using ffmpeg to scale a video
https://trac.ffmpeg.org/wiki/Scaling
input.MOV is the video that I want to change in size
-vf visual filtergraph, a simple filtergraph
"scale=iw*.5:ih*.5" or you could type "scale=iw/2:ih/2" both will halve the iw (input width) and ih (input height) of the input video
output_half_size.MOV is the video that has been scaled down.
we can scale in other ways for example...
if you want to define the width and height you can type scale=320:240 320 is the width and 240 is the height
if you change the scale it can make the video look stretched or squashed, if you want to change the width and let the command work out what the height should be you can type scale=320:-1 the video is 320 wide and the -1 shows that you want the program to work out the height.
These are the scaling commands that I use the most but if you want to know more then go to the link I have provided earlier and in the notes.
links:
https://trac.ffmpeg.org/wiki/Scaling
00:00 intro
00:23 scale to halve in size
00:56 notes defining size to scale
01:00 notes defining just x or y scale