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Old February 12th, 2004, 11:53 PM   #46
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i have made a few TEST making a VCD.
which may or may not explain if you need to set DVD player to set up or to 0 blacks?

using vegas codec to create the mpeg 1 VCD . the black level is correct with DVD player to add black set up..

using the microsoft DV codec to create the mpeg 1 VCD. the black levek looks correct with DVD black level at it's default ( no set up).

the DV codec's are only used to decompress the avi files then the mpeg1 codec compresses them to mpeg 1 BUT it appears that just the uncompressing sets up the black levels ??

dropping both clips into Vegas TL the mpeg created using msDV codec has the blacker black .. using the waveform 0-255 scale the msdv mpeg has a 0ire black .. the vegas mpeg has 6 ire black .. changing scale to 16-235 the msDv mpeg has a -7 ire black .. the vegas mpeg -1 black.

my guess is that the same might be true when creating a mpeg2 for DVD ... which might result in a mpeg 2 using Vegas codec to decompress might set the black level so you need set up on the DVD palyer ? .. using the msDV codec in Vegas might set the black levels that the DVD player needs to be set to 0 black level .
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Old February 13th, 2004, 03:24 AM   #47
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Went to the Adam Wilt article dealing with this, and read:

Some DV and DVCAM camcorders like the AG-DVX100, DSR-PD150, DSR-250 can record a video signal with "7.5% setup." Is that OK?
The AG-DVX100, PD150 and DSR-250 have a "7.5% setup" setting in the menu. Don't use it! It does not add setup to the analog outputs; it modifies the digital data coming from the camera head by boosting the black level, resulting in washed-out blacks, reduced precision, and nonstandard tapes as described above. As a result the analog video played back from the camcorder or viewed live has its blacks at 7.5 IRE, so the signal looks like it has setup, but what it really has is a too-high black level!

He didn't mention the XL1s, but as it has an adjustable pedestal, that's essentially the same thing, no?

Am I to understand that unless the setup slider is ALL the way left, I'm shooting weird non-standard video, and also cheating myself out of an additional range of constrast?
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Old February 13th, 2004, 06:51 AM   #48
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I think that's completely true Josh.
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Old February 13th, 2004, 08:43 AM   #49
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You also need to remember that some codecs behave differently from others. Some assume that 7.5 has been added and will actually expand the color range for display. Others just leave everything alone. You will definitely get different result is you use the MSDV codec as compared to the Sony codec.

There's been a HUGE discussion here:

http://mediasoftware.sonypictures.co...47&Replies=101
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Old February 13th, 2004, 08:56 AM   #50
 
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Josh...

If I understand what Rob Lohman said earlier in this thread, the XL1s pedestal setting doesn't really affect the DV spec requirement of 0 IRE, all blacks will always be written to tape as 0 IRE. What the on cam pedestal slider does is affect the way the RGB color space is mapped to IRE signal. If the slider is all the way to the left, you will map pure black to 0 RGB. As you move the slider to the right, you will map pure black to higher RGB values. The DV spec is for pure black to be at 16 RGB. The slider allows you to set pure black at 0 RGB. This produces blacker blacks, but, it's also a non-standard setup for Lab color. I'm not sure of the implication of this, but,if you set the 16-235 Lab Color checkbox in Vegas 4, it will remap balcks to 16 RGB anyway.
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Old February 13th, 2004, 12:26 PM   #51
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So that broadcast color filter can undo something stupid I do during production? And I also won't be able to tell it's doing it?

On a different attack: What slider setting on the XL1s black pedestal maps pure black to 16,16,16? Can it go lower? Why--what's the point, that is? It's non-standard--what are you gonna be able to do with it at that point without correction?

I never asked this, and now I'd like to know: Does the black level setting on the XL1s affect the SEMPTE color bars it generates? Do the black levels on the bars change in correlation to how you move the slider?

I did a test, using Vegas' software waveform monitor. I recorded with the lenscap on, assuming (incorrectly?) that that would yield me an image of the camera's current "pure black." I recorded with the slider on the pedestal at it's factory setting, and then all the way down to -6 notches. I found that at two notches, it will register as 7.5 IRE, but only if the "studio RGB" box and the "7.5 Setup" box are checked. Otherwise, it reads at slightly below 0. Maybe I did something to completely invalidate the test.

On the camera's bars, are they the same as on the Video University tutorial, found here (http://www.videouniversity.com/tvbars2.htm) the one about monitor calibration, where it shows, from left to right, the three black bars being 3.5, 7.5, and 11.5 IRE? Or is that only from an analog source's bars?
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Old February 13th, 2004, 12:58 PM   #52
 
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<<So that broadcast color filter can undo something stupid I do during production?>>

well, if it's a luma problem, yes. if you blow out the high-lites, it's lost forever...no recovery...;o)

<<On a different attack: What slider setting on the XL1s black pedestal maps pure black to 16,16,16?>>

I think the neutral (zero) setting is RGB16, but, I'm not sure.

<<Does the black level setting on the XL1s affect the SEMPTE color bars it generates???

no!

<<I found that at two notches, it will register as 7.5 IRE, but only if the "studio RGB" box and the "7.5 Setup" box are checked. Otherwise, it reads at slightly below 0. Maybe I did something to completely invalidate the test.>>

yes, you did. checking those boxes will remap the recorded data to NTSC601 standard. If you check those boxes, it doesn't matter what you set the XL1s slider to.


