Dynamic Contrast ??

Forums › Home Theatre (including HTPC and EPG Collector) › Dynamic Contrast ??

aucklander

478 posts

Ultimate Geek
+1 received by user: 11

#23498 1-Jul-2008 08:14

This happens pretty much all the time, I would say more often on TV3 than other channels. The image changes contrast, in my opinion on a random basis, as some times it does it during the same scene, with no major change in scene composition (light, subject changing position, etc). It is perceived as a sudden increase in luminosity, but a lack of contrast. I would say sometimes the image looks "milky". At the other end, is a good nice contrast.

The tv is not unwatchable, but I find it very annoyng. The TV (Sony Bravia D series) has in its menu a feature named ACE (Advanced Contrast Enhancer), which does exactly that, dynamically adjust contrast during playback. I had this feature turned off, but the image still does that.

So, I assume is from my video card. Reading a list of features the 8600GT has, the "dynamic contrast" shows up again. (What do these people have with this feature?). The problem is, the nVidia interface is sooooo basic, you can adjust colours and screen resolution, and... well, that's pretty much it. Not even screen position adjustments!

Is there a way to access all the super-features listed for the graphic card?

It also says "Purevideo HD" on the list. But a deeper search on the net revealed there some download (which is NOT freeware), like a driver, to get Purevideo HD working. What's the story with that? On the box says DirectX 10, but the installation CD comes with DirectX 9.0c; I think the list shows what the product CAN do, not what it DOES "out of the box".

I used DVI/VGA and DVI/HDMI signal to the tv, same story. (That means is not the cable, right?). The card has component output, didn't try that yet. I don't see why the "component" should be better than DVI/HDMI.

Any ideas how to get rid of that contrast change?

mobo Intel DH55PJ, RAM: 4GB RAM, Nova-T 500 HD + Avermedia Trinity tuner card, Geforce 520 video, 120GB SSD Sandisk + 640 WD + 1000SG, Win7 Home Prem 64-bit, Media Portal 1.15.0; BTC 9019URF Cordless Keyboard, Panasonic 55" (HDMI cable), HTPC Case Silverstone Grandia GD05B.

1 | 2

29098 posts

Uber Geek
+1 received by user: 10207

Trusted

Lifetime subscriber

#141892 1-Jul-2008 14:21

Do you have a picture mode thing that cycles thru options with one of them being dynamic? I recall that on an older LCD, when on dynamic it was horrible unless you had the lights on - background was bouncing between grey and bright grey all the time.

The other options had less brightness but it was more constant.

Richard rich.ms

1gkar

722 posts

Ultimate Geek

#141954 1-Jul-2008 17:17

aucklander:
This happens pretty much all the time, I would say more often on TV3 than other channels. The image changes contrast, in my opinion on a random basis, as some times it does it during the same scene, with no major change in scene composition (light, subject changing position, etc). It is perceived as a sudden increase in luminosity, but a lack of contrast. I would say sometimes the image looks "milky". At the other end, is a good nice contrast.

Best to leave all of the so-called expert features off when connected to an HTPC. From what I've read on various AV forums, they are very personalised anyway. Some like 'em, some don't. My receently purchased Samsung R8 LCDTV comes with all extras disconnected when using the PC (VGA) connection -haven't gotten around to setting up HDMI, yet. Still enjoying the superior visual experience from my old 29" CRT

The tv is not unwatchable, but I find it very annoyng. The TV (Sony Bravia D series) has in its menu a feature named ACE (Advanced Contrast Enhancer), which does exactly that, dynamically adjust contrast during playback. I had this feature turned off, but the image still does that.

So, I assume is from my video card. Reading a list of features the 8600GT has, the "dynamic contrast" shows up again. (What do these people have with this feature?). The problem is, the nVidia interface is sooooo basic, you can adjust colours and screen resolution, and... well, that's pretty much it. Not even screen position adjustments!

Is there a way to access all the super-features listed for the graphic card?

There should be more user options than what you have stated with Nvidia's control panel. Maybe you set it up for standard mode. To get advanced mode, right-click desktop>NVIDIA Contro Panel. Click view ( on menu bar) & it will tell you which mode you are in. Just click advanced which should bring up the full list of options in the left side tree.

Though on quick perusal my card (Asus EN8500GT) has nothing about dynamic contrast. Maybe it's manufacturer specific? Or is it an option with 8600 cards?

It also says "Purevideo HD" on the list. But a deeper search on the net revealed there some download (which is NOT freeware), like a driver, to get Purevideo HD working. What's the story with that? On the box says DirectX 10, but the installation CD comes with DirectX 9.0c; I think the list shows what the product CAN do, not what it DOES "out of the box".

