Description
A vpVideo object is an R container for an OpenCV video. vpVideo objects can 
be generated by the readVid function in the 
videoplayR library.
Format
A vpVideo object contains three fields:
- "length": the number of frames in the video.
 
- "fps": the framerate of the video.
 
- "dim": the dimensions in pixels (width x height) of the video.
Details
A vpVideo object is not a persistent object, but a pointer to a C++ 
object that cannot be saved for reuse in a different session.