<<On the camera's bars, are they the same as on the Video University tutorial>>


They should be, but beware....there's a LOT of incorrect color bars available on the internet. The only way to be sure is to open a frame in Photoshop and use the sample eyedropper to read the color values of those bars. Also, there's a free tool available that will tell you the RGB values of anything on the screen. It's called "WHATCOLOR". Do a web search for a download site.
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Old February 13th, 2004, 01:41 PM   #53
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Ok. . .so the neutral setting on the slider is the equivalent of mapping pure black to RGB 16 16 16--does that mean that any other setting for the slider will be unbroadcastable unless corrected? I don't want to be on Adam Wilt's "non-standard island off in my own world." As I said, I find, at least when looking at my monitor, -2 on the blacks to be somehow more pleasing.

And wait--if I'm ALWAYS recording black at 0 IRE, then if plug my camera into a hardware waveform monitor and change the pedestal, that black should always stay at 0 IRE, right? Like if I just close the iris all the way and record? But you guys say the value will change, even on a waveform monitor, so how can I always be recording at 0 IRE if it's not showing that I'm always recording at 0 IRE?


I imported the bars straight from the Xl1s, and did more tests. I found that when looking at Vegas' waveform monitor (the only thing I have to go by right now):

1) When the "studio RGB" box is checked, and the "7.5 Setup" box unchecked, the pluges read, from left to right: -4, 0, 4

2) When the "studio RGB" box is unchecked, and the "7.5 Setup" box unchecked, the pluges read, from left to right: 3, 6, 10

3) When the "studio RGB" box is checked, and the "7.5 Setup" box is checked, the pluges read, from left to right: -3, 7, 11

Using Vegas' own SEMPTE bars, the settings are relatively close, though seeming more accurate--only off by one IRE unit compared to the XL1s'.

Which is "right"? Which is good? Which is bad? Which is a true representation (or closest to true of what the camera's getting?)

The settings on the software waveform monitor don't actually change the video itself, just how the waveform monitor sees it, right?

I was under the impression, from one of the first posts Bill wrote, that the broadcast colors filter only worked if using a proc amp, or bringing in video with actual 7.5 setup. Did I read it wrong? If so, shouldn't I be able to see what the filter is actually doing just by applying it? I've tried it and see absolutely no difference. Does that just mean the video I'm applying it to has no black areas that are problematic?

Several of you guys mentioned you did tests with a waveform monitor that showed -2 on the slider to be 7.5 IRE. You used a regular hardware waveform monitor, or a software one from an NLE?

When will I "get it?"
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Old February 14th, 2004, 11:09 AM   #54
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vegas codec supports 601 mapping ( 16-235) so you should use that ... if you then add "set up" to 16-235 scale you will see your black level move up to 7 ire. however it did NOT change anything on your clip and has NO affect on rendering - the black level will remain at 16rgb.


also note that Vegas SMPTE bars the 3 rd pluge ( the one to right of middle ) reads different then most. it reads 41 rgb
i find most SMPTE bars ( from beta Sp camera's ) the same pluge is 26-28 rgb ... so be careful when you set up your monitor like the "Video University tutorial" and they state to barely see the pluge to right of middle ( 7.5 black = 16rgb) ...
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Old February 14th, 2004, 05:07 PM   #55
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I'm sorry, I still dont' get it. How can the black level move up to 7 IRE from a lower level, and not have it be visible?


As for setting the pluge, I usually set it not by judging the one on the right, but by judging the other two, that is, making them blend into one another, regardless how bright/dark the lightest bar is.
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Old February 15th, 2004, 02:15 PM   #56
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i don't quite understand it all either ..

i assume but don't know for FACT !!
the scales are for different mediums.
if i'm do a web based clip. those are viewed on computer monitors which use RGB mapping on a 0-255rgb scale.
so if you want black on a computer screen you should use the scopes 0-255 scale and set you blackest black at 0. a 255 rgb white will read 100 ire .. now if you were to use the 16-235 scale for this project 16 rgb now read 0 ire but on a computer monitor that is 0-255 that 16rgb is not going to be BLACK but then the 16-235 scale is not for web based mediums but for NTSC.

NTSC
so i assume that if i have a USA TV the black level is for 7.5. so i would use 16-235 scale with set up box checked .. now the scale shows me where luminance will fall on that TV that has 7.5 black level... on the scope black level is at 7 ire

if i have a monitor and lets me choose between 0 and 7.5 black level. i choose 0 - then i use the 16-235 scale only ( no set up) and now the scopes show me where luminance falls on that monitor. on the scope black level is at 0 ire.
so on these 2 ntsc the actually clip black level didn't physically change in the clip but lets you see how the intended tv/monitor will display the luminance ..
YES viewing it on a monitor that has a 0 or 7.5 black level will be slightly different. if you watch the scales between no set up and set up you will see the mid range move slightly . so a face that has 65ire (no set up) might be 70ire with set up ... so basically a TV with a 7.5 black level has to fit everything (16-235 rgb) in between 7.5 to 100 ire .. a monitor with a 0 black level fits it all (16-235 rgb ) in between 0-100 ire range . so you can see that the TV with 7.5 black has to fit the same 16-235 scale in it's shorter range (7-100 ire) ...
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Old February 15th, 2004, 02:48 PM   #57
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Ok, I think I sorta kinda maybe possibly perhaps get it. . .are you saying that these are assumptions, Don, all of what you just posted? Or fact?

You're saying on the Vegas waveform, check the boxes according to what medium you're AIMING TOWARD, not what medium you're IMPORTING FROM? So if I'm aiming toward NTSC devices, I want the 7.5 box checked, as well as the Studio RGB box? And if not, like you said, a computer monitor, then uncheck certain boxes. . .


The last paragraph still threw me a little.
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