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  1. mr. Eric-jan's Avatar
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    Originally Posted by lollo View Post
    The wrong (3:2) aspect ratio was already "baked" into the Elgato capture, so no points for anybody this time
    There is no flag for DAR in a lossless captured avi file. You're probably talking about the SAR (Storage Aspect Ratio = 720/480) which is not present as well, but is just "created" reading the width and height.

    If you write about captures, you should have known this.

    Mediainfo is a reasonable "inspection" program
    Mediainfo just reports what is written in the tags/fields, which can be true or false. It does not analyze the video in any way.
    Okay, thankyou, i never had these problems before, because i capture/record with ProRes422LT.
    Is there any good "inspection" program to read out video file properties, for MAC i prefer, or Windows, i notice also i can't load a .avi file into Davinci Resolve..
    I guess i'll stick to ProRes422LT seeing all this.
    When i convert (625i50) analog to SDI my Video Assist monitor/recorder still states the resolution as 625i50 at the SDI input
    Sorry OP, for being off subject, working with avi files is out of my league

    btw.. my guess is that this is also a VHS copy-recording from another tape format, the orginal recording was made on a camcorder,
    The original camcorder tapes are not available anymore ?
    Last edited by Eric-jan; 28th Aug 2023 at 20:14.
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  2. Captures & Restoration lollo's Avatar
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    Is there any good "inspection" program to read out video file properties, for MAC i prefer, or Windows,
    If that was a question, the answer is: your eyes. There is nothing better than your own judgement to understand the "architecture" of a video. Open it and check field by field, frame by frame, telecine/interlacing structure, analyze levels, colors, parameters (DAR, SAR, PAR), etc.

    i notice also i can't load a .avi file into Davinci Resolve
    master poisondeathray wrote some posts in the recent weeks about that, search the forum.

    When i convert (625i50) analog to SDI my Video Assist monitor/recorder still states the resolution as 625i50 at the SDI input
    I do not understand what you want to say, sorry
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  3. Member Skiller's Avatar
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    Well in my opinion, if you want to do it right, you don't use DAR at all, ever. Crop then apply SAR(*) of analog NTSC video which is 10:11. This btw. also means the DAR of an uncropped 720x480 video is not 4:3, it is 15:11.


    (*) Edit: Sample Aspect Ratio, same as PAR
    Last edited by Skiller; 29th Aug 2023 at 12:56.
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  4. Captures & Restoration lollo's Avatar
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    Yes, he can also crop and specify PAR (your SAR definition is different than mine, I used SAR as Storage Aspect Ratio). But I doubt Eric can manage that, even because he uses a GUI.
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  5. Member Skiller's Avatar
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    Originally Posted by lollo View Post
    your SAR definition is different than mine, I used SAR as Storage Aspect Ratio
    Ah yes, there may be confusion because both are abbreviated the same.

    What I mean by SAR is "Sample Aspect Ratio", which is essentially the same as PAR "Pixel Aspect Ratio".
    Sample Aspect Ratio is technically the right term for analog video, but maybe PAR is the more sane term to use.
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    Originally Posted by Skiller
    This btw. also means the DAR of an uncropped 720x480 video is not 4:3, it is 15:11.
    @Skiller, for square pixels, what is the correct NSTC frame? 720x528?
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  7. Originally Posted by Alwyn View Post
    Originally Posted by Skiller
    This btw. also means the DAR of an uncropped 720x480 video is not 4:3, it is 15:11.
    @Skiller, for square pixels, what is the correct NSTC frame? 720x528?
    Any 15:11 ratio. 720x528 is one. ~654x480 is another. The math is trivial:

    if you want a specific height:
    Code:
    new width = desired height * 15 / 11
    or if you want a specific width:

    Code:
    new height = desired width / 11 * 15
    So if you want a 480 pixel high frame:

    Code:
    new width = desired height * 15 / 11
    new width = 480 * 15 / 11
    new width = 654.545454...
    You can't have a fractional or odd width (with 4:2:0 or 4:2:2 subsampling) so truncate to 654.
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  8. ... or if you crop the 720x480 NTSC capture to 704x480, the resized (square pixels) frame will become the "familiar" 640x480, or 720x540, or 1440x1080; all exactly 4:3.

    Added:
    For random cropping you have to do the maths, or simply crop as you like and encode with SAR 10:11 (x264, mp4 container) and let the TV do the rest. Just don't force the TV to play it as 4:3.
    Last edited by Sharc; 30th Aug 2023 at 02:27. Reason: Added
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