[MPlayer-users] Cropping in original-size vs reduced-size

[Jorge Fábregas]

On Saturday 24 March 2007 2:22 pm, Nico Sabbi wrote:
> cropping weighs next to nothing on the cpu, thus performance will not
> be sensibly better with method #2

I have no performance problems at all and actually, performance is not an 
issue for me with this. My main concern is the correctness of the vertical 
compensation applied during the scaling (assuming you have to remove some 
noise from top and bottom). 

> on the other side the contrast  between black bands and actual video leads
>  to an inefficient utilization of the bitrate at disposal of the encode, so
> #1 is  preferrable.

No...In both cases I'm cropping before the actual encoding. It's just that in 
one example I downscale before cropping and in the other one I crop before 
downscaling.  Those were video filters and I understand these 2 (crop & 
scaling) are applied BEFORE the actual encoding. 

> As I wrote in my previous mail in both cases you will distort your
> encode if you don't use scale=x':-10

Could you please explain the '-10" part?  I read the man page but I still 
don't get it quite well.

Thanks Nico.

Regards,
Jorge