PurevideoHD is no good with FreeviewHD as it only works with MPEG2 video, not H.264-MPEG4 files. Not sure how it comes into play with Blu-Ray movies. The info on this codec is pretty poorly described on Nvidia's website.

I used DVI/VGA and DVI/HDMI signal to the tv, same story. (That means is not the cable, right?). The card has component output, didn't try that yet. I don't see why the "component" should be better than DVI/HDMI.

It's not. Component is analogue: top of the line connections, but still analogue. DVI>HDMI is best, followed by DVI>VGA.

Any ideas how to get rid of that contrast change?

Apart from what I've already said, no, except, can you disconnect LCDTV & try a PC monitor, see if the same occurs on this screen & stick with the digital interface. What is you're video card make & model?

Silverstone LC14 HTPC Case/Intel E4600 CPU/GA-EP35-DS3 MOBO/Asus EN9500GT graphics/2GB RAM/total 2TB HDD space/HVR-2200 & 2X 150MCE tuner cards/LG GGC-H20L BD Drive/MCE2005/Mediaportal/TVServer 1.1.0Final/LG 55"3D LED-TV/Denon AVR-1803 receiver/X1 projector

Vorbis

176 posts

Master Geek

#141978 1-Jul-2008 18:37

The cd will have directX9 in case you are installing the card in an XP machine. DX10 is Vista-only, and the blurb on the cards' 'features' simply means it supports DX10 apps.

aucklander

478 posts

Ultimate Geek
+1 received by user: 11

#142101 2-Jul-2008 08:15

The recorded shows have the same change in contrast. There is no way to say for sure they occur exactly at the same time (which means they are part of the recording), but they are still visible on the recorded shows. But this could still be generated by the Tv during play-back, right? I had the optional features turned off on the TV, the contrast change still occurs.

I reverted from 177 drivers to 175 as somebody else said that fixed the problem and the HD movie on TV3 showed no "low framerate" effect anymore. I used to get a lot of that until Monday, with 177 drivers. But strangely enough, the recorded shows were ok, no "low framerate" effect at all, the Tv3 recording was very smooth, same as TV1 and Tv2 (I watched and recorded at the same time, for testing purpose). The jittering on live tv did not dissapear when recording stopped (innitially i assumed there is not enough processing power and the recording has a higher priority, somehow, and the timeshifting function is basically a recording).

If you record the same channel you are watching, do you create two recordings at the same time? The recording you innitiated and the one created by the timeshifting function?

I will try to use the pc monitor (21" CRT) and will post the results.

aucklander

478 posts

Ultimate Geek
+1 received by user: 11

#142421 3-Jul-2008 08:03

I also have a sat decoder connected to the TV through a dvd hdd recorder. I noticed there is no contrast change on the signal from the satellite, it only occurs on the signal from the htpc (live or recorded). The black level of the black bars on the sides, when watching satellite is very good, deep, nice black level with the sides perfectly contoured.

The black bars on the signal fed from HTPC are definetely "brighter" and some times there are two or three vertical bars next to the vertical side of the picture, where the black bars start (this could be a from a bad cable? - I tried both HDMI and RGB from the DVI output of the card, no difference). I watched the black bars when switching the source, after I covered the screen with a newspaper to avoid the eye being tricked by the screen luminosity. The black bars on the htpc signal are more like a greyish colour than black. Plus the ocasional luminosity increase (which I desribed before) which makes it worse.

I assume this is due to the resolution being set to 1360x768 on the nVidia card. This forces the card to send a signal to cover the sides of the image even when the image does not fill the whole 16:9 screen. Well, that signal does not appear to be "zero" or whatever code the black has. The nVidia control panel has an option to move the scaling on the TV, but that option does not stay selected, it is automaticaly reverted to "do scaling on the card" after I press OK button.

I have some other things to check, will post if any of them brings a change.

aucklander

478 posts

Ultimate Geek
+1 received by user: 11

#143552 7-Jul-2008 08:26

I focused on the troubleshooting of this thing during the weekend, and here is what I can say so far:

- it does it on live tv
- it is also visible on tv recorded shows (not sure if exactly at the same times).
- it does it on live tv and tv recorded shows, using DVI/HDMI or DVI/RGB cable to the TV.
- still does it on tv and recorded tv played through component (bad picture, anyway)
- I find the contrast change more visible during HD shows than SD shows, on any channel
- it does NOT do it when watching DVDs or HD sample clips stored on HDD or signal from other sources (I also have a sat decoder for freeview and the analogue aerial running through a HDD recorder).

The last one completely rules out the cables, the TV settings and the graphic card, right?.
The Tv has all the features which might generate such effect, turned off.

