General video bandings problems

[cyberderf]

I have general video bandings problems on my system, which consist of a Athlon 1.4 Ghz, more than 600 mbytes or ram, a GF4 MX 460 and a 7200 RPM HD. The CPU occupation is very low and everything seems weel configurated over my hardware.

I am experiencing horizontal bandings over almots any vodeo file, including mpeg and DivX. Those bandings appears into camera movements (travellings) and action sequences of any vido clip.

I have used DivX 3.11 Alpha, 5.01 and 5.02. I tried with several differents players like BSplay, Zoom Player and the core Media player 6.4. It seems that nothing can eleminate these annoyings horizontal stripes. Please help me GUYS !!!

[Awatef]

This has nothing to do with your hardware, your movies were encoded without having been deinterlaced.

For your next rips, don't forget to deinterlace or IVTC ;)

[cyberderf]

HUm.. Thanks for input but i'm not sure it is the problem here.

All the movie i watched are from great sources, if u know what i mean =)

[Swede]

Well, great or not, it could still be interlacing that's your problem. Take a look at this site (http://www.100fps.com/) and come back if this is not the case.

[cyberderf]

Well, thanks for the input it seem like it's not the case.

I think it is possible that my problem is common to everyone. Do you guys get some hozizontal lines (a couple of lines) that cut the image when there's ''cam travelling'' or fast action scenes ? Is this problem called ''horizontal bandings'' ?

[Awatef]

@ cyberderf
I'm pretty sure they are interlacing lines!
Why don't you attach a screenshot, so we can confirm that they are interlacing lines and that you have to deinterlace if you wanna get rid of them?

[cyberderf]

Well, it's a great idea. Look at this one. The banding probleme appears in the upper area (look on the pink logo on the hat)
http://www.pbase.com/image/2685833/original

There's also this one that illustrate the same typical issue (look at the arm)

http://www.pbase.com/image/2686096/original

[avih]

just run a quick test to confirm my observation:
advance the clip frame by frame (in zoom player or in virtual dub). you should not see the problem anymore for any single frame. is that correct?

if it is the case then what u have here is a vertical sync playback problem. it happens when the image 'switches' to the next one while the monitor beam is in the middle of the 'refresh' cycle.

so if your player has a 'vsync' checkbox, use it and your problem should disappear. it may also be controlled from the display driver configuration (force vsync or use vsync).

but then youre clip might not be smooth anymore.

imagine the next scenario: let's say your clip is 24 fps, and your monitor refresh rate is 60Hz (just for the case of this example). so your monitor displays exactly 60 images a second, but your clip is 24, and 60/24 is NOT an integer, so sometime an image will stay on the monitor for 3 refresh cycles, and sometimes for 2 of them. so the playback isn't smooth.

the best thing you can do about that is set the refresh rate of the monitor to a multiple of the clip fps. if possible of course.

cheers
avi

[evilhomer]

don't forget to make sure your video is a multiple of 16 in width and height. some video cards have a problem with overlay if not and that could result in "banding."

also, try a different playback filter.

[Awatef]

well, seems like these are not interlacing lines after all :D