YouTube, levels and monitors, a simple test.

musicvid10 wrote on 6/15/2011, 9:53 PM

On my VAIO notebook with screen calibrated (0-255 RGB) as close as I can get it.
By that I mean 0-4 crushes when 255-252 is adjusted to show differentiation.

No correction = solid black throughout
Correction applied = gray "16" swatch + solid black bars

johnmeyer wrote on 6/15/2011, 11:25 PM

I am a little unclear exactly how I am supposed to interpret my results. I get the same results as MusicVid when watching the clip natively on the YouTube page:

No correction = solid black throughout
Correction applied = The vertical bar containing "16" becomes dark gray

So, what does this mean about my monitor, and what does it imply for my workflow? Every time I think I am starting to understand this, I get another post by Nick Hope, or MusicVid, or Glenn, or someone else who knows a lot more about this than I do, and I feel like I have to go back to square one.

Munster1 wrote on 6/16/2011, 12:58 AM

I think you are seeing what you are supposed to be seeing in that video. It's hard to draw any conclusion from it since we don't know what format was uploaded in the first place. Also it's one clip, not two separate clips with different adjustments

The thread below helped me understand the process with display and output levels in Vegas. The glennchan articles linked were particularly helpful.

http://forum.videohelp.com/threads/333752-How-do-you-get-the-blackest-black-when-rendering-in-H264

farss wrote on 6/16/2011, 1:45 AM

"So, what does this mean about my monitor, and what does it imply for my workflow? Every time I think I am starting to understand this, I get another post by Nick Hope, or MusicVid, or Glenn, or someone else who knows a lot more about this than I do, and I feel like I have to go back to square one. "

I will not claim to know more about this than anyone else but I do like to get to the bottom of things. So here's what it's about.

Based on the feedback so far it seems most computer monitors are setup for Computer RGB i.e. 0 to 255..
Most cameras (except for vDLSRs) record levels in Studio RGB i.e. 16 to 235, some go higher to 255.

That black swatch is at standard video black levels.
Looking at it on all but one of my monitors it looks grey, only one of my monitors is setup to display video correctly.

It looks black played back on YouTube because YT are applying a levels expansion. They know most of their users aren't video engineers, in fact many today are uploading video directly from their phones and cameras. So what YT is doing makes a lot of sense. Black comes out as black. Even if you upload footage graded for broadcast it will come out correctly on what most people view video from YT on. Of course if you watched it on a broadcast calibrated monitor it'll be wrong / clipped.

So now that I'm seeing that so far everyone is watching YouTube on a Computer RGB calibrated monitor then I'm fairly confident in saying that the advice to apply a Levels FX using the Computer RGB to Studio RGB preset for uploading to YT is not good advice. You will shift the blacks up, you'll get most of your viewers seeing video with "setup" on the blacks.

I devised this test because it's not all that easy to see this. Most computer LCD monitors are horrid in the blacks anyway. Trying to judge a black swatch in the middle of the frame is hard, I'd not really picked this up before, I though there was a problem but I needed to devise a test that'd prove it. One reason I used 4:3 footage was to force YT to add pure black bars to the side of the frame as a reference.

Bob.

amendegw wrote on 6/16/2011, 2:50 AM

fwiw, I see the same results as musicvid & johnmeyer:

No correction: Solid black
Correction applied: Gray bar (I measured it at 15,15,15 - experimental error?)

This is on my Dell Studio 15 laptop. Detailed specs are in my profile.

...Jerry

NickHope wrote on 6/16/2011, 3:40 AM

This subject could go round and round in circles forever. Basically there is no shortcut for knowing what levels your camera shoots and understanding how that affects what you should do with the levels in post.

Maybe we should maintain a list/database. Would be really useful for this stuff. i.e. Column 1: Camera make and model and year of purchase. i.e. Column 2: Level of footage with lens cap on and gain set to zero. Column 3: Level of footage pointing at the sky with open iris/long exposure.

If anyone has suggestions for a fail-safe, generic way to get your camera's maximum white level, please let us know, then I'll start a survey thread. I assume we shouldn't be advising people to point their camera directly at the sun.

Anyway my results are the same as the others:

No correction = solid black throughout
Correction applied = The vertical bar containing "16" becomes dark gray

farss wrote on 6/16/2011, 4:12 AM

"Basically there is no shortcut for knowing what levels your camera shoots and understanding how that affects what you should do with the levels in post."

