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  1. Member
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    Hello all,

    In all the Video8 tapes played back for capture (amarec, lagarith) there is this banding at the bottom of the frame (capture below). I don't know what it's called so can't research it.

    It looks like there is visual information there which is somehow distorted. Is it possible to "correct" it and get that information, rather than just crop it out?

    During playback in camcorder, LCD viewscreen does not show such banding.

    Cheers.

    Image
    [Attachment 59051 - Click to enlarge]
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  2. Member
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    It is "head switcihng noise".

    http://www.avartifactatlas.com/artifacts/head_switching_noise.html#:~:text=Head%20swit...%20derivatives

    You don't have to crop it, but to mask it. For example with AviSynth

    Code:
    (crop(0,0,0,-X).addborders(0,0,0,X)
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  3. Head switching noise. Different players may have more or less of it. A line time base corrector can clean up a lot of it.
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    Originally Posted by lollo View Post
    It is "head switcihng noise".

    http://www.avartifactatlas.com/artifacts/head_switching_noise.html#:~:text=Head%20swit...%20derivatives

    You don't have to crop it, but to mask it. For example with AviSynth

    Code:
    (crop(0,0,0,-X).addborders(0,0,0,X)
    Thanks for your reply and the link.

    I will look for this feature in Hybrid.
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  5. Google for 'Head Switching Noise'
    When you crop it off and also crop the right black bar off you will preserve the aspect ratio, and you can play it back at the intended DAR without distortion.

    Edit: or as lollo suggested replace it with a black border and keep the 720x480 standard size. Easy with Hybrid.
    Last edited by Sharc; 21st May 2021 at 08:51.
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    Originally Posted by jagabo View Post
    A line time base corrector can clean up a lot of it.
    Thanks for the reply. I'll look up what that actually is. lol
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  7. Member
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    You can also have a look at a procedure that jagabo (who also replied) developed:

    https://forum.videohelp.com/threads/397742-This-is-working-for-me-PAL-VHS-capture-unco...e2#post2587587
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    Originally Posted by lollo View Post
    You don't have to crop it, but to mask it. For example with AviSynth
    Why is masking preferable to cropping?
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    Because you keep the original captured height, that should be "good" (480 or 576), and the "standard" proportions.
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  10. Some codecs and devices require specific frame sizes. For example, NTSC DVD requires a 720x480 or 704x480 frame. Mpeg2 encoding requires mod 16 frame sizes. Cropping is fine if you don't have such restrictions on your intended playback device or codec.
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    Thank you lollo and jagabo for the replies.

    I will use cropping since the purpose is to capture video8 tapes, convert them, and then share with friends via google drive or dropbox, which do not appear to require a standard frame size.

    Cheers.
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  12. Originally Posted by Rahneshin View Post
    I will use cropping since the purpose is to capture video8 tapes, convert them, and then share with friends via google drive or dropbox, which do not appear to require a standard frame size.
    Correct. You only need to assure the frame size is valid for your encoder. You will need at least mod 2 for progressive YV12 video, mod 4 for interlaced YV12, I recommend mod 4 because some old players will not work properly with mod 2.
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    Originally Posted by jagabo View Post
    Correct. You only need to assure the frame size is valid for your encoder. You will need at least mod 2 for progressive YV12 video, mod 4 for interlaced YV12, I recommend mod 4 because some old players will not work properly with mod 2.
    Thanks for your reply.

    By encoder, do you mean the device which converts the analog signal from the camcorder (usb-live2), or the capture software (amarec, vdub)?

    I've seen the term "mod" in Hybrid in Crop/Resize->Base but have not touched it as I am resizing PAR instead to correct a slight 'vertical compression' (people look a little boxy) in my video captures. (This also allows the native resolution of NTSC 720x480 to be preserved while still 'resizing' the image, right?)

    Pretty sure my video captures are interlaced as the artifact(?) is very present in them.

    So, for me, given the above, (and assuming I leave PAR alone) you would recommend, in Hybrid: Crop/Resize->Base, Resize Picture, Resize Method: 10-bicubic spline, Auto adjust: height, to mod: 4. Correct?

    Please forgive all the questions, but each answer you experts give just throws up a whole bunch of new questions! Thanks for your time.
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  14. By "encoder" I meant the codec you use to compress your video. x264, x265, etc.

    If your source is interlaced you should deinterlace (QTGMC is best) before resizing and cropping. Or you can leave it interlaced and encode it interlaced -- interlaced video should be cropped on mod4 boundaries.

    Mod N means integer multiples of N. So mod 4 is 4, 8, 12, 16... 468, 472, 476... 704, 708, 712, 716...
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    Thanks for the info, jagabo.

    These are things I would've never figured out on my own.
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  16. Capturing Memories dellsam34's Avatar
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    I've done some experimenting cropping off all the edges (while respecting the 704:480 ratio) down to the active video area after de-interlacing and resized the resulting resolution to 1440x1080 4:3 using LanczosResize and the quality wasn't that bad, The reason I've done this is because one of the customers requested it and tried to explain to him that it will introduce artifacts but he insisted, I was surprised on how it came out, I posted a sample in a thread but I can't find the post.
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