If you've just installed VBox and it is not starting or working, the most common problem is usually that you don't have your kernel source installed, which means there is no kernel driver for vbox so it can't work.
You may get an error that says "Kernel driver not installed" in your Virtualbox.
So the first thing you should do is install your kernel source by running this:
sudo apt-get install linux-headers-`uname -r`........
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 -........
yum -y install --skip-broken package-you-want-to-install
Packages skipped because of dependency problems:
php56w-mysql-5.6.30-1.w6.x86_64 from webtatic
Error: Multilib version problems found. This often means that the root
cause is something else and multilib version checking is just
pointing out that there is........
I dread updating the kernel and rebooting to find the Ubuntu graphics aren't working and you have to manually intervene. This is usually because Ubuntu for whatever reason didn't update the drivers you need (eg. the manually compiled Nvidia Kernel driver that MUST be recompiled for each and every kernel update unfortunately).
The most common reason may be that "linux-source" hasn't been installed automatically on my system. I tried to manually reinstall the........
Have you ever found a website/page that has several or perhaps dozens, hundreds or thousands of files that you need downloaded but don't have the time to manually do it?
wget's recursive function called with -r does that, but also with some quirks to be warned about.
If you're doing it from a standard web based directory structure, you will notice there is still a link to .. and wget will follow that.
Eg. let's say you have files in http://serverip/documen........