I was looking for a way to check avi files for errors and came across this tutorial
. Though its ffmpeg commands work fine but I don't understand what they mean.
$ ffmpeg -v 5 -i episode01.avi -f null -
Now this command works but I don't understand its last option.
I understand that we give the name of the output file in the end but here we have given hyphen(-). How does it affect the ffmpeg? What does it mean? Does it tells ffmpeg there is no output file or does it tells it to dry run on the input file?
$ ffmpeg -v 5 -i episode01.avi -f null - 2> episode01.txt
The above command is used to redirect the output to a file.
Why we have to put a '2' before '>'?
In other commands to redirect the output, I simply have to put a '>'; like 'ls >list', but here redirection doesn't work unless there is a 2 immediately before the '>'.
Why is to so?
Please help me with my confusion. Any explanation will be highly appreciated.