This simple guide is for windows users but should work as easily under linux or mac.
Put all your files and daily folders in /record/ into a folder, example /wizemerge/
Press start key and type “cmd” to open command line.
Go to that folder by typing “cd folder” until you’re into it.
for me that was;
dir /s/b *.mp4 > list.txt
This will print a list of all mp4 files in all subdirectory into a file called list.txt
Open that file and make it compatible with FFMPEG by turning
Open a text editor and use replace tool, CTRL-H
Now download a copy of FFMPED and put it into that same folder.
then type the command
ffmpeg.exe -safe 0 -f concat -i list.txt -c copy all.mkv
to create a single video called all.mkv
It should be very fast as there are no re-encoding.