Tearing Test - Vertical Line does not pan smoothly

[jmone]

Another Newbie Q - When I do do the tearing test should the vertical line appear to move smoothly across the screen or be more two alternating vertical visible lines? It is hard to describe correctly but it is not a broken line vertically (eg from tearing), its just not a smooth single line moving across the screen (but f I pause it is one solid line).

I had a play with the VSYNC and I don't think I have any of these related issues. I also see the same effect at 50hz with PAL material & 24hz with Blu-ray disks. Is this "normal" or an indication of other things to start tweaking!

Thanks
Nathan

[theshadowrunner]

Hi,
The tearing test line should move as smoothly as possible across the screen, each new drawing of the line corresponds to a new frame of the movie being displayed.
There shouldn't be any tearing, nor should the line appear to be "jumpy" (which can sometimes occur due to microsoft's vsync implementation in directshow).
You should be seeing a huge difference during the tearing test when a movie is played at 60hz (line stuttering) versus when it is played at 24hz (line perfectly smooth).
To give you an idea, try the tearing test with Ntsc contents (29.97fps) and the screen set to 60hz, the line goes fast across the screen and smooth. Cinema contents with screen set to 24hz should have the tearing test line go across the screen much slower, but just as smooth.
See you,

TSR

[jmone]

Hi,
I notice that the line changes in size and speed based the overall resolutions settings with 1920x1080x24 being a fine line moving more slowly than PAL 576i material for example. However regardless of the format I still see the "two alternating lines" move across the screen. I've tried different video renderers but it is the same.
Thanks
Nathan

[noee]

Have you tried pausing and resuming to see if that gets rid of the tearing?

[jmone]

Hi noee - thanks but what i'm seeing is not tearing. The vertical line is unbroken but what I "think" I'm seeing is almost two seperate vertical lines slightly out of phase.
Thanks
Nathan

[theshadowrunner]

hmm actually, do you use ReClock's RunEvent script to change the display resolution according to media?
roughly it should be:
ntsc-> 60hz
cinema -> 24hz
pal -> 50hz
If you do use Runevent, can you actually see a difference in the line behavior when you're playing Cinema with display at 24hz and Cinema with display at 60?
Later,

TSR

[jmone]

Yup I syncing Cinema to 24, PAL to 50 and NTSC to 60. Cinema at 60 has the same effect. The effect is worse if there is a mismatch (eg Cinema at 50). I did get a perfect smooth line running Cinema at 2x speed (but had Green trailing and Blue leading edge) which makes me think this is "normal" for interlaced material. The only problem is it is the same effect for Progressive Material (both 720p and 1080p).

Next thought was it may be a setting in the TV - I've a Pio Kuro LX608a (Elite in the US) and I've had it professionally ISF Calibrated - tried a few setting changes but it still was the same.

Maybe I'm being picky? but I do notice it on pans...

Thanks
Nathan

[HaDeCzech]

Hi Nathan,

I think I have the same problem as you. When I run tearing test in ReClock I can see that the running vertical line is more like two quickly blinking lines next to each other instead of one solid white line.
When I pause a movie the line is straight (unbroken).
I can see that the problem affects fast pans in movies - edges are blured and an image loses details. When I pause a panning scene the image is crystal clear without double or blurred edges.

I have no idea if it is normal behavior of 24p technology (quite low framerate) or if there is a bug in my video playback.

Have you found any solution?

Thanks
Petr

My SW:
WinXP Pro SP3, Media Player Classic 6.4.9.0 - Mod Casimir 666 v1.0.10.0, Ati Catalyst 9.1

My HW:
C2D E8400, Ati Radeon 3650 => dvi->hdmi adapter => HDMI-HDMI cable => Samsung PS42A457 (plasma screen)

[theshadowrunner]

Are you guys sure that your display *runs* at 24fps?
Some screens *accept* 24fps on their input but convert internally.
Scandalous marketing trick btw.
Later,

TSR

[HaDeCzech]

Hi TSR,

it occurred to me too but I don't know how to check this. Any ideas?

When I press the INFO button on my remote control my TV shows "1920x1080@24 Hz" but as you suggest it means nothing and maybe it only shows what the input signal is.

Thank
Petr

[theshadowrunner]

Sure, compare CINEMA @ 24hz to CINEMA @ 60hz on your screen with the tearing test.
If they're similar, there's internal (24 to 60) retreatment.
If 24Hz is definitely smoother, the screen is most likely doing 24Hz.
Later,

TSR

[Mark_A_W]

Another Newbie Q - When I do do the tearing test should the vertical line appear to move smoothly across the screen or be more two alternating vertical visible lines? It is hard to describe correctly but it is not a broken line vertically (eg from tearing), its just not a smooth single line moving across the screen (but f I pause it is one solid line).

I had a play with the VSYNC and I don't think I have any of these related issues. I also see the same effect at 50hz with PAL material & 24hz with Blu-ray disks. Is this "normal" or an indication of other things to start tweaking!

Thanks
Nathan


It's pretty common to see what looks almost like 2 lines that squiggle together.

I found that moving to vista gave me less squiggle - along with smoothness I aim for the least "squiggle", as I think that reveals jitter in the frame delivery.

