Whites crushed on render

[Sami Sanpakkila]

If I apply 32bit should I put levels FX on the video output with Comp to studioRGB conversion?

[Perrone Ford]

Originally Posted by Sami Sanpakkila

If I apply 32bit should I put levels FX on the video output with Comp to studioRGB conversion?

Comp to Studio levels do not work with 32 bit. And I have found them unnecessary. That would probably help you with this 8-bit issue though. You really ought to spend some time absorbing Glenn Chan's page. It covers the problem fairly thoroughly though it can be a bit tricky to follow.

[Peter Jefferson]

Clipping whites are not the only issue here. Image clarity/sharpness is also being affected. What res are you rendering to? What is your source res? What bitrates are you using within your render?

There are so many variables, that to say its this or that without knowing what the destination actually is (aside from mp4) is not going to solve the problem.
By the looks of how the whites have flushed out I'd say its a codec issue NOT a colour space issue.

[Sami Sanpakkila]

When I convert my project to 32 bit without any color space conversion the whites get crushed so there must be some kinda conversion I have to do?

[Sami Sanpakkila]

Here is an example:
In 8bit:
http://www.dvinfo.net/conf/attachmen...1&d=1203280538

After changing project to 32 bit:
http://www.dvinfo.net/conf/attachmen...2&d=1203280538

[Bill Ravens]

Perrone...

I've been around and around on this issue. No one seems to want to listen to what you're saying about Glenn Chan's page.They just continue to wonder why they're crushing the shadows or blowing out the hi-lites. It's hopeless.

[Sami Sanpakkila]

Bill, you must understand that for people who havent been around this stuff for decades its not peanuts to go to a page and go, oh thats it.

Im getting a lot of information and it's all very overwhelming. For someone who already knows this stuff it must be obvious. Ive read Glenns charts a hundred times. I've been studying this issue a lot. Its just not clear to me yet. That is why Im asking people like you for help.

Now I was adviced to change my project to 32bit and was told that I shouldnt do an RGB conversion. But now the whites are clipping.

Sorry if Im trying your patience but once I get this I will be able to help others with the problems and it wont be on your shoulders anymore.

Sami

[Bill Ravens]

Sami..

I agree. This is a very frustrating issue, even for myself. And Chan's white papers are also very confusing. So much so that I've abandoned Vegas. They've done their users a great disservice with version 8. The nearest I've been able to come to a conclusion is quite the contrary to what you've been told. I was told to stay in 8-bit. Sothere you have it...no one really knows. Some codecs will convert the output, regardless of what bit depth you start with.

[Sami Sanpakkila]

ok ok ok! So, I decided to ditch rendering to Mainconcept mp4. im now rendering with WMV and everything looks good. Im doing it from 8bit project.

Render looks good in Windows media player. Looks good upped to Vimeo and all these look like it looks in the Vegas preview window.

So thanks for your help. To recap my problem was that I was rendering with a codec that changes the RGB and creates problems.

Thanks again. And Bill, I just shot a music video today using your picture profile settings :) Ill put it in the EX1 footage section once I finish editing. I find your PP works like a miracle in a sunny weather outdoors.

Sami

[Bill Ravens]

yeah. I've had good luck with WMV and the Cineform codec, as I wrote above. rendering to the mainconcept codec is very problemmatic. This can be a real issue if you want to render to a DVD. I've been using TmpGenc or Procoder for my mpeg2/DVD renders; and, that seems to work very well.

[Randy Strome]

Hi Sami,

I think I may be able to offer a concise answer for you here as I have struggled with your exact problem, and it is very confusing.

Do this test:

Take a very short EX1 clip and add it to a Vegas timeline with your properties set to 8 bit, and with NO studio to Computer RGB conversion done. Then render it out to a file using Mainconcept settings here http://eugenia.gnomefiles.org/2007/1...-for-vimeo-hd/.

Next, change the settings to 32 bit (or do a Studio to Computer RGB conversion). Render the same clip using the same settings.

If your results mirror mine, the end files will look the same.