The only "fault" fitting in the above puzzle is the TV tuner !! I read a post about electromagnetic interference between tv tuner and PCI-e card, as they are so close. The 8600GT (silent) hetasink occupies the PCI slot next to it, so the Tv tuner goes into the other PCI (I have only two) but is still very close to the graphic card heatsink. I laminated aluminium foil and cut it to size to cover the tv tuner back and slide it in between but it did not change anything. I tried moving the cables (by hand), it is not from a bad cable or connection.

Could this be from the tv tuner?

Apple TV

Stream your favourite shows now on Apple TV (affiliate link).

1gkar

722 posts

Ultimate Geek

#143580 7-Jul-2008 09:21

I'm assuming when you say it does not do it using other sources, that means the picture is good when viewing TV through your DVB-S decoder (plugged directly into the TV & not through the HDD recorder) & watching SD with the aerial plugged directly into TV.

If that's the case, then it appears to be an issue with your HTPC. One reason I prefer full ATX is to separate my cards due to possible EM interference. I'm not saying this is the issue, as you have appeared to rule this out, but to elinimate any possibility.

You don't state what frontend you are using ie. Mediaportal, GBPVR, ETC.? If the former, does it happen with another frontend app?

Also, as we're to the desparate end of the scale, try changing to 'Video Mixing Render 9' inside Mediaportal configuration>Directshow Filter Controls>Video Renderer Settings (I'm assuming you're using EVR with Vista installed) & try that. Lastly, disable 'Use Exclusive Mode (aviods tearing...)'. I doubt they'll work, but you never know.

Finally, what codecs are you using? PowerDVD* for all TV formats? Does your Nova-T HD card playback in SD? if so, try another codec, like the pre-installed MPV codec, Nividia's Purevideo trial codec, or install Dscaler5 codecs. That's about all I can think of. Hope you rectify the issue. I know how annoying issues like these can be.

PS. is it an option to try the tuner card in another machine, it may have an issue.

aucklander

478 posts

Ultimate Geek
+1 received by user: 11

#143615 7-Jul-2008 10:10

I am using Media Portal. I also have Powercinema installed (it came with the Nova-T 500 HD card) but it doesn't work anymore after Media Portal was installed. I still have shows recorded with Powercinema and I tried to use it but it does not launch anymore. Should I really try and get it working?

I did change to VMR9 instead EVR and the picture quality is really bad. I switch it back to EVR immediately.
I will try the "disable 'Use Exclusive Mode (aviods tearing...)' ".

You asked a very intersting question: does my Nova-T card playback in SD ??? This never, ever, crossed my mind. On the other hand, maybe now is the moment to admit the image is badly pixelated if there is a requirement for gentle change of colour from one shade to another. Lets take for example any ad with the background trying to show a colour gradient. All I get is maybe 4-5 steps from center to the sides, each step made of the same colour, clearly separate concentric circles. Or maybe a large dark area, which instantly gets filled with "dancing squares", wroughly 1cm x 1cm !! I started to believe this is all I can get from my Bravia, and regreted I did NOT get a plasma, every time when this happens.

YOU ARE RIGHT!!! IT LOOKS LIKE SD !!! The best example (and easy to imagine by anyone) is the green screen before the movies, with the warning about innapropriate language, etc... that screen has only 4-5 shades of green from centre to the sides! I NEVER saw that as a continuous colour gradient.

I blamed this on the graphic card, but I could not find any setting to improve this. Except the colour, which is already set on 32 bits. I always asked myself why does it do it even during the HD shows? I know the ads are not HD, but it does this colour gradient thing even during the HD movies.

The CPU usage is around 40-45% with EVR selected (Vista SP1), which definetely shows something is wrong with the codecs... I used to get the same cpu load with Powercinema/onboard video/Vista... It dropped down to 12-17% with Powercinema/8600GT/Vista but I lost it after installing Media Portal, it went up to 40-45% and I could not bring it back.

So you are saying is could be the codecs causing this, and actually the hardware could all be OK?? This would be great. There is a "Vista HD codecs package" circulating on the net, free download, do you know anything about this? HDPack 1.4, .exe file, approx size 11.6Mb;

richms

29098 posts

Uber Geek
+1 received by user: 10207

Trusted

Lifetime subscriber

#143722 7-Jul-2008 12:57

Just a thought, but could it be the different black levels between PC and video causing it, since the PC may sometimes be outputting blacker then black as far as the tv is concerned, whereas the sat box etc are all normal video signals so never drop to 0

Richard rich.ms

1gkar

722 posts

Ultimate Geek

#143733 7-Jul-2008 13:15

To start: No, I don't know anything about the Vista HD pack, I use MCE2005.

What I was meaning about trying different codecs was to setup a new, or preinstalled (eg. MPV codec) in television of MP config & see if this helped with SD playback, in an attempt to localise the issue: HD-only or ALL television playback. Which is further info to establish where the problem actually lies.

