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  1. Hello, I would like to crop a 4/3 video to 14/9 and then convert it to 16/9. I would like to know how to determine how much to crop from the top and bottom, as well as add black bars on the right and left.
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  2. Resize to 14 by 9, then divide your resulting width by 14. That is going to be your black bar length left and right.

    But you need to use mod2, all sizes and lengths in your calculations should be divisible by 2 for YUV420.
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  3. Assuming source 625/50 and PAR 16:15,

    crop to 14:9 by 720*9/14*16/15 = 498. So, now you have 720x498 PAR 16:15 --> FAR 14:9

    What you need to do next depends whether you want to go to SD or HD and what PAR you want to use.

    Cannot help with a script or ffmpeg params though.
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  4. Member Skiller's Avatar
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    Originally Posted by JAX75 View Post
    how much to crop from the top and bottom
    An easy and universally working approach would be to simply crop to 85.7% of the original height.

    How much to crop top/bottom (each) = ( Height - Height * (4/3) / (14/9) ) / 2


    Originally Posted by JAX75 View Post
    as well as add black bars on the right and left.
    Since most 4:3 videos are standard definition and not using square pixels and we don't know what your target is this cannot be answered yet.
    Last edited by Skiller; 9th Feb 2024 at 19:05. Reason: mistake =D
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  5. Originally Posted by Bwaak View Post
    Assuming source 625/50 and PAR 16:15,

    crop to 14:9 by 720*9/14*16/15 = 498. So, now you have 720x498 PAR 16:15 --> FAR 14:9

    What you need to do next depends whether you want to go to SD or HD and what PAR you want to use.

    Cannot help with a script or ffmpeg params though.
    1.77 via material 720x576 or 720x480
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    In VDub for PAL:

    Resize Filter: with Aspect Ratio "disabled", set New size Absolute: 768x576, OK

    Crop Filter: a total of 82 pixels off top and bottom. This will leave 768 x 494 (1.555 or 14:9).

    Resize again: In 16:9, a 494 height needs a frame width of 878. Check New size Absolute is still 768x494 (with Aspect Ratio Disabled),
    then in Framing Options, tick "Letterbox/crop to size": 878x494, OK ["Letterbox" will actually be pillarboxing]

    Resize again up to a standard 1920x1080 if you wish, as per step 1.

    Done.
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  7. Originally Posted by Alwyn View Post
    In VDub for PAL:

    Resize Filter: with Aspect Ratio "disabled", set New size Absolute: 768x576, OK

    Crop Filter: a total of 82 pixels off top and bottom. This will leave 768 x 494 (1.555 or 14:9).

    Resize again: In 16:9, a 494 height needs a frame width of 878. Check New size Absolute is still 768x494 (with Aspect Ratio Disabled),
    then in Framing Options, tick "Letterbox/crop to size": 878x494, OK ["Letterbox" will actually be pillarboxing]

    Resize again up to a standard 1920x1080 if you wish, as per step 1.

    Done.
    I use Staxrip I suppose it's the same principe in fact I wanted to make it crop like channel tv 14/9 the content 4/3
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  8. Originally Posted by JAX75 View Post
    I wanted to make it crop like channel tv 14/9 the content 4/3
    Was it only the UK who used the 14:9 AR?
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  9. Originally Posted by Bwaak View Post
    Originally Posted by JAX75 View Post
    I wanted to make it crop like channel tv 14/9 the content 4/3
    Was it only the UK who used the 14:9 AR?
    In France also
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  10. Member Skiller's Avatar
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    Using my formula in post #4 let's calculate the cropping for both 576 and 480 lines content.

    For 576:
    How much to crop top/bottom (each) = ( 576 - 576 * (4/3) / (14/9) ) / 2
    How much to crop top/bottom (each) = 41.14 ≈ 42 (nearest mod2)


    For 480:
    How much to crop top/bottom (each) = ( 480 - 480 * (4/3) / (14/9) ) / 2
    How much to crop top/bottom (each) = 34.29 ≈ 34 (nearest mod2)


    Mod2 cropping needs to be respected in case of 4:2:0 color subsampling and is also advised for interlaced videos.
    Last edited by Skiller; 12th Feb 2024 at 16:22.
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