When things go wrong your video is basically unplayable or the first video plays fine and then freezes when moving on to the next. Generally if both videos weren't produced with the exact 100% same settings you will have issues. You can try the basic concat but it often won't work right.
Solution for me:
My example uses 3 videos in total so "n=3" and a=1 to include audio.
ffmpeg -threads 12 -i file1.mp4 -........
package kernel-xen-2.6.18-274.7.1.el5.x86_64 is intended for a x86_64 architecture
Linux etc 2.6.18-274.7.1.el5xen #1 SMP Thu Oct 20 17:06:34 EDT 2011 x86_64 x86_64 x86_64 GNU/Linux
As you can see above architecture and kernel is 64-bit but I had to force it to install using "--ignorearch"
Solution
#rpm --ignorearch -ivh kernel-xen-2.6.18-274.7.1.el5.x86_64.rpm
Preparing...&nb........
gocr works great and it's simple, just invoke it like so:
gocr filename.png
The output will be printed to the screen.
My only complaint/concern is that even with standard terminal output (not scanned) from a printscreen, gocr does make mistakes by inserting extra spaces where they don't belong, mistaking letters for numbers etc.. but it's definitely enough to be readable and figure out what you're looking at.
I haven't tested yet with scanned input........