In the FFmpeg DASH documentation I don't understand the purpose of -window_size which is explained as:
Set the maximum number of segments kept in the manifest.
If my video is 30 seconds long, the GOP size is 4 seconds and the segment length is 4 seconds, what is the meaning and purpose of a parameter to control the maximum number of segments kept in the manifest, when does this parameter need to be used and how do you determine valid values?
I'm guessing that the stream is being loaded into memory and the number of segments in the manifest controls how much is kept in memory at one time but it's just a wild guess and I can't find any further explanation.
I am not live streaming in case it's relevant.
The window size is relevant if you stream live. In a live scenario a player could rewind and the window size determines how far a player could go back. Since you are not live streaming - it is not relevant for you.