I need to convert a bunch of video files using FFmpeg. I run a Bash file that converts all the files nicely, however there is a problem if a file converted is not in 16:9 format.
As I am fixing the size of the screen to -s 720x400, if the aspect ratio of the original is 4:3, FFmpeg creates a 16:9 output file, screwing up the aspect ratio.
Is there a setting that allows setting an aspect ratio as the main parameter, with size being adjusted (for example, by fixing an X or Y dimension only)?
I've asked this a long time ago, but I've actually got a solution which was not known to me at the time -- in order to keep the aspect ratio, you should use the video filter scale, which is a very powerful filter.
You can simply use it like this:
-vf "scale=640:-1"
Which will fix the width and supply the height required to keep the aspect ratio. But you can also use many other options and even mathematical functions, check the documentation here - http://ffmpeg.org/ffmpeg.html#scale