I am using a Matlab code to record a video file using the VideoWriter function. I want to change the code to record only a certain part of the video file rather than the whole video. What command can I use to record only the first 40 secs of the data recorded at normal speed? I also want to know if there is a way I can record only a small part from the middle of the data recorded.
You can add conditional statements such as if to control the writing of the video file.
Alternatively, you can wrap the video writer function into a wrapper, which accepts your actual data, and a control boolean.
If you mean you want to record 40 seconds for each data set, with different frame rates, a wrapper function that takes frame rate and time length, and calculates the frame counts for itself may work.
If you mean you are frequently changing data sets, which will add up to one piece of video, and you want it be 40 second long, then a 'global' variable storing how many seconds you have recorded, as well as a function to calculate time increments, is needed.
Edited -
Based on your refined details, you may find these necessary and - hopefully - helpful.
a wrapper function that does the following job (and takes arguments accordingly):
You can make it fancier by making it able to cut a piece of data series somewhere in the middle, so for example a 10-second data won't add the extra 4 seconds, if you already have 34 seconds on file.