that CAN really matter like not botheing to adjust levels or skipping color correction and so on which is important in the context of how does it look as opposed to if it is or isn't legimate from a over saturated viewpoint or things like that since I know the vast majority here have no realastic chance or even a desire for their work to ever be "broadcast" where such things can matter.