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

Gene Heskett gheskett at wdtv.com
Sun Sep 22 20:47:59 CEST 2013

Greetings all;

The movie camera is one on Logitechs top models, with a resolution 
somewhere above 2kx2k, auto focus etc.

Its being used with a utility that can be integrated into the LinuxCNC axis 
GUI, with facilities being utilized for machine vision.

However, by the time it actually gets to the window in the gui, all the 
processing that huge image undergoes takes so much time that the windows 
refresh rate is about 1 frame a second, and the actual video image we see 
is 4 or 5 frames old, so you stop the machine and wait quite a few seconds 
for the output video to get through the system and display.

This obviously isn't conducive to learning how to use it productively 
since, in the case of milling a printed circuit board, I can drill a hole 
through the board in a known location, turn the board over, drive the 
machine to put that drill into the hole and execute a command that tells 
the machine I don't care where you think you are, you are in fact here, 
giving it the known coordinates of the hole.

It occurs to me that since  most of this utilities image processing is 
modeled on a 640x480 image format, the decimation of all that data into a 
640x480 format has to be a huge time killer, whereas if we handed it a 
640x480 format signal in the first place, 80% of all that data shuffling 
could just go away, giving a speedup that would make it usable.

Since the nature of this sort of job would have more accuracy if the camera 
had a zoom lens, which it does not, the fix would seem to me to be in 
determining the center  of the image, calculating 240 lines up and 240 
lines down and using that as a gate, then calculating 320 pixels to the 
left & right & using that for a gate too, so that the output then would be 
the 640x480 we need, throwing away the rest of the data in real time.

The rest of the processing chain could then spend its time generating the 
crosshairs and bullseye target circles supered on that, and do it at 5 to 
20 frames a second.  That would be approaching real time enough to make it 

Is there such a video processing module in our 'bag of tricks'?

Cheers, Gene
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
My web page: <http://gene.homelinux.net:6309/gene> should be up!

One thought driven home is better than three left on base.
A pen in the hand of this president is far more
dangerous than 200 million guns in the hands of
         law-abiding citizens.

More information about the MPlayer-users mailing list