YouTube, levels and monitors, a simple test.

Munster1 wrote on 6/19/2011, 10:34 AM

VLC player only expands YUV on playback if the graphics cards video dynamic range setting is 0-255 (unless there is another setting hidden away inside VLC I've never found). Same thing occurs in Quicktime. By altering the video color settings in the Nvidia control panel I can turn the expansion behaviour on or off for both players.

The WMV codec expects to see ComputerRGB luminance levels (0-255) when encoding as opposed to StudioRGB levels (16-235). Does that clarify my statement?

musicvid10 wrote on 6/19/2011, 10:40 AM

Most of us don't have graphics cards that allow us to specify 0-255 or 16-235 levels.
Am I safe in assuming that your Nvidia default is 0-255 RGB?

Munster1 wrote on 6/19/2011, 10:57 AM

Originally the default was "video player settings" which resulted in no expansion in VLC or Quicktime (MPC-HC playback was fine) and most videos looked a bit washed out.

I changed it to "Nvidia settings" with full (0-255) dynamic range when I got a bit of advice from another forum some months ago. Since then every video has played back fine in terms of contrast.

amendegw wrote on 6/19/2011, 11:16 AM

Okay, now things are beginning to make sense. I do most of my testing on my laptop with ATI Mobility Radeon HD 545v (that's where I got my screen captures above). Can't find any levels settings in the "Catalyst Control Center".

However, opened the same test mp4 file on my nVidia nVidia Gforce 9500 GT workstation and low-and-behold the levels in VLC were not expanded. Looked in the nVidia settings and here's what I found:

Note that the default is "use video player settings". Just to be clear - I took the above screenprint after I played with the settings. With the default "use video player settings", there was no expansion.

...Jerry

PS: Did I mention I love this forum 'cuz I learn something new every day?

Marco. wrote on 6/19/2011, 11:20 AM

Yes, used "With the video player settings" VLC player and most other ones can be used without a level expand. I did not know this is the default setting.

Munster1 wrote on 6/19/2011, 11:24 AM

I do have "Dynamic contrast enhancement" turned off because it has done some odd things visually in the past (driver issue perhaps).

musicvid10 wrote on 6/19/2011, 11:55 AM

Jerry, interesting revelation about newer Nvidia graphics if their default is not 0-255 RGB. Just another monkey wrench for the confounded afaiac.

So I'm sure you are testing this as we speak, but I'm anxious to hear what the Nvidia controls do to Flash, YT, Vimeo, JWPlayer, et al, if anything.

NickHope wrote on 6/19/2011, 11:56 AM

I don't have the luxury of an "Advanced" tab on my Dell laptop (NVIDIA Quadro FX 1600M). Changing between "video player settings" and "NVIDIA settings" has no effect. None of the players will expand the levels. To approximate that I would have to adjust the contrast in the players themselves or in the NVIDIA color tab. But from previous tests, it seems likely that this laptop is in a small minority in behaving this way.

EDIT: p.s. The default was "video player settings".

Marco. wrote on 6/19/2011, 12:03 PM

I have a Dell laptop with same grafic card but with advanced control when used with Nvidia settings (the choice between 16-235 and 0-255). My Nvidia driver version is 186.81. Maybe it's the driver version which brings the advanced control.

NickHope wrote on 6/19/2011, 12:16 PM

My driver is 175.75 which is the latest certified one offered on the official Dell support site for my particular model. The Nvidia site is offering me version 275.36.

I'm already out of the 3-year warranty. Do you guys think it's safe(ish) to pull the trigger?

Munster1 wrote on 6/19/2011, 12:24 PM

@ Nick Hope

I got a different driver offered when I searched for your card:

http://www.nvidia.com/object/notebook-winxp-266.58-whql-driver.html

farss wrote on 6/19/2011, 1:06 PM

To state what should be the obvious if you can see the difference between 0 and 16 in the Vegas preview monitor it is NOT setup correctly.

It's kind of frustrating, heck even embarassing, that after all the work Glenn Chan and others have put into simply explaining all of this that still people here will not take the time to read and learn how to setup a video monitor correctly.

