Only half my scanlines working? - AVS Forum
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post #1 of 3 Old 04-05-2002, 08:49 AM - Thread Starter
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I really shouldn't post messages when i don't have all my facts but i can't stop thinking about this. I'm at work and the equipment is at home so i can't verify/test anything until tonight.

JVC 32" D501 non-anamorphic, non-progressive tv. It's the higher end JVC non-hd tvs.
Pioneer DVD440 non-progressive player
Anamorphic DVDs. 1.85:1 and 2.?ish:1 DVDs. AI is an example.
Using 3 component video cables(never even hooked up s-video or composite)

Ever since i bought the DVD player i've noticed subtitles and credits being rather difficult to read on DVDs. At one point i was right up by the TV and i noticed how it seemed like everything was being displayed with only half the scan lines. In other words it was constant lines of black, picture, black, picture, etc all the way down the screen. I thought a non-interlaced picture meant that each field would alternate between which lines were black and which lines were picture. Field #1 has lines 1, 3, 5, 7, etc as picture and field #2 has lines 2, 4, 6, 8, etc as picture. On my TV it looks like it's always ONLY showing picture on lines 1, 3, 5, 7. I didn't think about wether that was correct or not. My mind registered something about scanlines and then convinced itself to stop thinking. Sitting back on the couch you don't really notice it that much in the regular picture, you just notice subtitles being hard to read.

Yesterday while wandering through the deparment store i looked at some of the display 27" TVs showing regular cable. As i looked i noticed something. No obvious black spaces. The pictures were pretty muddy (cheap cheap cheap tvs) but there were no constant black gaps. This is what i expected. The interlaced picture alternates fast enough so that for the most part it feels like a complete picture.

Am i on crack?

Tonite i'm going to test what regular cable looks like and compare it to DVDs. I really dont' know if the black spaces are visible on regular cable on my tv or only during DVD playback.

Some thoughts i have are:
- Maybe this only happens when playing DVDs. Is it my player? is it an artifact of the player converting an anamorphic DVD to non anamorphic? I'll try a non-anamorphic DVD.
- Maybe i'll see a difference if i use s-video or composite. (component jacks defective?)
- Maybe the size difference from a 32" to a 27" is enough to really exagerate these black spaces. But this just seemed more severe than the size difference.
- Tv settings are all at mid level. sharpness, bright, contrast, etc. Nothing is overly high.
- Maybe my tv is defective.
- Maybe i was seeing things.

Anyone have any thoughts? I understand what a 480i pictures is. I know what an anamorphic dvd is (my TV does not have the squeeze). I understand that the bigger the tv, the more space there is between scan lines. But somehow i'm confused.

Sorry for rambling. Just trying to squeeze out all the quality i can from this system until i can afford and choose a HDTV.
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post #2 of 3 Old 04-06-2002, 05:22 PM
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Hi,

If subtitles are hard to read on DVD's, then there is a possible defect somewhere. (For example, subtitles with some font outlines missing and some font outlines seemingly 2 pixels tall. Or subtitles that look excessively pixellated as if they were 6-point font)

I have seen some TV's that are defective and overlap the field rather than properly interlace them. (Scalines 2, 4, 6, 8 etc. are overlapped on top of 1, 3, 5, 7, etc.)

I have seen defective DVD players that do not output a proper interlaced signal, so it may not be the TV's fault. You may want to test out a different DVD player.

Thanks,
Mark Rejhon

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BlurBusters Blog -- Eliminating Motion Blur by 90%+ on LCD for games and computers

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post #3 of 3 Old 04-08-2002, 01:54 PM
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Quote:
Originally posted by Mark Rejhon
I have seen defective DVD players that do not output a proper interlaced signal, so it may not be the TV's fault. You may want to test out a different DVD player.
I was thinking along the same lines. Does the problem only happen when playing anamorphic DVDs, or does it happen with full screen (and non-anamorphic letterbox) ones too. If it only happens with anamophic titles, the anamorphic downconversion in the DVD player is to blame. I'm not familiar with the DVD440, but some players don't do anamorphic downconversion very well.
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