Live Screencasting

Screencasting captures the activity on your desktop and sends it to the other participants in the room. The participants see a real-time view of an application window or selected region of your desktop, and hear your voice if you happen to be speaking. Recorded archives will also include any screencast activity.

Screencasting is a broadcast solution, not a remote control solution. For security reasons, participants in the room have a read-only view of your desktop.

To begin a screencast, click the Live Screencasting button on the whiteboard toolbar. The screencast button is available only to participants who have Upload privileges on the whiteboard:

To the right of the Live Screencasting button is a down-arrow that selects the Screencast Mode:

Screencasting operates in one of two modes:

  1. Area of Screen : Choose a rectangular region of your desktop to share. This region need not correspond to the boundaries of any particular window. Whatever is visible on the desktop in the selected area is what will be sent out to the room.
  2. Window Selection : Choose a particular window from your desktop. The term “window” does not necessarily mean a top level application window — most applications have a series of smaller windows that make up the overall application. The selected window determines the Area of the Screen. Therefore, like the Area of Screen option, whatever is visible on the desktop in the selected area is what will be sent out to the room. That is, the selected window itself will be captured only if it happens to be topmost. This option is available on Windows only.

Area Selection

When starting a screencast in Area Selection mode, the web conference room is hidden, and a “light box” appears over the selected area.

The entire light box can be dragged to a different area of the screen, or it can be resized by dragging any of its edges.

Once your area selection is final, press the Enter key to begin the screencast, or press the Esc key to cancel.

Window Selection

When starting a screencast in Window Selection mode, the web conference room is hidden, and a Window Selection tool is shown.

Drag the selector over the window that you wish to screencast, then release the mouse button to start screencasting. Or, press the Esc key to cancel.

Screencast In Progress

Once a window or area selection is made, the web conference room re-appears. The area containing the browser/whiteboard is now hidden, and the presenter’s name appears with a screencasting icon beside it:

During the screencast, the presenter continues to work normally in the selected application or area of the screen. All other participants in the room see a real-time picture of the selected area of the presenter’s desktop.

As a reminder to the presenter that a screencast is ongoing, the application icon in the system tray alternates between the screencast icon and the icon for the conference room:


The presenter can end the screencast at any time by de-selecting the Screencasting button:

In addition, any moderator in the room can end the screencast by selecting Terminate Screencast from the Moderator menu:

Screencast Complete

Once the screencast has ended, the last view of the screencast region is uploaded to the whiteboard. At this point, the screencast picture can be annotated like any other whiteboard content.

If a slide presentation was in progress before the screencast, then the slide navigation buttons can be used to resume the slide show, or the browser tab can be selected to resume synchronized browsing.

Screencasting Best Practices, Tips and Pitfalls

Screencasting monitors an area of your screen for changes, then compresses any changed areas and sends them out to the room. In order to capture motion, this monitoring process happens many times each second and can be quite CPU intensive.

If your computer performance begins to lag while sending a screencast then you should choose a smaller area of your screen to broadcast. CPU resources required to screencast increase linearly with the area being screencast. You can monitor your CPU usage using Windows Task Manager (right click the Windows Task bar) or OS X Activity Monitor. If your average CPU usage is over 50% during a screencast, then you should choose a smaller screencast region.

Screencasting uses a special compression scheme optimized for software applications. It does not work well on photos or motion pictures such as DVDs in your media player. Attempting to stream a movie this way will result in blocky pictures and a very low frame rate, i.e. a jerky picture. A better solution for streaming movies is to use a dedicated streaming media server like Windows Media, Darwin or Helix. Alternately, upload a movie to one of the many streaming sites such as YouTube and use the Synchronized Browsing feature to direct everyone’s browser to the playback page for your uploaded movie.

Screencasting can also be very bandwidth intensive. The amount of bandwidth required depends on several factors: The size of the area being screencast, the amount of motion or change happening in this area, and the visual complexity of the contents of the screencast area.

For best results while screencasting:

  1. Use a second computer to receive the screencast so that you (the presenter) can see what everyone else in the room is seeing while you screencast.
  2. Use a high speed internet connection with upload speed > 500 Kbps.
  3. Limit the size of the screencast area to the minimum required area.
  4. Limit the changes in the screencast area — do not task-switch and bring other applications into the foreground in the screencast region as this causes bandwidth spikes.
  5. Do not screencast photos or movies. Use synchronized browsing to point to these resources on the web.
  6. Monitor your CPU usage and reduce the screencast area or upgrade your hardware if your CPU becomes overloaded.