Amen to that. I recently got quite taken by surprise by exactly this.
I had some footage shot on the CX500 in standard def of all things and it was to be uploaded to YT. When I checked the levels on the scopes it was spot on legal, never a blip over.
Pretty sure in any of the HD modes it doesn't do that. The catch I think is this cameras also can burn directly to DVD so keeping the levels "legal" makes a lot of sense in a confusing kind of way.

Aside from that oddity though pretty well every other camera will shoot 16 to 255 which is neither Computer or studio RGB. The exception to that are the vDSLRs, they shoot video the same way they take stills, Computer RGB levels.

In general for uploading to YT probably the safest thing is to follow Glenn's articles on making the video broadcast legal. Then no matter what you do with it it will all come out correct either on tape, DVD or on YT.

Bob.

Munster1 wrote on 6/16/2011, 9:30 AM

Below is a link for Nick Hope's article on video uploads to Youtube. It basically confirms that luminance should be between 16-235 for most formats uploaded to Youtube with the main exceptions being wmv and certain avi types which need to be 0-255.

http://www.bubblevision.com/underwater-video/YouTube-Vimeo-levels-fix.htm

NickHope wrote on 6/16/2011, 11:22 AM

I've learned more since writing that article and I need to modify it a little, especially part 2 which is a bit rash in recommending a blanket C-RGB to S-RGB filter. But the distinction between which formats do and don't come back with levels expanded is still correct as far as I know.

DavidMcKnight wrote on 6/16/2011, 1:16 PM

Same as what many have reported, no levels = black, with correction applied a slight gray. <edit> this is on a standard PC monitor, not what we'd cc on.

farss wrote on 6/16/2011, 2:59 PM

Nick,
the fundamental problem seems to me to stem from people monitoring video with computer monitors "calibrated" for computer RGB. If you are doing that then you are looking at your video incorrectly in the first place.
If you then send that video to YT it will expand the levels for correct viewing on a computer monitor.

If you start looking at it on a computer monitor (wrong), shift the levels for YT (wrong) you will see back what you started with. You're now into the "two wrongs don't make a right".

If you are using a computer monitor you need to apply the Studio RGB to Computer RGB adjustment to the monitor in the first place.
Then you do nothing to the image, send it to YT as H.264 as per the tutorial and watch it on your typical computer monitor and it will look the same, ignoring the other variances been computer monitors.

All of this is why since day one of Vegas and any other NLE for that matter we've been told to use calibrated CRT monitors.

Bob.

paul_w wrote on 6/17/2011, 7:14 AM

Bob,
This is why i always preview now on an external PC computer monitor but with "Use color management" tick box selected and with "Use studio RGB (16-235)" tick enabled.
Previews on external monitor are now correct wysiwyg, and as far as i can tell with real world testing with Vimeo, it looks perfect to my eyes once uploaded and played back in the flash browser player. This goes for DVD renders too.
I'm sure there is fine tuning that could be done for the perfect result, but honestly i think it looks perfectly acceptable.
Paul.

farss wrote on 6/17/2011, 1:05 PM

Paul,
yes, you are doing it correctly. Yes If you start with monitoring on a correct monitor, upload it and then view it on a computer the results match. YT and Vimeo apply the correct levels expansion, the same as what Vegas does with that "Use studio RGB(16-235)" tick enabled.

Bob.

Serena wrote on 6/17/2011, 11:04 PM

Gee, it's Saturday and you want me to get my brain into gear! On my laptop I see the grey bar 16 when correction levels applied, but on my Vegas monitor I see black all the time. Now, darn you, I have to work out what I understand from that.

Munster1 wrote on 6/18/2011, 12:22 AM

Perhaps this should be mentioned to avoid some potential confusion:

Youtube doesn't actually expand the luminance in the video itself, the expansion happens at playback on your PC.

farss wrote on 6/18/2011, 3:47 AM

"Youtube doesn't actually expand the luminance in the video itself, the expansion happens at playback on your PC."

Indeed and the reason I suspect Serena is the only one seeing what she's seeing is she has a monitor setup to correctly display video.

Bob.

