Creation of MPEG's and "Pseudo Film"

Brought to you by
John B. Schneider, Patrick J. Flynn, and Kurt L. Shlager

Step 1: Create the raw files using circle.f. Here is a shell script, called run-circle, that will run the program for you using all the values that were used to generate the graphics presented here. The output will be 220 raw frame files, each of which contains the fields measured over a 140 by 140 portion of the computational domain. Note that a subdirectory named Output must be created before you run this shells script (this subdirectory is where all the raw files go).

Step 2: Once all the raw files are available, they must be converted to the appropriate graphics format using rw2pnm.f or rw2pnm.c. Here is shell script, named gen-frames that will do this for you. This shell script should be executed from the Output subdirectory. BE CAREFUL! Since this shell script generates grayscale, one-sided color, and two-sided color output for each of the 220 raw files, the net results is huge (approximately 33 MB). If you want less output, you can chop out something from the shell script or get rid of some of the raw files (but remember they must be consecutively numbered).

Step 3: The MPEG files can now be constructed using the mpeg_encode utility. The shell script gen-mpeg will do this for you. This shell script should be run from the directory above the Output subdirectory. To obtain the proper output, three "template files" are used by mpeg_encode. They are as follows:

Parameter file for grayscale output. For this to work properly, an additional "filter" is needed to convert from PGM format to PPM format (this is only necessary in the case of grayscale files). You need not do the conversion prior to running mpeg_encode, but the utility pgmtoppm must be available on your system. If you do not have this routine, you can either write a conversion routine yourself (and we don't advocate that), or grab one from the pbmplus or netpbm suites of routines.

Parameter file for one-sided output.

Parameter file for two-sided output.

You can also grab the sample parameter file that was mentioned in the paper by clicking here. This file should work well with "typical" animations.

Step 4: If, for some reason, you want to create "pseudo film" like shown at the top of this page, you can use the shell script create-film to do this. However, before you can run the script, you will need to grab a couple of "building blocks." The file guide-white.ppm is used to construct the film "guides" along the top and bottom while the file line.ppm is used to separate the frames. Actually, six output files are produced by create-film. Three PPM files contain only three frames and the frames are four times larger than the images shown here. The other three output files are GIF images corresponding to the output example output shown previously. Once again, this output relies on routines that can be found in the pbmplus or netpbm suites of routines.

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John B. Schneider, schneidj@eecs.wsu.edu
Patrick J. Flynn, flynn@ee.eng.ohio-state.edu
Kurt Shlager, kurt.shlager@lmco.com