[FFmpeg-user] filters zoompan and crop

[Jim DeLaHunt]

On 2018-10-28 23:15, Gyan wrote:

> On Mon, Oct 29, 2018 at 11:38 AM Jim DeLaHunt <list+ffmpeg-user at jdlh.com>
> wrote:
>
>>    A zoom
>> argument of /k/ is interpreted as if the input image was drawn /k /times
>> its original size, or equivalently, that the output image is 1//k/ the
>> size of the input image.
>>
> That should be k^2. A zoom value of 2 crops a window of one-half width and
> height, so one-fourth area.
Agreed. By "size" I meant linear dimension, not area or pixel count.

So I think Gyan and I are both saying, interpret the "zoom" argument in 
terms of linear dimension, which means the resulting pixel count or area 
changes in terms of 1 divided by the square of the "zoom" argument.

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