Question

I would like to combine two videos into one. The first video should cover the entire screen. The second video should cover a smaller area at the upper right the screen (thus overlapping the first video).

Ideally the process should be automated. For example with a script that takes two input videos and outputs one movie file.

Can anyone recommend a video editing tool for Linux that would allow me to do this?

PS: The context is lecture recording. The main screen will be covered with a recording of the whiteboard or the presenter's desktop, while the presenter himself would be visible in he upper right rectangle of the screen.

Edit
As a developer I'd be willing to familiarize me with GStreamer and write an application that does just what I need. Would that be a good idea?

Edit 2
Just found this interesting gst-launch script that does almost exactly what I want. Let me try that out.

Answer 1

I asked a similar question in question 71694. I ended up writing a python script to do what I wanted. This was easier than expected and I have ended up with a completely automated solution, though programming skills are obviously required.

Here is my work-flow;

1. Export the input videos to image sequences using ffmpeg
2. Define a configuration file that determines the location of the videos in the output, their frame-rates, start & stop times etc.
3. The python script combines the images using the Python Imaging Library(PIL) and writes them out as a new image sequence
4. use ffmpeg to recombine the output into a video

I am happy to share more details & code if you want to go down this route. Otherwise, I have also used Camtasia (not Linux so probably no use to you) to do produce some basic picture-in-picture stuff (they have nice tutorial here)

Answer 2

This one liner shows you how to do it, just adjust sizes to match your screen resolution.

gst-launch \
    v4l2src device=/dev/video1 \
    	! video/x-raw-yuv,width=352,height=288,framerate=\(fraction\)30/1 \
    	! videoscale \
    	! video/x-raw-yuv,width=640,height=480 \
    	! cairotextoverlay text=1 shaded-background=true deltax=310 deltay=-430 \
    	! videobox left=0  top=0  border-alpha=0 \
    	! videomixer name=mix \
    	! xvimagesink \
    v4l2src device=/dev/video0 \
    	! video/x-raw-yuv,width=640,height=480,framerate=\(fraction\)30/1 \
    	! videoscale \
    	! video/x-raw-yuv,width=1280,height=960 \
    	! cairotextoverlay text=2 shaded-background=true deltax=630 deltay=-910 \
    	! videobox left=0 top=0 border-alpha=0 \
    ! mix.

Answer 3

Fascinating problem. I do not have a out-of-the-box solution but a couple of leads and alternate ways of doing that.

Leads

• See this page they used imagemagick toolkit and some bash scripting (scripts available on the site). They needed to do something more complex than you need, but I suppose the technique is the same.
• There are also various plugins available for FFmpeg. This watermark plugin uses an animated GIF on the main video. Again... different task, but I assume the code is highly recyclable for your ends.

Alternative ways of doing it

• Record them simultaneously! You can use for example cheese to keep a shot of the teacher in the corner of the screen, and recordmydesktop to record the screen as a whole.
• Use a video editor like OpenShot or Cinelerra to do the composite after you recorded separately the two videos.

Hope this helps you a bit in finding your way to solve the problem. Best luck!