Deinterlacing SD cartoons

[AndersB]

I am using the NVidia Purevideo decoder to decode MPEG2 material in DVBViewer and everything looks fine expect when the kids start watching cartoons on any of the SD channels. Then, especially fast moving scenes, the moving objects get really blurred just like ordinary blend deinterlacing would be used. In the Nvidia decoder I've tried all combinations of deinterlacing settings without any improvement. As I said, this problem is only occuring when watching animated material - at least there is where it's visible. Anyone have any clue on what might be the reason and how to fix this?

[Moses]

I don't think that this is related to deinterlacing. I think it's the issue that mpeg2 is not realy suited for cartoons and that most of the cartoon channels offer only a very low bitrate.

[AndersB]

I don't think that this is related to deinterlacing. I think it's the issue that mpeg2 is not realy suited for cartoons and that most of the cartoon channels offer only a very low bitrate.

 

Ok. Forgot to mention that it's also visible in the scrolling credits after a movie (still TV material). Don't know if they are caused by the same problem as they use the same decoder. I mean, my set-top box is capable of showing this without the annoying "ghosting" so there must be something in the deinterlacing or something else in my HTPC configuration. Just can't figure out what.

[dvbrewer]

Ok. Forgot to mention that it's also visible in the scrolling credits after a movie (still TV material). Don't know if they are caused by the same problem as they use the same decoder. I mean, my set-top box is capable of showing this without the annoying "ghosting" so there must be something in the deinterlacing or something else in my HTPC configuration. Just can't figure out what.

Try using ffdshow instead.

[RichardWhite]

It's hard to say without being able to see the problem, of course, but this is actually very likely to be caused by a combination of how many cartoons are converted for PAL broadcast and PureVideo's methods of dealing with such hybrid material. I won't bore you with all the specifics, but due to crappy conversions, you do essentially end up with blurred images in the broadcast source that look just like regular blend deinterlacing. This is something deinterlacing filters have struggled with for years, and it becomes far more apparent when watching on a progressive display as opposed to an interlaced one, and cartoons in particular tend to highlight the problem of poor conversions like that. If it happens on all cartoons and scrolling credits, it's probably something else, though. What are your exact PureVideo settings?

[AndersB]

It's hard to say without being able to see the problem, of course, but this is actually very likely to be caused by a combination of how many cartoons are converted for PAL broadcast and PureVideo's methods of dealing with such hybrid material. I won't bore you with all the specifics, but due to crappy conversions, you do essentially end up with blurred images in the broadcast source that look just like regular blend deinterlacing. This is something deinterlacing filters have struggled with for years, and it becomes far more apparent when watching on a progressive display as opposed to an interlaced one, and cartoons in particular tend to highlight the problem of poor conversions like that. If it happens on all cartoons and scrolling credits, it's probably something else, though. What are your exact PureVideo settings?

 

Thanks for that answer. Of course it's not for all animated material but for some, noticed it especially on some old Disney material aired on some channels. My purevideo settings are automatic deinterlacing control and software Best Available (bob or weave) deinterlacing, hardware acceleration is disabled.

 

So I guess the reason why I see this on my HTPC and not on the STB is that the HTPC is connected to my Plasma display (progressive) and the STB is connected to my old CRT set, rather than due to the HTPC versus STB itself and then I've to live with it.

 

I recorded some of this material to decode it on my other PC using ffshows different deinterlacing methods and there was some improvement in using motion compensation deinterlacing but still blurry.

[RichardWhite]

Thanks for that answer. Of course it's not for all animated material but for some, noticed it especially on some old Disney material aired on some channels.

Old Disney toons are known for having the problems I mentioned. It also happens in some movies, but due to the complexity of live action images, it won't be very noticeable until you get to... you guessed it; the credits.

 

So I guess the reason why I see this on my HTPC and not on the STB is that the HTPC is connected to my Plasma display (progressive) and the STB is connected to my old CRT set, rather than due to the HTPC versus STB itself and then I've to live with it.

Yes, the problem is that this method was designed to take advantage of interlacing to hide the flaws. Problem is, modern TFT and Plasma sets are no interlaced, so they really show the flaws of such material.

 

I've attached an example to show you what I was talking about. These are two frames from an Inspector Gadget cartoon. I've unfolded the fields, and as you can see, there are blended frames in the source material itself. They're limited to every other field, so they'd barely be noticeable on an interlaced CRT set.

 

 

I recorded some of this material to decode it on my other PC using ffshows different deinterlacing methods and there was some improvement in using motion compensation deinterlacing but still blurry.

Makes sense. Like I said, there have been many different attempts at dealing with this sort of hybrid material, so you're likely to get different results with different methods, but unfortunately, there's no perfect way to deal with it. In the PureVideo settings, try setting the Deinterlace Mode to Display Fields Seperately. It's probably the best way to deal with such material.

 

Btw, any reason you have hardware acceleration off?

[AndersB]

Thanks Richard, those screens really show exactly the issue I am referring to. Thank You for clarifying - now I don't have to invest any more time troubleshooting this. Regarding DXVA, I've found that when I enable it (tested on both integretade GeForce 6500 and a GeForce GTX260) I get a lot of jagged edges and stuttering playback. When I disable DXVA, I get silksmooth playback and a great-looking picture. As my CPU has no problem decoding both SD and HD material I didn't bother with hardware accel.