Best to go into TV Server config & check if you have any SD (analogue tuners there) <TVServers>'host name'>. If you do, double-click to disable ALL DVB tuners, therefore setting the analogue one(s) at the top. Then try MP Live TV. You will be using the preferred (as setup inside MP config>television) MPEG-2 codec. Try this.

Also, with any of your *.ts HD record files, load them into a third party player like Zoomplayer (free download & playback for all but DVD). It should work out-of-the-box.

http://www.inmatrix.com/files/zoomplayer_download.shtml Just download the Pro version: it will work with a nag screen at loadup but is fully functional (at least it used to be)

Masterpiece

247 posts

Master Geek
+1 received by user: 37

#143897 7-Jul-2008 16:37

It could be possible for levels to change, however also if your display isnt calibrated it could quite possibly be clipping the signal.

If your display contrast is set to high you also could be clipping the signal.

Both these states cause perceptually changing levels.

What you could/can be seeing is higher intensity levels of screen luminance(average picture level), when ranging into the above condition you see crushed whites, washed out whites or higher contrast. ie detail in a white shirt washing out so no definition can be seen. As the avergae picture level drops and the white shirt is seen in dimmer conditions the detail returns.
A sign of clipping and crushing.

I have the exact same MB and happened to be evaluating the video output levels on the weekend in comparison to my video generator and the outputs are very safe so to speak.

Me:"I'm not a robot!"

ET: "Maybe; you have some freewill, but you chose your path by arrangement"

Me "That sounds like a program with no freewill?"

ET: "We will catch up when you end this cycle"

Me: "Sounds like a 'KPI'!"

ET: "Did you read the terms and conditions?"

Me: .....

Apple TV

Stream your favourite shows now on Apple TV (affiliate link).

aucklander

478 posts

Ultimate Geek
+1 received by user: 11

#148087 15-Jul-2008 14:12

How can I check if the pc outputs "blacker than black" signal?

All the troubleshooting I did (see earlier posts) pointed towards the tv tuner to be at fault, as it does it only on live and recorded tv. I replaced the tv tuner yesterday and... there is no improvement, it works exactly the same.

I did not do any adjustments of the video signal on the nVidia, I checked the "let my player adjust picture" option and I adjusted the picture from the TV menu only. I did use the adjustments on the nVidia at a certain point but I could not make the image look right, I did not like it (I got "crushed" colours). Should I still try and change the levels on the card, to avoid the clipping? (It used to do the contrast change even when the picture was adjusted on the card).

on the PC: If the image is 4:3 format, you have the black pillars on the sides. Well, if I look closely, the pillars are all pixelated, made of rather large blocks, dancing around. Is this normal? I mean... there is no signal, this is why you have the pillars, right? Then, why aren't they just black if there is no signal?

When watch tv through the aerial (straight into the tv), the side pillars have a very nice (deep) black colour, it looks like all those pixels are "off", exactly how they are supposed to be!

I replaced the tv tuner so far.
I will try to get the video card replaced as well.
The cable is a $25 hdmi cable, but everyone agrees that for the digital signal the cable quality is not a factor.

richms

29098 posts

Uber Geek
+1 received by user: 10207

Trusted

Lifetime subscriber

#148100 15-Jul-2008 14:35

Its an option in some codecs to expand the blacks, since video only works from 16 to 235, that gives crap blacks when viewed on a PC - the resulting decoded video is actually outside the norm for a video signal, but looks great on a PC. Sometimes this expansion of the blacks upsets LCD tvs, you really need to chuck up a grey graident from the PC and make sure you can see all the lower levels of grey, since they are outside the range normally used for video signals.

Richard rich.ms

aucklander

478 posts

Ultimate Geek
+1 received by user: 11

#148105 15-Jul-2008 14:55

I found something like this explained here:
http://www.audioholics.com/tweaks/calibrate-your-system/hdmi-black-levels-xvycc-rgb

How do I access options for various codecs? I set the codec I use in Media Portal by selecting it from a drop-down list, but that's pretty much all my contact with the codecs. I feel they have to allow you to set some parameters, but I do not know how to open such dialogue.

I used Cyberlink PDVD8 codec, I now use ArcSoft, both with same results, but ArcSoft gives me marginally lower cpu usage (30-40%, Cyberlink PDVD8 goes 40-50%, EVR enabled, I do not understand why I don't get the HA working...)

richms

29098 posts

Uber Geek
+1 received by user: 10207

Trusted

Lifetime subscriber

#148122 15-Jul-2008 15:17

I have usually had to do it in media player classic, which getting it to play using that codec is sometimes a challange in itself.

I think you can get to them in graph edit that comes with the directx tools. - Also FFDshow till make a tray icon that will appear that you can use to edit some of the codec settings in the graph.

Richard rich.ms

1 | 2