[FFmpeg-user] prevent clean aperture value cropping

[edit 'B]

> On 15 May 2025, at 13:56, BloodMan <bloodman at gmail.com> wrote:
> 
> Hello,
> 
> Everything indicates that:
> 
> 1. The real, stored, image resolution is 702x576   (702/3/4? weird)
> 
> 2. The display resolution is set to 720x576
> 
> 3. Additionally, there is information about the image positioning offset 702x576 in 720x576 resolution (in MOV headers)
> 
> So:
> 
> There is no possibility of obtaining a 720x576 result image because there is no such thing in the file - and the only possibility is to use the rescale OR overlay filter to place 702x576 at 720x576 black;
> and reencode.
> 
> 
> greets,


If this is the case, it’s an FFmpeg bug to ‘bake in’ what should only be metadata.
I can add CLAP altering support to QTchange if needed. A simple operation then would change or remove aperture info.

Bouke



> 
> 
> W dniu 2025-05-15 o 13:24, Christian Sievers via ffmpeg-user pisze:
>> Hello,
>> It looks a lot like the file is actually cropped. At least, I can’t find a player or tool that tells me that the 720 px are still there. See the bottom for mediainfo and exiftool reports for the FFV1 file.
>> Yes, the strange thing is, I did run frameMD5 checks on original and resulting copy, and ffmpeg tells me they’re identical. Does that mean that ffmpeg calculates the MD5s from the clean aperture value frames; ignoring the video content outside?
>> I may be wrong (hey, sounds more likely than the option that I just noticed something strange that nobody else has), but to me it does look like ffmpeg is deleting info without telling me.
>> Here’s another sample file, with the original v210 video track. It's 4 seconds long and 55 MB in size. https://videolooper.de/1913_trim.mov
>> At this point, this is about to turn into an academic question, because we might just keep our v210 files for now. But I’m happy to assist where I can, if anyone thinks this is something that needs to be fixed in ffmpeg.
>> Best,
>> Christian
> 
> 
> -- 
> Pozdrawiam,
> bloodman at gmail.com
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