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  1. Member
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    This video I attached was recorded with a Panasonic X900 Camcorder in Full HD. When it is downconverted to PAL DVD resolution, the electric cables in the video become zig-zag. What causes it? Is it possible to have straight, even lines without zig-zags when converting to DVD, or this is something you cannot avoid? I attached a screenshot about this problem in the DVD video, too.
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  2. Originally Posted by Bencuri View Post
    This video I attached was recorded with a Panasonic X900 Camcorder in Full HD. When it is downconverted to PAL DVD resolution, the electric cables in the video become zig-zag. What causes it? Is it possible to have straight, even lines without zig-zags when converting to DVD, or this is something you cannot avoid? I attached a screenshot about this problem in the DVD video, too.


    Because it's interlaced. Interlaced PAL DVD is 50 fields per second (50i or 25i, both are the same thing, just different naming conventions), Not 50 frames per second . You can think of each field like half a frame, contains only 1/2 the spatial information. When you pause it like that you 're looking at a field resized to full size frame, so you will see aliasing artifacts or "jaggies". When viewed in motion, those "jaggies" can buzz or flicker, also known as "bob flicker"

    Only way to avoid these artifacts is to keep progressive (full frames), but 50p is not supported by DVD . Only 25p. So you will lose the motion smoothness

    "good" software bob deinterlacing (convert 50 fields to 50 frames) methods fill in those jaggies by interpolation and looking at fields before/after. They look almost perfectly smooth. Most HDTV's use simple bob deinterlace (simple resizing) , and the quality is poor compared to complex software methods like QTGMC in avisynth . Some more expensive HDTV's have motion adaptive deinterlacing algorithms, but even the best ones are worse than QTGMC . Essentially what I'm saying is when you have interlaced DVD, you're at the mercy of the HDTV's quality of deinterlacing. Some are pretty good, some are very bad.

    You can see the difference good deinterlacing quality makes; most flat screen TV's will use a simple bob only, because the other algorithms require more CPU and processing power, not suitable for realtime playback , or it would cost too much to the price of a TV to add such a feature

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    Last edited by poisondeathray; 19th Apr 2013 at 17:11.
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    So when converting from Full HD 50p, there is no hope solving this problem, when the target is DVD 50i?

    What if I record in Full HD 50i? Can that solve the problem?

    Anyway, loosing motion smoothness with 25p DVD may not be a problem if the TV can be adjusted to play it back in 50i, or 50p with interpolation, like that method that Samsung TV's use, that Smart Motion, I guess they call it like that. What do you think?

    If you connect the DVD player with an analoge TV, how will that display the 25p DVD, if 25p signal leaves the DVD? Will it be 50i? In that case a 25p DVD might be okay. Or zigzags will appear then, too, when the TV starts convering the 25p to 50i, too?

    I am not sure however how avisynth relates to this case? I guesst that kind of software deinterlacing is only useful when you want to convert an interlaced video to progressive, isn't it?

    What playback software do you recommend anyway that can handle these zigzags well?
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  4. Originally Posted by Bencuri View Post
    So when converting from Full HD 50p, there is no hope solving this problem, when the target is DVD 50i?
    No hope to solve the underlying issue.

    The only way to "improve" it is to use a better deinterlacer during playback (either software, or more expensive TV set)



    What if I record in Full HD 50i? Can that solve the problem?
    No. The same analogous problems occur at 1080i50 on a blu-ray player (because 1080p50 isn't supported by blu-ray, only AVCHD2.0 at 28Mb/s). In fact, the method used for interlaced resizing can make the problem far worse. (1080i50 => 720x576i50)


    Anyway, loosing motion smoothness with 25p DVD may not be a problem if the TV can be adjusted to play it back in 50i, or 50p with interpolation, like that method that Samsung TV's use, that Smart Motion, I guess they call it like that. What do you think?
    It depends on the content and shooting. If you've done a good job, and there is little motion to begin with you can make a 25p DVD fine . It would be poor choice for something like shooting sports, for example

    It also depends on the TV set. The interpolation methods often lead to worse artifacts than the jaggies (funny morphing edges)

    Try it out and find out


    If you connect the DVD player with an analoge TV, how will that display the 25p DVD, if 25p signal leaves the DVD? Will it be 50i? In that case a 25p DVD might be okay. Or zigzags will appear then, too, when the TV starts convering the 25p to 50i, too?
    No, 25p DVD is fine . That's the benefit of progressive . (The output signal is actually "25p in 50i" or 2-2 pulldown , but it will look like full progressive frames on a PAL dvd player + any TV setup.)


    I am not sure however how avisynth relates to this case? I guesst that kind of software deinterlacing is only useful when you want to convert an interlaced video to progressive, isn't it?
    It was meant to illustrate a different method of deinterlacing. If your computer is fast enough, you can play a video with an .avs script . For SD resolutions, a typical computer these days will have no problems . (HD is another story)


    What playback software do you recommend anyway that can handle these zigzags well?
    Most playback software won't have advanced deinterlacing algorithms built in .

    With nice progressive 1080p50 content, I would recommend not making a DVD . Seriously.
    Last edited by poisondeathray; 19th Apr 2013 at 18:01.
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    Thank you for your help!
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  6. I use 30p DVD's and no problem (but from 30p source), so 25p will not be a problem also. You will see everything fine on CRT also. The only problem is how to make real 25p DVD yourself, because DVD authoring softwares tend to have their presets to 50i, so you have to be carefull checking settings while encoding. You have to make correct video streams, video 25p and audio AC3 and use some DVD authoring that will make DVD out of those streams.

    Load avisynth script into HCencoder, where you drop every other frame, it is a safe way to make 25p from 50p. Shutter speed for video should not be short, but decent , so there is no obvious gaps in the video. The cheaper camcorder the shorter shutter speed I guess, so with that Panasonic it should not be that bad, or manually set shutter speed to 1/50 (perhaps you will use ND filter outside) or 1/100.

    Editing softwares may blend frames from 50p to 25p while exporting , you experiment.
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    Thanks.

    I had a 25p mpeg, it was zigzag, too, I have just noticed in Mediainfo that it is in fact 25i.

    So I really need to experiment.
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