Purevideo Video decoder issue

[clmolnar]

I recently built a new HTPC, and it has been experiencing problems while replaying recorded TV shows with Nvidia purevideo decoders.

The best way I can describe it is every 5-10 seconds, I get a glitch in video playback. It's not a stutter, nowhere near as bad, although it is noticeable. It's almost like a single frame is being played back at some offset to where it should be. Switching to the SageTV decoder fixes the problem, however the overall playback quality is reduced.

I have tried version 185 and 223 of the Purevideo decoder, and experience the same problem with both versions. I am using forceware 91.47 for my 7600GT.

Other system specs:

Intel Core 2 Duo E6600
Asus P5B-VM mobo
1Gig PC800 ram
XFX 7600GT (forceware 91.47)
Hauppauge PVR-500
Windows MCE 2005 with all updates

This is a minimal windows install, with only SageTV and drivers installed over MCE 2005.

Has anyone had any problem like this before or have any idea what I might need to do to fix it?

Thanks,
Carl

[clmolnar]

Ok, I was able to fix this by changing the from "Smart" deinterlacing to "Automatic". However, I remember reading somewhere about a problem with "Smart" deinterlacing and how to fix it, since the "Smart" setting is better than the others.

Does anyone remember this?

Thanks again,
Carl

[blade]

As far as I know there is no fix for it. I don't think anyone even knows what causes it. Last I checked no one had been able to establish a pattern. It seems to occur at random with various hardware and software combinations. I know from personal experience that many of my shows playback perfectly using the smart setting and some are almost unwatchable. For others using the same video card, decoder, driver, etc... they never experience the problem.

I don't know how familiar you are with the Nvidia decoder so I'll explain it to the best of my ability. If you use automatic you will not get proper deinterlacing on your recordings. Automatic reads how the content is flagged to determine if it is film or video. The content is handled differently depending on which it is. All of your recordings are going to be treated as "video" so they will be deinterlaced and playback back at 60 fps.

The problem is the majority of content is actually film (24 fps) that has been telecined. So it will not be handled correctly by the decoder when using automatic. When using smart mode the decoder doesn't go by the flag and determines for itself which method to use. It will properly playback the telecined recordings at 24 fps.

I've noticed the bug doesn't appear if I use Nvidia Post Processing (software mode). I usually just leave mine set to smart and if I run across a particularly bad show I switch to software mode. Of course if the majority of your shows do this then it's not really an option.

[Polypro]

"Smart" has never worked for me. From my limited understanding, "Smart" analyzed the actual frames, where "Automatic" just obeys the flags. Now I don't know the frequency of badly flagged content, but 84.25 Drivers with .185 decoders on "Automatic" are what I run, and it looks good.

P

Edit: Blade, I'm stalking you (Post Times).

[blade]

Originally Posted by Polypro

Now I don't know the frequency of badly flagged content, but 84.25 Drivers with .185 decoders on "Automatic" are what I run, and it looks good.

I have no clue about HD, but with SD analog capture cards everything will be treated as video. Just guessing I'd say +95% will be telecined and treated incorrectly. I noticed MI5 and Married with Children are treated as video when using Smart. All of my remaining +75 favorites are film that have been telecined.

To me using automatic doesn't look that bad, but it doesn't look as good. On a smaller screen I probably wouldn't notice it as much though.

If you're the curious type and run VMR9 install FRAPS. It will show 24 or 60 fps when using Smart depending on the content. Makes it easy to see how much content is actually film.

Edit: Blade, I'm stalking you (Post Times).

[IncredibleHat]

I get mixed results, with most of the 'better' shows (1hr dramas it seems) to do the flicker randomly.

No idea why, no pattern to it. Some shows just seem fine througout, and some keep flickering everytime the scene changes, or the camera angle switches quickly. It's mighty annoying, and actually makes me feel like I have a twitch in my eye.

So, I run automatic, and just accept the quality. At least its consistent, and not throwing my brain into tizzies

[Patilan]

@clmolnar:
You may want to try the PureVideo™ HD BETA drivers. I am currently running version 92.91, and my system is very stable. Give it a try if you want.

-=Patilan=-

[IncredibleHat]

I'm using 92.91, and thats not 'purevideo', thats forceware. Plus I still get the problem.

It is a completely hit or miss scenario. One persons "works fine" is not what another person will get.

[blade]

Originally Posted by IncredibleHat

I'm using 92.91, and thats not 'purevideo', thats forceware. Plus I still get the problem.

Patilan is correct. If you look on the Nvidia site they refer to the driver as PureVideo HD Beta Driver. Purevideo is a marketing term that covers a wide array of technology. It is not limited to just the decoder.

[clmolnar]

Originally Posted by IncredibleHat

I get mixed results, with most of the 'better' shows (1hr dramas it seems) to do the flicker randomly.

No idea why, no pattern to it. Some shows just seem fine througout, and some keep flickering everytime the scene changes, or the camera angle switches quickly. It's mighty annoying, and actually makes me feel like I have a twitch in my eye.

So, I run automatic, and just accept the quality. At least its consistent, and not throwing my brain into tizzies

Thats exactly what is happening with my box. The 1-hour shows are the ones that have the flicker problem. My 30 minute comedies (Seinfeld, etc) don't have the problem.