[Bitmonster]

You are actually seeing a "visual illusion". If you display the same picture multiple times with a small black pause between them (like all CRT displays are doing it) before moving to the next frame, your brain tries to interpolate a picture between the frames. If your display is set to 50Hz the tearing bar is only moved every second display refresh (as the media frame rate is only 25fps and not 50fps) and the brain gives you the illusion of two separate bars.

If you pause the movie and do single frame advance, you would see that the tearing bar is really only a single bar.

On sample-and-hold display types (like LCD/TFT) you would see this effect as a kind of smearing. This is one reason why TV manufacturers try to build displays with frame interpolation (120Hz LCDs).

The same phenomenon you can see also in real movies and cinemas, because there the movie is also displayed with 48Hz. If the camera is panning or some objects are moving fast, you can see some kind of doubled contour on them. The faster this moving is, the more obvious this gets. That's why filmmakers avoid panning too fast in movies. Again on sample-and-hold displays this effect looks more like a blur and people start to talk about "motion blur", but this is not the right term. Real motion blur is the result of the shutter speed of the camera, but this double contour effect has more to do with temporal-aliasing and stroboscopic effects.

The only real way to avoid this, would be to make films with 48fps or more. But Hollywood regards this as too expensive.

@Mark_A_W
If you are seeing this effect more smeared on your CRT under Vista, then Vista is actually doing bad things like blending frames.

[Mark_A_W]

No, I get a smaller squiggle in the line in Vista. Vista is better.

I think it's because there is less JITTER.

Vista or XP can't "blend frames" as I only use ZP or MPC-HC in software mode. Vista does seem a touch better in regards to the squiggle and tearing (not a huge problem in XP, but in Vista it won't tear no matter what renderer I use).

[Bitmonster]

No, I get a smaller squiggle in the line in Vista. Vista is better.

I think it's because there is less JITTER.

Vista or XP can't "blend frames" as I only use ZP or MPC-HC in software mode. Vista does seem a touch better in regards to the squiggle and tearing (not a huge problem in XP, but in Vista it won't tear no matter what renderer I use).

I don't really understand, what you are saying.

If there would be any jitter in the frame delivery, it would easily be identifiable as judder with the tearing bar. And obviously there is no judder in XP (if the system is setup right). So if you see a difference of the tearing bar in Vista compared to XP, you actually see something that is not right. XP definitely shows it right.

Or are you are talking about "tearing" solely?

[Mark_A_W]

No I'm really talking about the fact that the line looks like 2 lines that squiggle together.


Not coarse judder - closer to what Vern Dias used to call Micro Judder.

[Seeco]

This is great, I have been seeing this problem for a long time but this is the first time I have actually read about someone who sees the same thing. I'm not insane! :)

What I am seeing - instead of one solid horisontally moving line, there are two alternating, "blinking" lines. Their movement together is pretty smooth even in 24Hz mode, but the effect on video is that for example sharp vertical edges between light and dark objects also "flicker" during pans. It looks exactly as with the vsync lines, the edges of objects seem to blink and double. This is not the same as ghosting which is a smoother trailing of edges. While panning is smooth, this blinking gives a very funky impression and is quite tiresome to the eyes. In darker scenes (with low contrast) it is far less noticeable.

My TV is a Pioneer 5080XA, and I now for a fact that it can display 24p material at a multiple of 24 (72Hz I think).

Sounds good that the problem is smaller with Vista (EVR presumably), but I'm still hesitant about changing from XP.

[hagayg]

Try using avisynth + ffdshow to dobule or triple your framerate and you'll see the line very smooth (also the movie)

use :

ChangeFps(Framerate*2)

or

convertFps(Framerate*2)

(if your refreshrate is double than the frame rate use the aboive other wise multiple as needed - Framerate*3 for 24fps on 72hz monitor)

The first one just causes the player to output same frames the second one creates a new blending frames which generates a really smooth (but somewhat blurry image)

with both options you'll should be able to see a smooth tearing line

Hagay

[Seeco]

Well, I use the 24Hz refresh rate which is predefined in CCC, so what does that mean for this frame-doubler-thing? The TV triples this to 72Hz as far as I know.

[jmone]

To my understanding if you are using a TV you will have the defined frequencies of 24/50/60. While a PC may handle 72hz (or others) you can not output to a TV at this frequences. A TV may internally then increase it's processing from 24 to 48 or 72 hz etc by frame doubling/trippling or by using interpolation but at which point the HTPC has already output the stream at 24hz (so the "two line" will always be present).
Thanks
Nathan

[Seeco]

So the TV should be doing the thing that this AVISynth script does? Anyway, I tried the script but it only resulted in severe stuttering, either it just didn't work very well with my setup in general or it overloaded my CPU.

[jmone]

Not really as the PC will first read a file then render say 24 frames transmit to the TV that will then read the 24 frames and make say 72 so any issues with the first 24 frames (eg the squiggly line / judder / tearing / jitter will still be present no matter how many additional frames are created by the TV).

There is an argument that many of this issues are visually reduced if the PC can read the file's the render and display at higher frequences in one pass (eg 72hz). This would (currently) only apply to PC Monitors.