Video Preview vs. Finished Render (too dark)

Brainwrek wrote on 10/9/2005, 8:43 PM
I'm having a really weird problem. My rendered WMVs are MUCH darker than my video preview window. I can't figure it out. To make the color turn out right, I have to make the video look VERY overexposed in my preview window. As it is, it's impossible to tell if the color balance or contast is set right until after the video is rendered. Any ideas?

Comments

Brainwrek wrote on 10/9/2005, 8:49 PM
I suppose I should give a couple more details.

(1) This is 1080i HD Video captured to M2T
(2) Then rendered to uncompressed AVI
(3) Brightness/Contrast video effect added & adjusted (brightness +8 contrast +15) - looks great in preview window
(4) Rendered to WMV @ 4Mbps & quality 90%
Liam_Vegas wrote on 10/9/2005, 8:56 PM
There are some settings in the Windows Media Player which impact how the video displays. Can't remember exactly where these settings are but it has been discussed in this forum in the past. If I find it... I'll post (or maybe someone else can remember).
Brainwrek wrote on 10/9/2005, 10:46 PM
Yes. I found them under VIEW > ENHANCEMENTS > VIDEO SETTINGS.

But I have them set to the default settings. I suppose everyone just uses the defaults, right? I really want the videos to look right at the default settings.

BTW... this is the first time I've ever experienced this. I just bought a new monster computer, but I'm using the same LCD monitor. Everything looks exactly right *except* the rendered video. This never happened on my old clunky 2.8ghz machine.
farss wrote on 10/10/2005, 2:38 AM
How is the LCD calibrated. Some of the calibration takes place in the drivers.
Safest way to judge these things is with the scopes in Vegas, they will not easily give you an idea of the balance but in general if your video isn't spanning the range from 0 to 255 for a daylight scene then something isn't right with the video.
Bob.
Brainwrek wrote on 10/10/2005, 9:39 AM
I don't have "scopes" anywhere. And I'm very sure this isn't a LCD calibration issue. The AVI looks perfect. The WMV is too dark. Been working on it for 2 days and still can't figure it out. Grrrrr....
David Newman wrote on 10/10/2005, 9:53 AM
Playback within Media player can/will look different than the preview window in Vegas for two reasons.

1) Media Player is more likely to use the YUV overlay surface of your graphics card. This has separate controls for the brightness, contrast and saturation than your primary RGB display output. Many NVidia cards are mis-calibrated, showing the image darker using the YUV overlay than the normal RGB output. This can be fix with simple adjustments with the video cards control panel.

2) More likely you have this: the preview is Vegas shows black and white at the wrong levels by default. Vegas uses "studio RGB" which is a wider dynamic range RGB then what the rest of the windows system uses (this is a good thing). Unfortunately Vegas previews the image in studio RGB (black at 16 white at 235 -- the YUV levels) rather than presenting the image as computer RGB where the black is at 0 and white at 255 (this is how Media Player will show it -- and everything else.) This makes accurate color correction tricky using the desktop display within Vegas, normally a calibrated external monitor is required (then the problem goes away.) If you want to color correct on your desktop display, you need to account for the odd preview representation. So "calibrate" Vegas to match cgRGB (how it will be view after rendering) add the "color correction -- Studio RGB to Computer RGB" filter to you preview window. Color correct using that filter on the output (don't adjusted its properties), but remove the filter when rendering. Now preview and output renders will match.

David Newman
CTO, CineForm
Brainwrek wrote on 10/10/2005, 12:15 PM
Thank you for your reply, _dan_.

But the thing I don't understand is why the AVI looks perfect in Media Player, but the WMV is dark.

I tried both of the solutions you offered, but with only a very minimal improvement.

Also...would changing from Nvidia to an ATI video card fix this problem once and for all?
Brainwrek wrote on 10/10/2005, 1:26 PM
[[ UPDATE ]]

Thank you again, Dan. I reexamined my nvidia overlay settings, and sure enough... that really made a big difference in the way my WMV renders look. WooHoo!

BUT.... does this mean that *everyone* that has an nvidia card (with default settings) is going to see the dark/ugly version of my movies?

If so... that's very disappointing.
David Newman wrote on 10/10/2005, 4:43 PM
It is only an issue with some NVidia cards, and it is straight forward for end users to tweak the levels through Media Player -- but it is unfortunate.

David Newman
CTO, CineForm