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Computer Video Analysis with QuickCam:
Technical Information

Making movies using HyperCard and Make Crop Movie Stack

Before you start, the QuickCamVideo extension should be in the System Folder, and the QuickCam camera should be connected to the modem port (black and white versions, not color). It is also useful to have the QuickMovie and QuickPict applications on your hard drive.

In addition to the Make Crop Movie Stack, which contains the required XCMD's, you need either HyperCard or HyperCard Player and a Home stack. You may need to increase the memory used by HyperCard or HyperCard Player (select Get Info in the File menu, then set the desired memory in the dialog). The Home stack should be in the same folder as either the HyperCard application or the Make Crop Movie Stack. Be sure to make a backup copy of the Make Crop Movie Stack. Using HyperCard, it is very easy to make changes to stacks, and these changes take effect immediately.

When the stack opens, select Make Movie. You should see live video in a large rectangle on the card. Use the buttons in the upper left of the card to adjust the brightness. Then follow directions on the screen to crop the picture to the region of interest. After you make the cropping rectangle, you may drag it (click in the center and drag) or change its size (click in a corner and drag). When you are satisfied, select Make Movie.

Enter a name for the movie in the space provided. Each time you make a movie, it will be saved (in the folder containing the Hypercard application) with this name. If there is already a movie with this name, the old movie will be deleted. It is therefore important to give each movie a unique name if you plan to make several movies and analyze them later. Use the card buttons to select the length of time you want for the movie (2, 5, or 10 seconds).

When you select "prepare to grab", a dialog box opens (there are actually several dialogs---you may select one from the menu at the top of the box). You should make the following settings:

  1. In the "Compression" dialog, select Compressor--None, Depth--Best Depth.
  2. In the "Compression" dialog, enter the desired number of frames per second (don't use "best" if you want uniform time intervals).
  3. In the "Image" dialog, make additional brightness adjustment if necessary.
After you click "OK" you may start "grabbing" the movie by clicking the "grab now" button (wait until you see the live video in the cropped window). When the movie has been made, it is played back. You may then proceed to analyze it or go back and make another movie.

If the live video doesn't appear when you first open the stack, try running either QuickPict or QuickMovie to make sure that everything is working. Be sure the right version of QuickTime (2.1 or earlier) is installed. It sometimes helps to have QuickPict running when you open the HyperCard stack. If you also have a Color QuickCam, you may need to remove its extension from the System Folder.

If you have trouble getting the video to reappear after making different settings, it may be because you are not waiting long enough for the software to "catch up".

Analyzing movies

You may analyze the movie you just made by selecting "analyze movie" after the grabbed movie is played back. If you want to analyze a movie you made earlier, you select "analyze movie" from the first card of the stack and enter its name in the space provided. The movie must be in either the folder containing the HyperCard application or the folder containing the Make Crop Movie Stack.

To do the analysis, you should first enter the scaling factors which will be divided into the number of "ticks" (time) or "pixels" (horizontal and vertical position). For example, if you enter 600 (the number of "ticks" in one second) at the top of the time column, the recorded times will be in seconds.

Each time you click in the movie, the time for that frame and the position of the cursor are recorded in the table, and the movie advances to the next frame. The numbers in the table may then be copied into another program for analysis. If you have Vernier's Graphical Analysis, the button at lower left will open it for you; if you don't, you may select a different program in the dialog box which appears.

Making movies using QuickMovie

It is possible to make movies using the QuickCam application QuickMovie, but the timing intervals will be less uniform than those obtained with the HyperCard stack. You must have version 2 of this application; if the software supplied with the QuickCam is an earlier version, you may get an upgrade from Connectix.

To crop the video window, first select Angle of View--Zoomed from the Settings menu. Select Sizes--Other Size... in the Settings menu, and enter the desired dimensions, in pixels. Then select Camera Settings--Video Other... from the Settings menu, and make selections in the dialog boxes as described above.

Note that when you record the movie, you must use a screen button to stop recording rather than select the length of the movie in advance.



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