Okay, I don't want to make a tutorial on how to do every frickin little piece of what to encode with what kind of encoder or codec.
I just want to save down a few examples that might be useful to somebody else too. Specially if you are short on encoding and video editing software like me (sony vegas wont open my recorded files any more).
Download ffmpeg as for
linux or
windows.
Since this is a single binary package, you only have to execute the downloaded executable within command line. There's no need to install this - just extract and run

(at least for windows, for linux I'd suggest installing with your package manager that comes with your distribution).
Choose the static package, you will only need
ffmpeg.exe from
bin directory.
Let's start with examples over examples. I will not explain every switch I used in them, maybe if much interest is there. But first have a look at
http://ffmpeg.org/ffmpeg.html - just search for "-ss " or "-ar" and you will find what you are looking for.
Converting my video (H264,Dxtory Core,audio broken) to youtube compatible mpeg4 without sound as its broken anyway.
8Mbit/s seems enough for me, input resolution is about 960x508.
Code:
ffmpeg -i $INPUTFILE -vcodec mpeg4 -an -b:v 8M $OUTPUTFILE
Converting my video to youtube compatible with mp3 sound 128kbit/s.
Code:
ffmpeg -i $INPUTFILE -vcodec mpeg4 -acodec libmp3lame -b:v 8M -b:a 128k $OUTPUTFILE
Cutting out 10 seconds from a video, starting at 16 minutes and 8 seconds, recode it as youtube compatible mpeg4 with mp3 audio 128kbps.
Code:
ffmpeg -i $INPUTFILE -ss 00:16:08 -t 10 -c:v mpeg4 -c:a libmp3lame -b:v 8M -b:a 128k $OUTPUTFILE
When you start in middle of the video, ffmpegs output might look like this:

Mixing two audio sources into one is
currently not possible.
I will add any useful examples when I should know more or looked up a bit more info.
_________________
website – weather station – enjoy and have fun. all the best!