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  1. Member
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    I converted some VHS videos (camcorder shots) using a stand alone VHS/DVD recorder. Then converted some clips into MP4 format and posted them to YouTube. My relatives and friends are complaining that they look slimmer and their faces distorted. After watching the YouTube videos and comparing it to the .vob clips, I can see they look the same and they are correct. It's distorted.

    I used a Aiseesoft converter and select "original" for aspect ratio because that time, it looked okay to me. Yeah, I noticed the people being a little slender. But I did not want to stretch it sideways a bit thinking the people will complain they are fatter in the video. So my question is, is there a more scientific way of knowing the correctness of the aspect ratio or we can only "eyeball" it? Thanks.
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  2. The "scientific" way is to measure a known object with a shot straight on (e.g. a car tire should be a "perfect circle") . It has to be straight on , not at an angle, or skewed . You might do it in an image editor or video editing software

    If it's squat , oval and too wide ; or narrow and too tall - there is a mistake somewhere in your workflow

    When uploading to youtube, it's better to resize using square pixels (DVD recorders dont' use square pixels) . So a 4:3 format would usually be 640x480, even though the recorded size (in NTSC land would be 720x480)

    My guess would be Aiseesoft is the culprit
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  3. Anything shot on VHS will be 4:3 DAR. That 4:3 image will be in the inner 704x480 pixels of the 720x480 frame when recorded by a DVD recorder. So if you wanted to make a square pixel video you would crop 16 pixels off the width (typically 8 off each side) then resize the remaining 704x480 to 640x480.
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    I should have asked this question before I took the time converting video clips and posting them into YouTube. I experiment on the settings. I took Jagabo's figure of 704x480 as the output frame and chose "FULL" as in fill the frame. No cutting of image as it just stretched to fill the frame. Now, the images look correct. So if I may speak in decimal terms, the correct AR is not 1.3333 but 1.46666, which is the quotient of width divided by the height. Below is the source on the left(4:3) from the DVD and the output preview on the right which is a bit wider. I believe my question has been answered. Thanks.
    Click image for larger version

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  5. Originally Posted by edong View Post
    So if I may speak in decimal terms, the correct AR is not 1.3333 but 1.46666
    .
    .
    I believe my question has been answered.
    I don't, or rather, you didn't understand the answer. The source ratio (720x480) is 1.5:1. After cropping the 16 pixels (to make it 704x480) that ratio is now 1.467:1 as you stated. But that's not the correct square-pixel ratio or resolution. That should be some 1.33:1 ratio (640x480, 512x384, 480x360, etc.).

    Originally, when viewing the 720x480 video unresized, people are too fat. After resizing to 640x480 they become 'normal' looking. So, earlier when you said your family was complaining that they looked too slender (My relatives and friends are complaining that they look slimmer), that's the opposite of the way they should look if you uploaded a 720x480 video to YouTube. So, I have no idea what you uploaded to YouTube. Would you care to point us to a link so we can figure it out for ourselves?

    What I said applies to NTSC videos, but not for PAL videos. Your statements actually make sense if the videos in question are PAL. But you say that's not true.
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  6. There are three aspect ratios to consider:

    1) Pixel aspect ratio, PAR, the shape of individual pixels
    2) Frame aspect ratio, FAR, the frame width and height
    3) Display aspect ratio, DAR, the shape of the final displayed picture

    The relationship between the three is this:

    Code:
    DAR = PAR * FAR
    For example, your 704x480 capture has pixels of 10:11.

    Code:
    DAR = 10/11 * 704/480
    DAR = 10 * 704 / (11 * 480)
    DAR = 7040 / 5280
    DAR = 1.333... = 4:3
    I don't know exactly what Youtube does with aspect ratios when it converts your file, and when it displays it.
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  7. Originally Posted by jagabo View Post
    I don't know exactly what Youtube does with aspect ratios when it converts your file, and when it displays it.
    It does nothing. It treats everything uploaded as if it's square-pixel. There are, however, tags you can add to have it resized to 4:3 or 16:9 at playback:

    http://support.google.com/youtube/bin/answer.py?hl=en&answer=146402
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    First of, I must remind you that I'm a non-techie so bear with me. And apologize I cannot show the faces of those in the videos. Anyway, there is an opening credit that hopefully was a perfect circle when recorded. And remember that the images on the three sources, DVD, converted MP4 and those posted in YouTube, look the same when viewed in my monitor. They "seem" distorted.
    1. Here's the original setting when converted to MP4 when people complained they looked skinny.
    Input 720x480 cropped full image, output setting was 720x480 (zoomed "Letterbox")
    https://vimeo.com/50909590
    Click image for larger version

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    2. Based on Jagabo's explanation/suggestion to cut 16 pixels - input cropped to 704x480, output setting was 640x480 zoomed "Full"
    https://vimeo.com/50909592
    3. Again based on Jagabo's suggestion to cut 16 pixels but this time I want the full image intact.
    Input 720x480 cropped full image, output setting was 656(640+16)x480 zoomed "full".
    https://vimeo.com/50909591

    I believe what I said before that 704x480(zoomed "full") to be my output setting will be a bit wider than the correct DAR.

    Guys, if the above does not make sense to you, bottom line is, I just want to know what output setting will display the correct DAR if I do not want to cut pixels from the sides, given my sources. I'm thinking 656x480 maybe nearest to the correct DAR?
    Thanks.
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  9. 640 * 720 / 704 = ~654.5. But sticking with mod16, 656, is your best bet. That's only a ~0.2 percent error. But your original video probably just has black borders at the left and right edges. Why not just crop them off and use 640x480?

    http://mewiki.project357.com/wiki/Computer_movie_files/Video/Mod16
    Last edited by jagabo; 6th Oct 2012 at 23:28.
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  10. Member
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    Yes, there's a tiny black border on the sides and I might be closest to the perfect DAR if I go for 640x480 ratio. It will involve more mouse clicks, though. But as long as I know now by how much the video should be stretched, I'm happy. Thanks.
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