[MPlayer-users] Looking for a software to clip a movie camera to size

Gene Heskett gheskett at wdtv.com
Mon Sep 23 14:06:48 CEST 2013

On Monday 23 September 2013 07:30:57 Reimar Döffinger did opine:

> On 22.09.2013, at 20:47, Gene Heskett <gheskett at wdtv.com> wrote:
> > Is there such a video processing module in our 'bag of tricks'?
> That was a bit long, but sure there is vf crop. But if that's all you'd
> want MPlayer for that is overkill.
> Cropping is one pointer add (to reflect the new top-left point) and then
> setting new width and height. At least as long as there is stride
> support it doesn't involve any data processing at all.

Sorry about the length, but I wanted to make it clear what my thinking was.  
I also think the available bandwidth thru a USB port on an intel atom 
motherboard is a speed limitation.  As is the fact that the cnc application 
demands one of the cpu cores, using isolcpus for that, which keeps the 
remaining one busier than a one armed paper hanger doing this too.

But you make this sound like a dead simple thing to do, but my one time 
familiarity with C was 25 years ago when it was straight K&R & CPU's were 
Motorola's & 8 bits wide, so I fear I'm at the mercy of todays coders to do 
this. The software being used now is camunits, which can control the v4L2 
device, but cannot do cropping.  But it uses a rather useless flip module 
that can reverse in either direction, but the ideal camera mounting 
position on the mill would need a 90 degree rotation to make the image 
correlate with what the eye sees, and the flip can't fix that.  That flip 
is at least a frames delay that as a retired television engineer, can't be 
gotten around, only bypassed, which I will try to do.  So in the *nix way 
of doing things with pipes, what would be the name of a video processing 
module that could do this crop in real time?

Doing a search for "video crop", using synaptic to search the repos, 
doesn't come up with anything that doesn't have DVD as part of its 

And the term "stride", is a new one to me.

Thank you, Reimar.

Cheers, Gene
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