Brain Imaging & Analysis Center

Showplay allows you to create an AVI video file of what appears on the screen while running a paradigm. To create an AVI, you first load your task file (PPF), then set the AVI options, then run your task.

Specifically, you should do the following:

• In the Showplay menu, select “Load parameter file” to load your task file
• In the Showplay menu, select “Create AVI file” to display a dialog box
• Set the parameters in the “SCreatAVI” dialog box
• In the Showplay menu, select “Run” to run your task
• Verify that the named AVI file has been created

In the CreateAVI dialog box, the following settings are required:

• Filename: the name of the AVI file to create (example: mytask.avi)
• Frame Pixels: the pixel dimensions of the AVI images
• Center: screen offset of where to grab frames from the screen, relative to center (0,0 is centered)
• Frames/TB: the maximum number of video frames per each TimeBase interval
• TB: the TimeBase interval in whole seconds (e.g. for 30frames/sec set TB=1, Frames/TB=30)

The specified timing parameters (TB and Frames/TB) give the maximum rate for saving video frames in the AVI. The actual rate may be less because new frames are only stored if the screen image has changed. Since each frame in a movie is time-stamped, omitting duplicate frames saves space without affecting the timing of the video during playback. So as long as TB and Frames/TB are at least as fast as the fastest image change in your PPF, the AVI created will be the same size (1 frame for every time the image changes).

AVI is a Windows video format with lots of different variants. CIGAL creates AVIs using the simplest uncompressed frame format, which can result in large video files. Many video editting and converting programs exist that you can use to reformat or modify AVI files created by CIGAL.

See Also:
ShowPlay Tutorial, ShowPlay Home, ShowPlay Manual, CIGAL Home, CIGAL Manual,