How to merge two files with ffmpeg without

Question

I would like to merge two files with ffmpeg, but instead to simple add one video to the end of the other, I want that both videos play at same time with one video using all the screen, and the other a small square at the right-bottom at the screen(it`s something like the hangout screen).

Is this possible?

Thanks,

Answer 1

So after google it for a while I find out a way:

ffmpeg -i input1 -i input2 -filter_complex \
"[0:v]setpts=PTS-STARTPTS, pad=iw*2:ih[bg]; \
[1:v]setpts=PTS-STARTPTS[fg]; [bg][fg]overlay=w; \
amerge,pan=stereo:c0<c0+c2:c1<c1+c3" output

Based on http://ffmpeg.org/pipermail/ffmpeg-user/2013-June/015662.html