Camera shooting levels: 0 - 255?

wwjd wrote on 5/7/2014, 11:22 AM

Curious what you fine gentlemen think about this:

My new gh4 camera has Luminance Level settings: 0-255, 16-255, or 16-235

I would think it would be best to shoot in camera 0-255 to get the maximum range for the recorded material. Then, as usual, condense levels into 16-235 in post.
Might that reduce banding as well?

Regardless of post, I'd like to get the maximum best of everything possible squozed into the camera file - you know, use it to its best capabilities.

Am I thinking wrong here?

Comments

musicvid10 wrote on 5/7/2014, 11:43 AM

Best practice is to shoot just inside 0-255, maybe let specular highlights go, and level in post.
It won't "reduce" banding, it will prevent additional banding in many editing situations.
Shooting at 16-235 discards almost 16% of the available bit depth at the outset. Better to have the full range available for editing, and save the inevitable losses for the last (leveling) step.

Laurence is all over this GH4 stuff. He can give you more specific help.

Laurence wrote on 5/7/2014, 12:37 PM

The GH3 doesn't let you select between 0-255 and 16-235 levels. AVCHD levels are read as 16-235 on a Vegas timeline and MOV levels are read as 0-255. As I've mentioned before, I believe that the MOV levels are also 16-235 and that Vegas is stretching them.

Musicvid has pointed out a theoretical advantage of using 0-255 and that is a higher number of subdivisions of the color range (256 instead of 219). In practice, with Vegas at least, I find this not to be the case. If I shoot in MOV format on either my GH3 or Nikon DSLR, what I find is that that since the 16-235 range is merely stretched to 0-255 that there is no resolution added from this stretch. You can in fact see this on a Vegas histogram where it shows up as evenly spaced vertical gaps where the extra numbers that would be there if not for the stretch are merely skipped. This is in fact another of the reasons why I am so convinced it is a stretch rather than a real range.

What I would recommend for WWJD is to start off with the 16-235 range, record in both AVCHD and MOV formats and see if Vegas reads the MOV footage as 0-255 in spite of this setting. That is what I would expect.

wwjd wrote on 5/7/2014, 1:23 PM

thank you guys! great info.

Is it possible that with Vegas inaccuracies of some things, I should test the range on something better like maybe Premiere scopes that I have temp installed? Would it show more accurate of what the camera is actually capturing range wise?

Lawrence, if you got a gh4, I'm wide open for advice. It's kinda different than my Canon, so, I have lots to relearn. I haven't seen good video out of it yet using my canon techniques.

markymarkNY wrote on 5/7/2014, 1:23 PM

Ever since I got my GH3, I have abandoned Vegas for some of my color correction because I don't know what is happening to the levels. Instead, I just import the native mov files into the free version of Davinci Resolve. I do corrections on individual clips using the color parade and other tools where I can easily see the 0-255 and then output it as 16-235. I use MXF for rendering. Then I bring all those MXFs into Vegas for composing, editing, stabilizing, etc.

It may seem like extra work, but I find the Davinci workflow and GUI to be easier than Vegas for coloring. Davinci is terrible for timeline work.

I have the GH4 now and have shot some stuff in 4k but I haven't gotten around to any editing yet. I intend on 1920 delivery so we'll see if the downres is all it's cracked up to be to get true 1920x1080 resolution.

Fun camera to work with - loving the zebras, focus peaking, and monochrome live view!

Marco. wrote on 5/7/2014, 2:12 PM

"You can in fact see this on a Vegas histogram where it shows up as evenly spaced vertical gaps where the extra numbers that would be there if not for the stretch are merely skipped."

Possibly Vegas Pro or Quicktime does so for a very certain kind of MOV video. Usually Vegas does not do this. As you pointed above, histogram could tell you if it happens (dependend on the character of your video signal). See -> here (if you count the missing values: it's 36 for R', G' and B' …).
Usually Vegas Pro lets your input signal totally untouched which is a manner I really appreciate since the first day I used Vegas (which was version 2 long time ago) but video which passes Quicktime is critical in this manner.

.

Laurence wrote on 5/7/2014, 3:33 PM

Yes, I believe that technically it is not Vegas that is stretching the levels. It is likely something about Quicktime that is doing this. None the less, they are stretching on a Vegas timeline. That and when played back by VLC. In WMP, Adobe or ProDad software the levels are not stretched.

wwjd wrote on 5/7/2014, 3:39 PM

is there a PNG JPG or screen I can film to help display the levels?

NormanPCN wrote on 5/7/2014, 3:41 PM

Vegas special cases Quicktime MOV files when the video is AVC and the audio is PCM. In this case it uses its own decoder. You can tell if Vegas is using Quicktime, or which internal decoder it is using by looking at the media properties dialog, general tab. qt7plug is quicktime and compoundplug is the normal internal decoder.

Marco. wrote on 5/8/2014, 3:11 AM

I'm not sure if it works if you shoot a PNG displayed on a LCD panel. You could download and unzip this file if you wanna try.