I'll say it again. The internal preview monitor needs to have a Levels FX applied to it using the Studio RGB to Computer RGB preset. Then you will not see the difference between 0 and 16.

If you are using the Secondary display Vegas provides a switch to do this. As some have realised most modern video cards also provide this switch, it should be ON.

Bob.

Marco. wrote on 6/19/2011, 1:22 PM

I'm glad the Vegas preview shows me all the information that is in the video. I don't want it to behave any other than it does. "Correct" is an ambivalent term sometimes.

amendegw wrote on 6/19/2011, 1:31 PM

Okay, I finished my testing on the three late model computers I have at home. Using "default" settings on everything, here's what I came up with viewing the file rendered from Johnny Roy's veg posted above.

This is very consistent with JohnnyRoy's screenprints above - bet he's got an nVidia card. btw, for web testing, I tried IE9 & Chrome. Didn't seem to make a difference in the web based players.

...Jerry

Edited to correct the Silverlight Error.

farss wrote on 6/19/2011, 1:32 PM

" "Correct" is an ambivalent term sometimes"

That is true to some extent however in the world of video there is no ambivalence, there are defined standards and they should be adhered to.
I don't bother about what the internal preview is doing, I know it's wrong and would never use it to make critical judgements.

However to be showing screenshots of it here setup incorrectly and then run around saying The Sky Is Falling Down is simply spreading FUD.

Bob.

Munster1 wrote on 6/19/2011, 1:58 PM

I thought we were talking about Youtube and media player levels expansion, not the Vegas preview window (which isn't affected by the Nvidia card video dynamic range setting btw).

farss wrote on 6/19/2011, 2:44 PM

"I thought we were talking about Youtube and media player levels expansion, not the Vegas preview window (which isn't affected by the Nvidia card video dynamic range setting btw). "

Yes, we were.
YouTube doesn't "expand levels", it correctly displays video. It does this because the majority of people, as this test shows, are going to view video on computer monitors.

The Vegas preview window is not affected by the video overlay settings in the drivers because THAT preview does not use the video overlay, hence the need to apply a correction to it if you want to gauge video in it. Vegas's Secondary Display does, it has a switch for that very purpose.

If you don't make the effort to understand this then even within Vegas itself you can get confused switching between internal and external preview.

Bob.

musicvid10 wrote on 6/19/2011, 4:28 PM

Thanks Jerry, for taking the time to do that.
So for some people with Nvidia graphics, the same video will play one way on Youtube and another way VLC. Simply brilliant what they come up with to confuse consumers more.

johnmeyer wrote on 6/19/2011, 7:09 PM

For those who can't get enough of this topic ;), or are finding themselves (like me) getting more confused as these levels threads get longer, here is another source of information (and confusion) that may be helpful. If nothing else, it does provide an answer for ATI users as to how to adjust their card (warning: registry hack involved).

Doom9.org - Page FAQ: How to correct luminance levels

NickHope wrote on 6/19/2011, 10:34 PM

Munster1 said: "I got a different driver offered when I searched for your card"

I also got that version by searching manually but I didn't quite trust that it was the right update so I used their browser app to automatically detect and it then offered me version 275.36.

So now I've installed that updated driver and lo and behold I now have an "advanced" tab. According to John M's great link above, it was introduced in driver version 177.84, which I guess must have been a good 3 years ago. I did a "clean" update to set everything back to defaults and the default is to make color adjustments with video player settings. If one switches to using NVIDIA settings, the default is then 16-235.

So I've run through a bunch of tests here and below are my findings:

So for this graphics card's default, none of my media players "expand" the levels, even with the bang-up-to-date driver. One must first switch to make adjustments "with the NVIDIA settings", and then set it to 0-255. Something only a small minority of tinkering users would do.

John R and Jerry, I'm interested to know what video codec your WMP is using to play this file. That should explain why it is "expanding" levels even when the graphics card is set to use video player settings. To find out, open the file in WMP and choose file > properties. Mine is using ffdshow and doesn't expand. Also John R, please confirm your video card make and driver version. Cheers.

p.s. Bob, apologies to constantly use these terms "expand" and "squeeze" levels, but I can't think of a more concise way of conveying the concept.

musicvid10 wrote on 6/19/2011, 10:43 PM

Nick,
I assume your results for Youtube (always expands) are consistent for Vimeo, JWPlayer, and standalone Flash Player as well?
I have no indication otherwise, but just to be sure, since there have been a couple of ground tremors since first publishing the Youtube tutorial.

