Black crush/loss of brightness after final encoding

Musicvid wrote on 12/11/2018, 5:46 PM

This is called "leveling," and because of colorspace and camera levels, is something you must do every time before encoding.

It's FAQ #24, and I suggest reading all the FAQ.

https://www.vegascreativesoftware.info/us/forum/vegas-pro-faqs-and-troubleshooting-guides--104787/

espen-braathen wrote on 12/12/2018, 2:01 AM

My god. This has effectively trashed all my edits in the latest 3-4 years!

While I have a good understanding of various codecs, color spaces and the difference between the 16-235 of a full 0-255 signal, the solution to correct for this does not actually present itself in the FAQ IMO!

And should not VEGAS do this automatically? Basically all 8 bit video uses 16-235 range!

Is there a video tutorial to show how its done manually?

NickHope wrote on 12/12/2018, 2:31 AM

Read these comments, and preferably also the rest of the thread that they are in:

I felt it was beyond the scope of the FAQs to provide a full color-correcting/grading tutorial (or maybe I was a bit lazy; it's a big subject).

NickHope wrote on 12/12/2018, 2:34 AM

Also, as background, see this old survey: https://www.vegascreativesoftware.info/us/forum/survey-what-min-max-levels-does-your-cam-shoot--84677/ You will almost certainly have to treat footage from your various cameras differently to get a uniform result.

espen-braathen wrote on 12/12/2018, 2:49 AM

I must manually add "Levels Video Track FX" to every single video track on the timeline?

To me it sounds logical to select "Studio RGB to computer RGB" (Since 16-235 (video) to 0-255) but this makes the image even darker.

"Computer RGB to Studio RGB" is the only option which seems to actually brighten the image.

espen-braathen wrote on 12/12/2018, 2:55 AM

At the time being I have no interest in either color correction or camera matching.

All I want to do is to mach the brightness/contrast of the final edit to the source file.

NickHope wrote on 12/12/2018, 2:57 AM

I must manually add "Levels Video Track FX" to every single video track on the timeline?...

Or to the individual events, or to the whole project, depending on the consistency of the levels that your project's footage has.

You can also use one of the other FX such as Color Curves, but the Levels FX is one of the more straightforward.

...To me it sounds logical to select "Studio RGB to computer RGB" (Since 16-235 (video) to 0-255) but this makes the image even darker.

"Computer RGB to Studio RGB" is the only option which seems to actually brighten the image.

It's rare for a stock FX preset to be exactly what you need, especially with cameras like yours where the default luminance range and the exposure can be adjusted. You need to understand what levels your footage has and what correction is required. You really need to use and understand the video scopes if you want to get it right. There are no real shortcuts to this.

espen-braathen wrote on 12/12/2018, 4:13 AM

It's rare for a stock FX preset to be exactly what you need, especially with cameras like yours where the default luminance range and the exposure can be adjusted. You need to understand what levels your footage has and what correction is required. You really need to use and understand the video scopes if you want to get it right. There are no real shortcuts to this.

Well, the standard is 16-235 so this is what Vegas should excpect and correct regardless of what actuall camera manufacturers put into their products.

As it's mostly GoPro footage these days there is no selecable settings here.

BTW: Why is the preview window contrast correct and the encoding "contrast" not if I do nothing? (I.e. the contrast in the preview window has always looked normal, only the final encode contrast has been wrong.)

Also after applying the "Computer RGB to Studio RGB" levels correction the encode looks more normal, but now the preview video is overly contrasted/bright. Different levels settings for the preview?

NickHope wrote on 12/12/2018, 5:05 AM

Well, the standard is 16-235 so this is what Vegas should excpect and correct regardless of what actuall camera manufacturers put into their products.

In general it does.

As it's mostly GoPro footage these days there is no selecable settings here.

I think you can still affect stuff like that if you get into Protune?

...Why is the preview window contrast correct and the encoding "contrast" not if I do nothing? (I.e. the contrast in the preview window has always looked normal, only the final encode contrast has been wrong.)

The preview window contrast is "correct" if your camera shoots nominally 0-255, which is what GoPros do, and what Panasonic GH cameras can do if set that way. To answer why the 2nd part, I'd have to refer you to someone with more expertise than me: http://www.glennchan.info/articles/vegas/v8color/vegas-9-levels.htm In practical terms, for 8-bit, it just does.

Also after applying the "Computer RGB to Studio RGB" levels correction the encode looks more normal, but now the preview video is overly contrasted/bright. Different levels settings for the preview?

That preset should make the preview less contrasted, not more. But the typical impression is that it is overall a bit brighter and washed out.

In general, the preview window is not WYSIWYG for final playback outside Vegas. My preferred way to achieve that would be the SeMW extension.

Finally, I can't emphasize enough how important the scopes are in getting this properly right. Without them you're guessing really.

Give those 2 links another careful read. The answers and suggested methods are in there.

espen-braathen wrote on 12/12/2018, 6:06 AM

I guess the logic of this depends on where in the chain the level correction is applied.

Kinvermark wrote on 12/12/2018, 7:33 AM

Just to back up a bit...

Are you saying that if you render out a single GH4 file as (for example) an MP4 file that it will have a brightness/contrast shift even if you do nothing to alter the footage? (I assume you are viewing before and after on the same media player. e.g. Windows Media Player.)

Musicvid wrote on 12/12/2018, 10:11 AM

I must manually add "Levels Video Track FX" to every single video track on the timeline?

To me it sounds logical to select "Studio RGB to computer RGB" (Since 16-235 (video) to 0-255) but this makes the image even darker.

"Computer RGB to Studio RGB" is the only option which seems to actually brighten the image.

My strong recommendation is to add the Studio RGB filter LAST, to the Preview (output) FX Buss, just before rendering. Doing this consistently will give a cleaner result and has been tested thoroughly.

espen-braathen wrote on 12/12/2018, 5:06 AM

I guess the logic of this depends on where in the chain the level correction is applied.

Yes. Last in the chain, after editing and correcting to your satisfaction.

I would start by learning the histogram scope intimately.

Well, the standard is 16-235 so this is what Vegas should excpect and correct regardless of what actuall camera manufacturers put into their products

Well, if it weren't for a few minor things, such as lighting, exposure, dynamic range, scene contrast, keying, subject zone and recognition, and IF you were able to tolerate the hours it would take to do complex scan analysis of each scene --- oh, nvm.

OldSmoke wrote on 12/12/2018, 10:41 AM

The SeMW Extension is free and it will do exactly what Musicvid is suggesting.

Musicvid wrote on 12/12/2018, 10:48 AM

The SeMW Extension is free and it will do exactly what Musicvid is suggesting.

Yes, I always forget to mention this, as the old way is already embedded in my workflow.