Video Editing

Playlist file (list of all avi-files which should be merged)

file 'file2.avi'
file 'file1.avi'

ffmpeg -f concat -i plist.txt -codec msrle  -c copy video_output.avi

The -codec option defines the output video codec.
To convert the video in the same step in another format you can give some explicite codec and parameters.
Here the parameters for a Microsoft WMV file with .avi extension

ffmpeg -y -f concat -i plist.txt -an -vcodec msmpeg4 -qscale 0 -b:v 4M -r 5 output.avi

With -qscale the encoder uses the same quantisation method as the input files, for better quality.

Stack movies on top of each other:

ffmpeg -i plist.txt -filter_complex vstack -c:v libx264 output.avi

Next to each other horizontally works the same way, but using the option

-filter_complex hstack