Can vertical oscillation be fixed?

[davexnet]

Hello,
Not sure what the correct term is, but it's apparent when playng the DVD on the TV.
A kind of up and down (perhaps one line?) flickering.

I've seen it before, but really noticed it when converting a recent avi to dvd.
If I play the avi on the TV directly in the standalone player, it's rock solid.

If I convert the avi to mpeg2 > dvd, the problem appears.
The avi is progressive, 25 fps and I'm converting to 25 fps 720*480 then doing
DGPulldown 25>29.97.

The avi is unusual in the sense that it's 720*576, but has 100 pixels top and bottom of black.
The remaining picture in the middle is 1:1 when viewed in virtualdub.

So far, I've converted it in AVStoDVD (but with a modified avisynth script to deal with the big black space)
and I did a manual encode in Tmpgenc 2.5 - the results were equally problematic.

Any ideas about this phenomenon appreciated.

[_MrC_]

Are you sure the source AVI is progressive? What do GSpot/Mediainfo say?

Using AVStoDVD, did you try both HCenc and QuEnc?

A trial without cropping the black bars could be useful.



Bye

[jagabo]

If you are watching on an interlaced TV (CRT) the sharp horizontal line between the image and the black borders will bounce up and down by one scan line, 25 times a second. Especially when the contrast is very high. You must soften the edge to reduce the bounce/flicker.

[davexnet]

Hi MrC - I'll try the encode without cropping, but I think it gets the aspect ratio wrong.
I'll do it this morning and report back. Here's the info from Gspot.

jagabo, regarding the interlaced TV. It is a 27 inch Panasonic CRT TV I'm viewing it on from 2004.
I *believe* that this TV has a progressive scan doubler. Not sure if that affects things.
Secondly, the "effect" I'm talking about is visible throughout the picture, not just bottom/top edge.
It looks far worse on moving scenes.

[jagabo]

the "effect" I'm talking about is visible throughout the picture, not just bottom/top edge. It looks far worse on moving scenes.

Interlace bounce/flicker can happen anywhere there are sharp horizontal edges. But since you say it's worse with moving scenes I suspect that is not the problem.

Your AVI file properties don't look unusual at all. Maybe you should post a short sample from the DVD. A sample where the problem is most obvious. You can use DgIndex to make a short clip.

[davexnet]

Unfortunately I don't have the original DVD.

However, I processed the existing avi another way and got a successful
result. I frameserved it at 23.976 (it's originally 25fps), encoded
it in HCenc and allowed the encoder to do the pulldown. The result is
perfect. (however, now I need to stretch the audio !)

Doing it the other way 25fps, 720*480, DGpulldown 25 > 29.97 was terrible. << something bad about this process ?

[jagabo]

Doing it the other way 25fps, 720*480, DGpulldown 25 > 29.97 was terrible. << something bad about this process ?

I do it without problems. Must be your DVD player and/or TV.

[davexnet]

It may be the TV, or something peculiar about the avi source.

I tried MrC's suggestion and ran it through AVStoDVD "as-is" (no cropping).
The result looked fine on the computer (although it had narrowed the image by a few pixels left to right)
but it suffered from the same problem when viewed on the TV. Since it's a CRT, you expect some
oscillation when things are panning slowly up and down, but the version produced by slowing down to
23.976 and using HCenc with pulldown is far superior. Even the top and bottom picture/black border is rock solid
on the TV.

This file I am working with is an avi of a Disney cartoon, perhaps the animation comes with it's own problems?
At this point, probably the only way to really tell is to acquire the DVD myself, which I may do.

Dave

[hech54]

This file I am working with is an avi of a Disney cartoon, perhaps the animation comes with it's own problems?
At this point, probably the only way to really tell is to acquire the DVD myself, which I may do.

Dave

Just make sure it's NTSC.

[davexnet]

Well I would hope so - since I'm in the USA !

[hech54]

Well I would hope so - since I'm in the USA !

Me too....but how much time did you waste on that PAL video file?

[davexnet]

About 2 days...
but it became a question of curiousness in the end.
I do occasionally acquire PAL media, since I originally came from the UK;
mainly old TV shows.