HowTo Create A Screencast

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Revision as of 12:28, 25 April 2011 by Paul Blankenbaker (talk | contribs) (Capturing)
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This page provides some notes on creating Screencasts using a NST system.

Installing Packages

We have found that the gtk-recordmydesktop provides a simple and free method for capturing screens and producing a screen cast. The totem package provides a viewer for the Ogg Video format screencasts (the VLC media player is also capable of playing back these files). To install these packages:

yum install gtk-recordmydesktop totem

Sound Card Configuration

Configuring and choosing the sound card for gtk-recordMyDesktop can be difficult on systems with multiple sound devices. Here are some tips:

ALSA sound sources are used by gtk-recordMyDesktop and by default, the ALSA sound source of hw:0,0 is used if you leave the sound device set to DEFAULT. To see what sound devices you have available, use the following command:

[pkb@rice ~]$ cat /proc/asound/cards
 0 [SB             ]: HDA-Intel - HDA ATI SB
                      HDA ATI SB at 0xfe024000 irq 16
 1 [HDMI           ]: HDA-Intel - HDA ATI HDMI
                      HDA ATI HDMI at 0xfdffc000 irq 19
 2 [Headset        ]: USB-Audio - Logitech USB Headset
                      Logitech Logitech USB Headset at usb-0000:00:12.0-2, full speed
[pkb@rice ~]$ 

From the output above, there are 3 ALSA sound sources available. To use the Headset, I needed to change the sound device in gtk-recordMyDesktop from DEFAULT to hw:2,0.

To adjust the recording levels, I used alsamixer.


To create your screencast:

  • Launch the gtk-recordMyDesktop application. From the GNOME Desktop, it should be found under the Applications | Sound & Video menu.
  • There are numerous Advanced Options that can be adjusted before starting your capture. If you are only intending on capturing a single window, you may want to consider turning off the Include Window Decorations option (especially if your window contains a Virtual Machine, VNC, or RDP session).
  • After adjusting your options and selecting a window (if not recording the entire desktop), you can press the Record button to start the recording.
  • The small red record button on the GNOME panel will turn into a small gray square stop button. At this point you can start talking and using the application.
  • When you are done press the small square button on the GNOME panel.
  • At this point the raw screen capture data will be encoded and the output file will be saved. By default this will be save to the file $HOME/out.ogv unless you press the Save As button before recording.

It's highly recommended to make a short test screencast to verify your settings (it's easy to have the wrong sound device selected).