Video Levels: 100 or 109%

[Craig Kovatch]

I'm shooting on an EX1R which has the capability of capturing video levels up to 109%, and I'm wondering if Vegas Pro will allow all of this through, or whether it clips everything at 100%. I haven't seen anything to make me think otherwise, I was just curious just in case I'm missing something.

Thanks.

Craig

[Marco Ba]

Vegas Pro let you use 109% which is RGB 255.

[Gene Gajewski]

Vegas won't clip the levels, but a video with those levels might be clipped by a playback device. The extra headroom is great so you don't lose highlights, but I'd suggest adjusting to proper levels when rendering from Vegas.

[David Jimerson]

That's probably not 109%, but 109 IRE.

Anything that hot is probably going to clip, and buzz on an NTSC TV set.

You'll see it in the waveform on Vegas. If it's above 100, it's probably trouble. You'll have blowouts.

It doesn't matter for tiny things like very hot highlight reflections in something like a car bumper, but it's surely not something you want to see in a white shirt.

[Craig Kovatch]

I've been adjusting the gamma and curves to keep everything under 100. However, I sometimes get whites that appear to lose detail around 80-90 IRE. I shot some test footage with zebra coverage at 70 and 75, and when I try to do grading, I have very little headroom before whites appear to start clipping. I realize we're supposed to trust the waveform, but visually, it looks like i'm losing details in the whites.

[Gene Gajewski]

You shouldn't be losing any detail. What *will* hose things up depends on the display you are using and how it's setup. NTSC 16-235 looks pretty washed up on a PC monitor. For PC monitors, it's best to use a secondary monitor that's been calibrated to sRGB. The 16-235 checkbox should checked to indicate that 16-235 should be expanded to 0-255. You shouldn't have to adjust gamma, but some tweak it to taste.

[Craig Kovatch]

I'm using a Panasonic TH-42BT300U plamsa display for grading. Are you saying I should have the sRGB box checked in the preivew device properties? I tried this and it made the image darker. When I would burn a Blu-ray disc, the footage on the disc looked lighter. I think the problem i'm having is the whole 16-235 vs. 0-255 thing. I'm editing on an LCD monitor buy my preview device is the Panasonic plasma. I'm running an HDMI cable from my video card (nVidia GTX460) to the Panny. I figured what ever I see on my preview display is what I should be seeing on Blu-ray. Setting the preview display to sRGB didn't do this.

[Gene Gajewski]

OK, now that I've got your display setup...

You're using an HDMI interface - that's designed to use video levels directly (16-235) so in this case do not check the 16-235 checkbox. You don't need to check sRGB either.

I'm not sure why the rendered output appears lighter - you've got me there. You might want to load a short clip of the rendered output into vegas and view it on the scopes - the output should be in the 16-235 range

What's crucial here is the pixel format settings in your project properties. Although the EX1 is letting you overshoot, it's still based on 16-235 video levels and gamma. It's important that the pixel format be either 8-bit or 32bit (video levels) and *not* 32bit (full range). That last selection will throw the levels off and the gamma too - which will cause problems with the image.

[Ray Turcotte]

Hi Gene could you clarify the following for me (and others)

When exactly should 8bit, 32bit (video levels) and 32bit (full range) project settings be used?

I ask this due to a recent observation I had with footage I shot with my AX2000. Normally, I set my project rendering to 32bit (video levels). On my last project I decided to switch to 32bit full range and suddenly my AX2000 footage looked awesome in vegas. The source video was vibrant!. Under 8 bit or 32bit video levels the the same source video is looked washed out.

Now where I get confused is when a project is only for web/PC playback using file based hd codecs. Seems to me if a project is not destined for DVD playback, then we need rethink the vegas work flow and bypass the studio video levels presets altogether.

[on edit] Where i think the main confusion is there seems to be 3 types of projects that have competing work flow requirements:

1) Legacy DVD/NTSC/PALbroadcast playback
2) Computer/Web file based SD/HD playback
3) Blueray HD playback

Does this make sense?


Thanks

[Gene Gajewski]

Both 8 bit and 32 bit (video levels) maintain the proper 16-235 levels. 32 bit video levels has an advantage during compositing in that floating point allows smother gradations.

32 bit (full range) operates something a bit differently - some of it depends the the codec you're using. For MPEG-2, Vegas will expand levels 16-235 to 0 and 255. This results in a couple of things: values below 16 and above 235 are now clipped! Highlights are blown and darks are crushed. The effect may appear as increased contrast - as you have seen.


You can test this for yourself. Load up a clip in 8 bit or 332bit (video leves) mode, scopes set to 16-235. find a frame where the highlights go over 100 %. Uncheck 16-235 on the scopes. The highlights should be close to 100, but not over. Now switch the project to 32 bit (full range). Highlight are now clipped.

