Parameters
Frames : Set frame rate (frames per second). Max value 10, default 5.
Start : Seek to given time position in seconds. "hh:mm:ss" syntax is also
supported. Default is from start
* 100 - begin from second 100
* 01:40 - begin from minute 1 and second 40
Duration : Restrict the captured video sequence to the duration specified in
seconds. "hh:mm:ss" syntax is also supported. Default is all duration
* 200 - take 200 seconds from start
* 03:20 - take 3 minutes and 20 seconds from start
Scale : Set width:height , if one parameter is -1 it will automatically determine the
other while preserving the aspect ratio. Default is 320:160: MAX 480
* 400:400 set width = 400 and height = 400
* 380:-1 set width = 380 and height automatically preserving the aspect ratio
* -1:320 set height = 320 and width automatically preserving the aspect ratio