It really kills me to watch LOST with the flicker, but I'm not sure if the flicker or the reduced picture quality is worse.

[asthepenguinfly]

I have this problem as well. The flicker is amazingly annoying. I get it a lot during the daily show/colbert report. The heads moving on backgrounds and camera angle changes make me nearly insane. Lowering saturation seems to help, but I don't know why.

[blade]

When I've brought this up in the past in other forums people have argued that this isn't the problem and is normal, but I'll explain what I have observed anyway. If someone with the problem doesn't believe it they can install FRAPS and verify for themselves. Those that don't have the problem have no real clue what we're talking about anyway so it doesn't matter if they believe it or not.

Many older shows such as Married with Children (maybe Seinfield I don't watch it so I'm not sure) are entirely video. I don't believe I have ever experienced the "flicker" problem with video content if so it hasn't been often enough for me to remember.

Most newer shows are film and some are a mix of the two. For example SG1 is film, but sometimes a special effects scene such as a space battle will be video (it has been a few months but I'm pretty sure SG1 is the show I noticed this on). The decoder switches perfectly for me between the two types of content and there is no flicker.

It is normal for the decoder to sometimes switch between film and video while playing back a show and this shouldn't cause a problem; however, I noticed over a year ago that the frame being played out of order seems to occur when the decoder is excessively (every few seconds) switching between flim and video. For example the actors are sitting there talking and the decoder is jumping back and forth between 24 and 60 fps. I've had people try and tell me this is normal and I say it is not. When there is no scene change or cut shots I see no reason the decoder should be switching between film and video.

If you use FRAPS and have the problem you can see exactly what I'm talking about. When a show plays back at a stable 24 or 60 fps you'll rarely if ever see the problem. When the problem does occur I'd be willing to bet you'll see a jump in the frame rate and most likely it will be a very unstable show (switching a lot throughout the entire show).

I have no idea how Nvidia determines if content is film or video, but it would seem to make sense that certain factors could improve or worsen detection. I've contacted Nvidia in the past to see if there is anything I could do to my captures or decoder to improve detection, but of course never got any response at all.

When using Nvidia Post Processing the frame rate for the same show is still unstable and jumps from 24-30 fps (max that software mode does), but the problem doesn't occur.

Of course all of this is just my experience and I haven't noticed it on my other client, but I don't normally watch the shows that tend to give problems on it. When I get time I'm going to try and really compare the two.

[IncredibleHat]

Maybe the worse one's cable is, the more possible the chance of the instable 'smart' switches. I know my analog cable is the craps, because it starts to mess with the hauppauge cards themselves when trying to tune.

Maybe if/when I go to dish, this problem may ease up ? Or are you on dish already and notice the problems a lot ?

[blade]

Originally Posted by IncredibleHat

Maybe the worse one's cable is, the more possible the chance of the instable 'smart' switches. I know my analog cable is the craps, because it starts to mess with the hauppauge cards themselves when trying to tune.

Maybe if/when I go to dish, this problem may ease up ? Or are you on dish already and notice the problems a lot ?

I'm on analog cable and have thought the same thing, but have never been able to test it. I would think having a cleaner capture would allow the decoder to more easily detect the type of content, but I have no clue if it actually does. The only thing that makes me question this is that I used to have a terrible time with shows from USA and TNT which are two of the clearest channels I get.

[ben_95sl1]

I have had the same problem occur on every recording I've looked at on two different machines....it is VERY annoying. I cannot use smart deinterlacing because of it...however, I can't remeber what happens on DVDs and smart enabled? I actually find vmr9 and purevideo on my 6150 to be quite soft on recorded material compared to my older ati overlay with purevideo setup. So far my old ati 8500 in overlay was actually better then the renowned VMR9 + Purevideo decoder + Nvidia hardware.

[sundansx]

Originally Posted by clmolnar

Ok, I was able to fix this by changing the from "Smart" deinterlacing to "Automatic". However, I remember reading somewhere about a problem with "Smart" deinterlacing and how to fix it, since the "Smart" setting is better than the others.

Does anyone remember this?

Thanks again,
Carl

clmolnar,
What version of the purevideo DECODER did you end up with that this fix worked on? I am having the same problem with my new system using an 8500gt.
thanks.

[Thraxius]

From what I have heard this is a known error. It is something to do with the buffer and it shows a scence or screen from a few secs before. Only happens with interlacing.

Also from what I have read it is fixed if you use Vista. So Nvidia is not going to be fixing the error on XP. That is all I know about it.

[KryptoNyte]

Can you nVidia guys tell me if the Purevideo decoders are simply part of the software you receive or download for your nVidia video cards, or have you all purchased the Purevideo Decoder software from the nVidia site?

[clmolnar]

Originally Posted by sundansx

clmolnar,
What version of the purevideo DECODER did you end up with that this fix worked on? I am having the same problem with my new system using an 8500gt.
thanks.

I am using the newest version, I believe it is 223. Unfortunately, I still see this problem on certain channels, so switching to "automatic" was clearly not a complete fix. Sorry!

Carl