[Ray Turcotte]

Thanks Gene, what you say makes sense...but

I just did a video shoot this weekend where I am mixing footage from a "borrowed" Cannon M400, a sony CX550v and my ax2000.

The cannon [and I will claim that all consumer level camcorders and HDSLRs] most definitely recorded in the 0-255 range. I confirmed this looking at the vegas video scopes and placing the raw footage on the time line. The ax2000 on the other hand shoots in the 16-255 range (as i normally set exposure with my zebras at 95% I'm not worried about blown highlights on the ax2000. - the 550 was in between - grrrr)

ALL of the camera footage looks stunning on the time line if the the project is set as a 32 bit project. If I switch to a 32 bit (video levels) project , the blacks are shifted up from 0 into to 32-64 range, which wipes out all contrast an in my opinion, making a mess of the video.

Since this project is only destined for computer playback and youtube/vimeo, I do not understand why it is important to force it into the 16-235 (studio) space as you suggest.

Where this issue is confusing to me is what steps need to be taken n vegas when the following applies:

1) the camcorder shoots in studio rgb or

2) the camcorder shoots in computer rgb;

and the choice of final delivery method, as

3) some codecs are computer rgb

and

4) some are studio rgb, as you pointed out.

Thanks

[Ray Turcotte]

Thanks Gene, what you say makes sense...but

I just did a video shoot this weekend where I am mixing footage from a "borrowed" Cannon M400, a sony CX550v and my ax2000.

The cannon [and I will claim that all consumer level camcorders and HDSLRs] most definitely recorded in the 0-255 range. I confirmed this looking at the vegas video scopes and placing the raw footage on the time line. The ax2000 on the other hand shoots in the 16-255 range (as i normally set exposure with my zebras at 95% I'm not worried about blown highlights on the ax2000. (the 550 was in between - grrrr)

ALL of the camera footage looks stunning on the time line if the the project is set as a 32 bit project. If I switch to a 32 bit (video levels) project , the blacks are shifted up from 0 into to 32-64 range, which wipes out all contrast an in my opinion, making a mess of the video.

Since this project is only destined for computer playback and youtube/vimeo, I do not understand why it is important to force it into the 16-235 (studio) space as you suggest.

Where this whole issue is confusing to me is what steps in vegas need to be taken when the following applies:

1) the camcorder shoots in studio or computer rgb color space;

and

2) the choice of final delivery codec container, as some the codecs are studio rgb and some are computer rgb, as you pointed out.

Thanks

[Jon Shohet]

Ray, if you haven't already, you might want to read the following :
Color spaces and levels in Sony Vegas 9 and 10
YouTube Levels Fix
I think they should more or less cover all your questions.

Also, don't confuse cameras that shoot full-range levels (like the Canon DSLRs) and cameras that shoot video levels with "super whites" (many HD camcorders do this).
The former will usually need a computerRGB -> studioRGB change. The latter do NOT usually require any studioRGB -> computerRGB change.
Probably the only time you would want to change everything into computerRGB is if you are exporting to an RGB format like Lagarith, unless it's just for preview purposes.
Even then, you would usually want to do that using the "studio RGB to computer RGB" levels FX in 8-bit or 32-bit (video) and NOT by switching to the 32-bit (full-range) mode, unless you specifically want to work in a linear gamma compositing mode and you know what you are doing.

[Ray Turcotte]

Thanks Jon for the outstanding answer and links. I'm going to study them thoughly

[Ray Turcotte]

Joh

I've read through the articles and will now use the following rules when mixing footage in vegas:

1) Start a new project as 32 bit (video level). (Or 8bit but I prefer 32bit)

2) Collect all media files into the project bin and inspect them to see if they are studio or computer RGB. For media that are computer RGB apply the computer to studio video levels preset directly on the media. For studio RGB media leave as is except I may choose to correct super whites.

3) Apply the studio to computer levels preset on the video output player as the final effect in the output chain.

4) Edit the project as I wish, understanding its a studio RGB project on the time line and that I'm watching computer RGB in the preview player (I don't have a separate HDMI
monitor)

5) The project will render to any computer RGB delivery container as is with no further changes.

6) Bypass or delete the studio to computer levels preset in the preview player to render to studio RGB delivery containers or for nested veg files or for intermediate loseless renders that are reimported back into the timeline

This now makes perfect sense to me. All that is missing is a complete list of codecs and what RGB they use. It is easy to figure out what colour space any camera records in by inspecting the blacks levels.

Thanks, very much, I now understand and have a simple method that can render to anything.

Ray