;?)

NickHope wrote on 6/19/2011, 11:22 PM

Where do I test? I spent a bit of time hunting on Jerry's site for the embedded test videos but failed and was too lazy to trawl the monster thread so I deleted those lines from my spreadsheet.

farss wrote on 6/20/2011, 2:01 AM

Ladies and Gentlemen,
the reason for so much of confusion is due to starting with the wrong assumption. Get your initial understanding correct and then it will all seem ever so much simpler. Glenn Chan has gone to great lengths to explain all of this. Perhaps if I distill it down a bit (hopefully without making it too simple or getting something wrong) it will all become a bit clearer.

1) The Vegas Preview monitor out of the box on an out of the box computer monitor does not display video correctly. It is absolutely vital to understand this. Taking screen shots of that and comparing it to anything else will lead you a merry dance.
To the best of my knowledge you can calibrate that monitor to absolute precision using a Spyder etc and it will still be wrong, none of the calibration profiles are likely to be correct. Please note that the "sRGB" colour space is NOT the same as "Studio RGB".
To correctly view video using Vegas you must do one of the following.

a) Apply a Levels FX to the Video Bus / Monitor with the Studio RGB to Computer RGB preset. Before rendering you must disable this FX.

b) Use the Secondary Display setup as shown here:

Note in particular the checkbox I've highlighted. Ticking that box does the same thing as applying the FX I mentioned for using the Internal Preview Monitor.

c) Use an external CRT monitor with a digital to analog converter connected via firewire. This is not such an easy option as CRT monitors are no longer in production

d) Use a proper LCD or OLED video monitor connected via SD SDI or HD SDI. This is the best option but extremely expensive. I mention this only to cover all the bases.

2) Video, both HD and SD, effectively defines 16 as black and 235 as white. If anything in your video is outside these levels you will have problems.
a) If you make a tape or a file and send it to a TV station you'll most likely get it rejected with a nasty letter.
b) If you make a DVD from that video you'll find that the DVD player will clip anything below 16 and above 235. It does this to get this video "Correct" because if it didn't several things can go wrong, one being the TV loose sync and roll if the video levels go below 16.
c) If you encode that video and upload it to Vimeo or YouTube it will also get clipped. Values below black and above white will be clipped.

3) Almost nothing in Vegas creates correct video by default. The Generated Media and text generator defaults are wrong, they use computer graphics levels. I use my own presets prefixed with "Legal"e.g. "Legal Black" (16,16,16), "Legal White" (235,235,235) etc.

4) Images from Digital Still Cameras and scanners are in Computer RGB and need to have their levels altered to conform to video levels. There's a bit of a catch here. If you do not setup your monitors in Vegas correctly they will actually appear correct. Two wrongs can make a right. Problem is down the track you may come unstuck.

5) Video from DSCs and DSLRs such as the 5D, 7D and GH2 are also in Computer RGB and need to have their levels adjusted. Again you can get caught out as in 4). Get everything correct to start with and life will be ever so easy.

I know I've said much of this before but still it seems not to be getting through. Once you get this understood then the next big issue should be "What is displaying video correctly?". In part many things don't, they're seems to be some effort today to get things in order but there's still a lot of legacy devices around that get it wrong or even worse as I've found out, two things in the chain both trying to "fix it" and creating a very ugly viewing experience.
If you do find something displaying legal, correct video incorrectly then you should deal with the problem there as best you can. Changing your video to compensate is fraught with dangers. Sometimes of course that might be the only option, just remember to undo what you've done for everything other than the errant device.

Bob.

NickHope wrote on 6/20/2011, 2:47 AM

Bob, I think most, if not all, participants in this thread already know the gist of that and understand that the Vegas preview window doesn't display full range. I'm wondering which part of the above discussion makes you think that the message hasn't got through. As I see it, the discussion is now about why some graphics cards and some media players (other than the Vegas preview) display video differently from others.