DVD Playback: Pulsating video / vibrating horizontal lines

[mltwitz]

I noticed, that when I get close to my TV screen and watch a DVD play, the picture is somewhat "pulsating", it switches randomly between sharp and blurry, it's especially evident in stills or cartoons with not too much motion. Also, horiztonal lines seem to vibrate, it's ugly! I have a Sony HD Widescren TV (set to P-scan), my Philips DVD player is brand new, also P-scan. I bet this is a know phenomenon, can someone fill me in, is there any way to adjust this?

[guns1inger]

I would venture two separate problems.

One sounds like the effect you get from using a transcoder to reduce the size of a DVD - e.g. DVD Shrink. The sharp frames are the I-frames, which essentially contain a full image, while the subsequent frames contain only the changes. The transcoder removes data from all frames to reduce overall size, but the effect is a clear I-frame, then a progressively softening picture until the next I frame. It is also known as pumping. You should not see this on good quality encodings.

The second sounds like interlace shimmer. Where thin horizontal lines are switched on and off rapidly as the fields are drawn. You should not be seeing this on a progressive scan TV unless the player or the TV are not converting the image to progressive very well.

There may be other explanations, but your description sounds like these to me.

[Guiboche]

Most likey the second. Since there are 2 ways your TV could process the incoming signal.

One: It detects incoming film content. Removes the pulldown, and introduce it's own new progressive 3:2 pulldown turning it into 60p, via frame duplication.

Two: It doesn't detect film content, therefore, treats all incoming signals as interlace. This will create that interlace shimmer, or horizontal lines you're talking about.

The only way to fix this is to have a progressive can DVD player.

But, for all intensive purposes, as bad as it looks, it's not a technical problem, but limitation created by a DVD player, TV, or sometimes both.