Nvidia interlaced custom resolution

[madhatter300871]

Hi all.

I have had recent success with using MadVR as my video renderer and have finally pretty much stopped tweaking my system. Video playback is great.

Except ......

Suddenly I am seeing some tearing in fast motion scenes, and I swear it wasn't there before. So I tweaked some more and spent many hours playing with many settings (I have a very good handle on what combinations of software do and don't work in my specific case, although I might not know why they do and don't work :)).

Anyway, I fixed the tearing in the end by setting another Nvidia custom resolution that is interlaced, in fact its 72Hz interlaced. Now when I play back any 23.976fps video there is no tearing what so ever (and also no panning-judder which is why I initially started playing with custom resolutions).

So my question is this :-

My video is progressive content, my custom resolution is 72Hz interlaced, my display 'info' panel shows a vertical refresh rate of 36Hz (half of 72Hz), and playback is smoooooooooth. Why would 72Hz interlaced not display tearing but 72Hz progressive would ? I mean the content is progressive (95% of the time) so how would playing it back in interlaced mode fix the tearing ?

Thanks.

[madhatter300871]

Any ideas, or anywhere I could look for more info ? I've searched here and on google but nothing so far.

[madhatter300871]

Scratch all that .... it's still not perfect on closer inspection (it was late !).

The only way I can get truly smooth playback is by speeding up to 25fps and outputing at 50Hz refresh rate, it's perfectly smooth. Reclock does not do a good job of keeping the audio in sync so I am now working on that.

Any ideas from anyone how to play 23.976fps video 100% smoothly in the UK ?

[mark0077]

By tearing do you mean say 1 big horizontal tear from time to time, or as in it actually looks interlaced?

I actually had an issue where playing back content on my Samsung Series 9 TV at anything other than 50hz, would actually exhibit a sort of interlaced effect now and again, and mostly depended on the motion. It was trying to do something smart no doubt, but wasn't doing a very good job at all and Samsung never solved it for me. I could actually stop it by enabling some of its motion interpolation functions but I didn't want to use them as for PC usage its horrible seeing the mouse go all weird from time to time (or even bring up the opaque brightness / contrast menu strangely).

So my solution was to use the perfect 50hz my TV displays, and I use avisynth / svp scripts to interpolate all of my content to 50hz before sending to TV. So basically, it was my TV that was adding this effect at anything other than 50hz and not the PC.

[madhatter300871]

Hi, thanks for the reply.

No, its not an interlaced source and its not interlacing artefacts. Its definitely tearing, the top half of the picture being offset from the bottom half, a little, sometimes on fast moving scenes. Its one big horizontal tear.

Tearing disappears when I output at 50hz or 60hz, but then I have judder (particularly noticeable on slow panning scenes).

I too have had great results speeding my video up to 25fps and displaying it at 50Hz. Smooth as cashmere !! lol

However, I just find it hard to believe that UK blurays are usually, on the whole, at a frame rate of 23.976 and yet our TVs (projectors, whatever) accept 50Hz and 60Hz input. So, the player or the TV must be telecining mustn't it ? How is that good, why aren't blurays just at a frame rate of 25fps like DVDs ?

If the TV can accept 24p, well my question is - is this really 24p, or 23.976p. The same dilema remains, frame rate is not an exact multiple of refresh rate and so judder will occur. Its driving me round the bend !!

[madhatter300871]

Thought I would wrap this up for anyone interested. I found out the answer to my problem, UK blurays are indeed NOT natively compatible with all UK displays (be it TV, projector or whatever).

Thanks Hollywood !!

Was quite a battle but got there in the end.

[dukey]

set the refresh rate to the highest value possible
that'll eliminate most of your problems

[Ghitulescu]

If the TV can accept 24p, well my question is - is this really 24p, or 23.976p. The same dilema remains, frame rate is not an exact multiple of refresh rate and so judder will occur. Its driving me round the bend !!

It's irrelevant, the PLL in TV should lock on 23.976 as well (~0.1% less :)).

[Ghitulescu]

I found out the answer to my problem, UK blurays are indeed NOT natively compatible with all UK displays (be it TV, projector or whatever).
No, any player should match any display. The decision which format is accepted is a political/economical one not technical (eg Pioneer dropped two years ago the support for 720p, except for native 720p materials, to favour 1080p).
There is no fps problem with any blu-ray player, but if there is a playback problem then it's mostly related to how well can it deinterlace/IVTC the material (for DVDs or 1080i live video material).

I think you should rephrase your statement: Thank you IBM/Microsoft/WarnerBros for playback issues on a PC.

[madhatter300871]

OK. Happy that decisions are made for political ends not technical ends, perhaps your right, i'm still a little confused here and still testing. Not sure I should say "Thank you IBM/Microsoft/WarnerBros for playback issues on a PC." The PC playback is flawless, the problem is getting it to not judder on my PJ.

Dukey, setting my display to the highest refresh rate available is not the correct solution as I tried to describe. Doesn't eliminate most of my problems.

It appears my projector only support 50Hz/60Hz so I just set the MKV framerate to 25fps and re-encode the audio to HQ AC3, I'm very happy with the results.

The problem seems to be my display (Sanyo Z4, yes I know its old), the PC handles everything i throw at it and plays it back just fine. Its not the PC casing the judder and de-sync per say, its the inability of the PJ to accept the refresh rate I want to give it.

Hope that makes sense !

[Ghitulescu]

Because your computer is connected to a computer display (or any panel that mimics one), and thus outside of the TV/audio/video world. To which world your projector belongs. You can try to use the PC input of it (which will accept non-standard resolutions or fps, ie those used in a computer like 1366x768x72) but AFAIK this needs a VGA (thus analog) connection, and VGA is blurred (actually it's not blurred but it's clipped in the higher part of the spectrum, with the obvious consequence of loosing the fine details).

You confirm what I said. You can't force the projector to accept non-standard (ie computer signals) using its regular A/V-inputs. You have to thank Warner and M$ for this.

[hello_hello]

Reclock.... so far at least... seems to have fixed the tearing I was experiencing. I wasn't experiencing dropped frames or anything like that, just occasional tearing. After a while I discovered it happened more often when upscaling 480p content, especially PAL video as my PC is connected to the display at 60Hz. I'm using the video card for h264 decoding but it seemed to be the same for Xvid too.
After a bit of experimenting I discovered changing the resizer from Bicubic to Bilinear eliminated the tearing problem. Maybe because it requires less computing power. Not quite as sharp when upscaling but at my normal viewing position I couldn't really see much difference. Later on I tried Reclock again and changed the resizer back to Bicubic. So far the tearing problem doesn't seem to have returned.

Anyway, if you aren't using Reclock, give it a try. It seems to have fixed my tearing problem and according to Reclock my video card's refresh rate was only off by 0.001Hz (at 60hz). If nothing else, it can be set to automatically play 24fps content at 25fps, so if your setup currently plays 25fps video without tearing, you could use reclock to play everything as "PAL".
Unless you tell it otherwise, Reclock will also convert 23.976fps video to 24fps, so if you're connected via a PC input at exactly 60hz it might also help that way.

[hello_hello]

Well, it looks like I lied. Reclock definitely improved the tearing problem, but I just noticed it happen while I was watching a video, so it didn't fix it. It looks like it's back to a Bilinear resizer for me as doing so certainly seems to get rid of it. Maybe I just need a better video card? I'd be interested to know exactly why one resizer is fine but the other causes tearing. I can use any resizer when displaying video on the PC monitor without tearing, so it must relate to the resolution and the amount of upscaling. My PC monitor isn't running anywhere near 1080p as the TV does.