[vlc-devel] Meaning of video zoom

[Steve Lhomme]

On 2018-05-24 9:04 PM, Rémi Denis-Courmont wrote:
> 	Hello,
>
> If the SAR and PAR are equal, the meaning of zoom is clear: it is the ratio
> from input samples to output pixels.
>
> But if they are not equal, according to what metric should the zoom be rated?
> I can think of 5 different dimensions to measure it, and they are probably
> others:
> - diagonale,
> - largest,
> - smallest,
> - horizontal or
> - vertical.
> (Not to mention reorientation.)
>
> I guess broadcasting industry reasons in vertical dimension, and display
> industry in diagonales.

The code does this:
*width=*width*cfg->zoom.num/cfg->zoom.den;
    *height=*height*cfg->zoom.num/cfg->zoom.den;

So I suppose that's diagonale.



>
> N.B.: VLC has never measured the PAR to this point. Unless explicitly
> configured (--monitor-par), it is assumed 1:1.
>