2.2.1 Construction of the animation

As detailed in Section 2.1, a series of numbered images were generated by the network. These are in AVS's .X format, and so must first be converted to a useful format, such as SGI's .SGI (or .RGB) format. This was acheived with the use of the MICA utility, and a command such as:

mica -to sgi ass2d-1.*.x

which converted the files ass2d-1.001.x - ass2d-1.020.x to ass2d-1.001.sgi - ass2d-1.020.sgi.

The next step was to assemble these images into a playable animation. This was acheived with the use of the MAKEMOVIE utility, and a command such as:

makemovie -o ass2d-1.mov -f qt -c qt_anim -r 4 -s 768,576 -b ass2d-1.*.sgi

which created the movie file ass2d-1.mov from the image files. The options passed to MAKEMOVIE are now explained.

-o ass2d-1.mov

specifies the output file, in this case, ass2d-1.mov.

-f qt

specifies the output movie format, in this case, Quicktime.

-c qt_anim

specifies the compression to be used in the output movie format, in this case, Quicktime animation compression (as opposed to Quicktime video compression, which is less appropriate to this kind of animation).

-r 4

specifies the number of input images to display in the output movie per second. In this case, four input frames will be displayed per second, that is, each image will be on the screen for a quarter of a second. This makes the 20 frame animation 5 seconds long, and yet still acceptably smooth.

-s 768,576

specifies the resolution of the output movie, in this case, PAL resolution, 768x576. If the input images are smaller than this resolution (as they were), they will be scaled as much as possible while maintaining their aspect ratio, and black borders will be added to the horizontal or vertical edges as needed⁵.

-b

specifies that the images are to be blurred by a 1-2-1 convolution in the time dimension, which helps to reduce flickering when played back through video. This option makes no discernible difference when viewing on a computer workstation.

In a similar fashion, the slow-motion section is obtained from ass2d-2.001.x - ass2d-2.020.x to the movie file ass2d-2.mov.

Finally, the MOVIEMAKER utility was used to combine the two movies ass2d-1.mov and ass2d-2.mov into one movie file, ass2d.mov, complete with titles.