How to speed up a script writing frames using a 'VideoWriter' object?

I am writing a script involving capturing frames of a figure window using the 'getframe' function, and writing each frame using a 'VideoWriter' object to a file.

However, this is quite a slow process if I have many frames to acquire and write. How can I speed it up?

Answer 1

[MathWorks Support Team]

If many calls to 'getframe' are occurring in succession, it is more efficient to avoid calling the 'writeVideo' function every time a new frame is to be written.

Instead, try using the 'repmat' function to pre-initialize a data structure containing a series of video frame structs returned by 'getframe', and write them all to the file at once using 'writeVideo', like so:

 

>> frameArray = repmat(getframe(figure), 100, 1)

frameArray = 

  100×1 struct array with fields:

    cdata
    colormap

This will minimize the amount of calls to the 'writeVideo' function, as well pre-allocate as much space as is needed to store the frames.