NickHope wrote on 6/18/2011, 5:31 AM

I think you're right Bob. When I surveyed this a while back, I seem to recall Serena's was the only computer other than my laptop to see any grey in

because of how she had her display set up. Since that time, Flash Player updates have made my laptop start behaving like most other people's computers.

JohnnyRoy wrote on 6/19/2011, 7:29 AM

> "Youtube doesn't actually expand the luminance in the video itself, the expansion happens at playback on your PC."

Yes this is what I'm seeing too. AND... what you see seems to be affected by what software you use to play it back on.

I did some testing of my own and this is what I'm seeing. I'm not sure how to interpret this, but I offer it to the community for your consideration:

I created this project which you can download from my web site and make your own tests and conclusions:

LevelTest.veg

This is what the project looks like in the Vegas preview:

Preview

I render the project as Sony AVC using the Internet 1280x720-30p template and then watched the video in various players as well as uploading to YouTube. This is what I'm seeing:

Here is the video playing in VLC:

Here is the video in QuickTime Player:

Here is the video in Windows Media Player: (note it expands the levels)

Here is the video as seen on YouTube: (same expansion)

It appears that Windows Media Player and YouTube are absolutely expanding the video on playback because it looks fine in VLC and QuickTime. Also, I can download the video from YouTube and play it in VLC and the levels are back!!! So the video is not changed by YouTube otherwise the downloaded video would not have the correct levels. Perhaps it's the Adobe Flash plug-in?

This is very strange because I can add Computer RGB to Studio RGB to make it look fine on YouTube but if someone downloads my YouTube video it will look washed out on their computer unless they use Windows Media Player which performs the expansion again. I'm not sure how to fix this, but those are my findings.

~jr

amendegw wrote on 6/19/2011, 8:00 AM

What did Alice once say? Things are getting "Curiouser and curiouser."

I can't duplicate your tests (except the WMP & I YouTube [I assume]). I see levels expansion in all local players (consistent with what we saw in musicvid's monster thread).

VLC:

Quicktime:

WMP:

...Jerry

Edit: btw, my render was in 10.0d 64bit (I know the Sony encoder has changed in 10.0d)
Edit2: Should have posted my Vegas Preview:

Edit3: Addressing farss post - several posts down. The following Vegas Preview Screenprint has the sRGB to cRGB FX applied.

Marco. wrote on 6/19/2011, 8:27 AM

It depends on the grafic card settings.

Dependend on which setting I use for my NVidia card almost any player displays the differences between 0-16 and 235-255 (even WindowsMediaPlayer does).

Btw: Even when I playback the MP4 file via my standalone media player (WDTV) on my TV (Panasonic LCD) I see the differences between 0-16 and 235-255.

Munster1 wrote on 6/19/2011, 8:33 AM

From what I recall neither VLC or Quicktime player expand levels internally, unlike some other players.

To get levels expansion in VLC or Quicktime, video dynamic range has to be set to 0-255 by the graphics card driver. There is a setting for that in the Nvidia control panel (can't speak for ATI cards).

Edit: If you render the levels test as WMV, no levels expansion is applied on playback, since the codec is designed for ComputerRGB levels (unlike an mp4 render which is expanded).

musicvid10 wrote on 6/19/2011, 9:42 AM

VLC player expands YUV levels on playback.
We have run many tests on this.

Quicktime Player is a crapshoot.
I wouldn't even go there.

WMV does not play back at expanded levels, true.

NickHope wrote on 6/19/2011, 10:15 AM

Dell laptop, NVIDIA Quadro FX 1600M, XP SP3: None of these players expand the levels. I see 4 shades in all of them:

VLC Player
Quicktime
WMP 11
GOM Player
Media Player Classic
IrfanView
PowerDVD

(EDIT: Updated results are in my table further down the thread)

NEC desktop, Intel Q965/Q963 Express Chipset Family, XP SP3: All of these players expand the levels. I see just black and white in all of them:

VLC Player
Quicktime
WMP 11

Marco. wrote on 6/19/2011, 10:24 AM

"VLC player expands YUV levels on playback."

It does if used with its default setting.

But if you disable the VLC hardware acceleration while you leave the YUV-RGB switch as it is (enabled) even VLC works without level expand.

I have another AVC test video with RGB 249 text on 255 background and RGB 8 text on RGB 0 background which is visible also when playbacked via VLC player.

I think FlashPlayer and DivX Player are one of the very few which does not allow to disable a level expand.