Else it should work with any wide spread color gradient you'd find in nature, maybe kind of sunset scene.

wwjd wrote on 5/8/2014, 8:31 AM

thanks marco, I have access to an ok color printer with photo paper so I plan to print that and some other tests, and shoot some tests.

Laurence wrote on 5/8/2014, 9:00 AM

Try the GH4 AVCHD modes. Vegas won't stretch the colors so you'll be able to see where they really are.

wwjd wrote on 5/8/2014, 9:09 AM

lawrence, I will try it strait to AVCHD tonight.

This from my other post:

one problem I run into is that video scopes seem to grow beyond the 0-255 range depending on the SIZE of the preview setting??? VP12 & 13. this is using 4k material. and the vector scope colors also shoot off the chart - past 100 - as I change the size of preview... what the freak? maybe not designed to deal with 4k?

and although I set the camera to MOV, not AVCHD, Vegas shows it playing back with SONY AVCHD and not QT under the properties detail.
soooo, not sure how to read what I am seeing here.

Marco. wrote on 5/8/2014, 10:21 AM

Ah, yes. Using the scopes you must set the preview to "Best (Full)". You can't trust the scopes with any other preview setting and also the project properties must match the analyzed media properties.

Marco. wrote on 5/8/2014, 5:06 PM

I just saw same level stretching happens when importing MP4 H.264 video from the GoPro though Vegas Pro uses the compoundplug.

musicvid10 wrote on 5/8/2014, 8:14 PM

Nvidia graphics users be aware -- this reported level expansion may be device-specific, and not related to software decoding.

Laurence wrote on 5/8/2014, 8:31 PM

[i]> I get the stretch with GoPro footage as well. It's tho only non-MOV format I have seen do this.

musicvid10 wrote on 5/8/2014, 8:37 PM

What are you comparing it too? If a player or Premiere, there is another factor with GoPro called a fullrange flag that has rather spotty support. Vegas doesn't have it.

Marco. wrote on 5/9/2014, 4:02 AM

No Nvidia in this case. But also tested with several Windows systems and cross-tested with different encoding formats and files. There is definetely a certain type of video which levels are stretched by Vegas. I remember same happened (or still happens) with the Mercali output.

Edit:
If you have a Vimeo account – test yourself. Download a GoPro sample and analyze in Vegas Pro. You'll find the original sample download in Vimeo's download dropdown menu:

vimeo.com/32247572

.

musicvid10 wrote on 5/9/2014, 7:40 AM

Heh - I seem to be directed to Gordon Laing's Vimeo page a lot lately . . .

Downloaded the original source, My Vegas shows levels that are essentially 16-235. Effects chain is empty. You getting something different? What decoder is Vegas using?

Vegas Pro 8, Vista 32, Quicktime 7.6

Marco. wrote on 5/9/2014, 7:57 AM

Ah, this could be a difference between Vegas Pro 8 and newer versions. I'll see if I have any system available with an older version to compare.

VP13 uses "compoundplug" for decoding and the histogram looks like this:

…

Oooooops. Now it looks like yours and no stretching is done!
This is very strange. I'll see if I made a big mistake yesterday or if there is something like a bug which triggers different types of decoding (though actually I would not have expected stretched levels if Vegas uses the compoundplug for decoding).

Edit:
Between the time the GoPro file showed stretched levels and today there I installed ClipToolz Convert (because I'm looking for a tool to trim GoPro files and export to XDCAM HD). And ClipToolz Convert installs ffmbc. Maybe this made the difference. I'll test with another system …

musicvid10 wrote on 5/9/2014, 8:12 AM

Yes, Vegas 8 uses Quicktime to decode these .mp4 files.
It was handed over to compoundplug.dll as of Vegas 10.
Nick and I saw some differences with MOV files as well.
Just wondering where it stands today.

(ffbmc shoud have nothing to do with it).

Marco. wrote on 5/9/2014, 8:16 AM

"ffbmc shoud have nothing to do with it"

I think same but I never trust any codec installation. I'll test later.

wwjd wrote on 5/9/2014, 8:45 AM

k, my mind is blowing. so, when watching levels, trying to keep things within the reasonable range of 16-235.... if one changes the PREVIEW, OR uses different file types or decoders, the viewed levels STRETCH OUT showing different ranges? How are we supposed to color and grade with an ever changing target?

I can grasp the efficiency of coding the graphs to use the preview as THE levels source, changing with more detail in a larger preview... but is it REALLY showing proper useable info if it goes from 18 to 4 to something way below 0 and not seen when changing preview sizes?
No way I can edit 4k in full size... I'd only see a belly button! hahahahaha

Marco. wrote on 5/9/2014, 10:46 AM

If you change the preview properties (which includes the project properties) it does not necessarily stretch the levels shown in the scopes but it does alter many pixel values so the scopes view may differ in some way.