I was assigned to record a screencast for demonstrating look-and-feel of a portal. By the way, my laptop is Ubuntu right now. I don't want to find another machine to do this job so I have to find a way to record my screen effectively. I found How to Create a Screencast in Ubuntu. This is a good article which helps me realize additional capability of ffmpeg. Anyway, the standard ffmpeg does not support this functionality so I have to recompile ffmpeg by myself. Well, I do not like this idea because I will have two versions of ffmpeg in different directory. So I continue finding and finally found how to rebuild ffmpeg in proper way. As a result, I combined 2 approaches as follows.

1. Prepare all necessary packages to build ffmpeg from source

   $ sudo apt-get build-dep ffmpeg

2. Install additional packages to build risky addons of ffmpeg

   sudo apt-get install liblame-dev libfaad2-dev libfaac-dev libxvidcore4-dev fakeroot
   sudo apt-get install build-essential xlibs-dev devscripts

3. Get ffmpeg source

   sudo apt-get source ffmpeg

4. Get x11grab patch

   wget http://un.sh.nu/screencasts/ffmpeg-0.4.9-p20051216.diff

5. Apply the patch (You may get 2 failures in file configure. Don't worry. Edit the file manually will help.)

   cd ffmpeg_0.cvs20050918
   patch -Np1 -i ../ffmpeg-0.4.9-p20051216.diff

6. Modify debian/rules to include below line

   confflags += --enable-x11grab

7. Modify debian/changelog to describe about your modification and version number to prevent autoupdater override this package automatically

   ffmpeg (3:0.cvs20050918-5ubuntu1.x11grab) dapper; urgency=low
   
    * x11grab:
       + Add support for x11grab
   
    -- Sugree Phatanapherom <sugree@gmail.com>  Wed, 21 Jun 2006 21:50:00 +0700
   

8. Rebuild ffmpeg

   $ DEB_BUILD_OPTIONS=risky debuild -us -uc

9. Install the package

   $ cd ..
   $ dpkg -i ffmpeg_0.cvs20050918-5ubuntu1.x11grab_i386.deb

Now I have a customized version of ffmpeg which supports x11grab extension for real-time recording screen and another audio source with the same build options of that in original ffmpeg compiled. In order to record a screencast, I just run below command.

$ ffmpeg -vcodec mpeg4 -b 1000 -r 10 -g 300 -vd x11:0,0 -s 1280x768 -an test.avi

where:

• -vd x11:0,0 specify x11 as video device at offset x=0 and y=0
• -b 1000 specify video bitrate
• -r 10 specify video frame rate
• -s 1280x768 specify video size
• -an specify to exclude audio

If you want to record audio, just ignore -an and run ffmpeg under esddsp to make it run concurrently with other application properly. To resize the video, run below command.

$ ffmpeg -vcodec mpeg4 -b 1000 -r 10 -g 300 -i test.avi -s 800x600 test-800-600.avi

Now it's time to play.

$ mplayer -vo x11 test.avi

Happy screencast!

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