What this essentially tells you is that Mainconcept render is essentially doing a studio to Computer RGB conversion only on files that have not already been converted. So, if you have already brought up your whites in Vegas, this will blow them through the roof.

I hope that helps!

[Glenn Chan]

Now I was adviced to change my project to 32bit and was told that I shouldnt do an RGB conversion. But now the whites are clipping.

Ok, step-by-step, here is what I would do.

1- Drop your clips into a 8-bit timeline. (The instructions below won't work for 32-bit.)

2- (Optional) Map the superwhites into legal range.
Add Levels filter
output start = 0.006
output end = 0.920

3-
If rendering to the main concept MPEG2 or MPEG4 encoder:
Do nothing for step 3.

If rendering to WMV (the normal way via file-> render as, not WME):
Apply a second Levels filter. Use the "studio RGB to computer RGB" preset.

4- View those files outside of Vegas. e.g. View any WMV files in Windows Media Player.

------------

Here is what's happening:
A- Most cameras, the EX1 included, will record illegal values which are also referred to as "superwhites". These are values that are above white level and usually will end up clipped. For these values to get clipped is normal.
It's arguably a bad way of designing cameras.

In any case, you can map the superwhites into legal range to avoid this. This is what step 2 does.

B- In Vegas, you need to manually wrangle your color space conversions sometimes. (Arguably, this is bad design / not easy to use especially since you need to know what conversion you need to perform.)

In any case, this is what step 3 does.

C- Vegas 32-bit mode adds two additional layers of complexity (compositing gamma, and codecs behaving differently)... we avoid this in step 1 by going with a 8-bit project.

D- Vegas previews and scopes may not be accurate/appropriate. This is what step 4 addresses.

[Glenn Chan]

Originally Posted by Randy Strome

Do this test:

If you:
A- Start a 32-bit Vegas project.
B- Render from there to a MPEG4 (or MPEG2) format using the main concept encoder.
C- Bring that clip into a 8-bit Vegas project, or change the Vegas project to 8-bit.

You'll see the clipping that the original poster is seeing. This happens because the superwhites are getting clipped off (superwhites are the values above legal maximum white).

[Glenn Chan]

Regarding the comments about my article being confusing:

1- I'd be interested if there was a simpler way of explaining this stuff.

2- It's kind of complicated because you have to pay attention or be aware of at least six/seven different things (maybe more):
A- The video preview may not be correct.
B- The scopes may not be correct.
C- The behaviour of the codecs of all your source material. studio or computer RGB
D- The behaviour of the codec you're rendering to.
E- That the behaviour of some codecs changes depending on 8-bit or 32-bit mode.
F- Compositing gamma (affects whether the studio<-->computer RGB conversion presets do what they say)
G- Cameras record superwhites / illegal values above white.

On top of that, hopefully your monitoring is correct (and there's a number of potential screw ups there).

Would it make more sense if I pointed out those seven things upfront??

3- The goal of my article was that you could figure out the right steps for any situation, not just particular situations.

The instructions in my first post of this thread only covers a particular situation and doesn't apply to other cases. There are many different ways of getting the color wrong- that includes Cineform (e.g. render from Cineform to MPEG2; you'll see different results in a 8-bit versus 32-bit Vegas project). So you need a way of figuring out how to get the right levels in any situation.

[Sami Sanpakkila]

Originally Posted by Glenn Chan

2- (Optional) Map the superwhites into legal range.
Add Levels filter
output start = 0.006
output end = 0.920

Thank you very very much Glenn for the detailed advice.

I took the MXF file to Vegas 8bit timeline.
I added levels effect and added Comp RGB to Studio RGB.
(Whites look gray on Vegas preview window)
Rendered as mainconcept MPEG4.
(Whites look as they should be!)

So in essense what Im seeing in Vegas preview window is NOT what comes out after render to Mainconcept.

So wow! Im getting good results now with MPEG4, excellent!

One question though, why did you point out step 2 is optional? If I dont do the RGB conversion the whites dont look proper after render. So in essence I must do it dont I?

So the way to work with this is to do do the RGB conversion just before render. This way you see what you get in the preview window.