Creating an MPEG from DX

Getting Started

To allow access to all executables you will need to create an MPEG movie you must add the following to your path:

On HP Lab Machines: ~tgd/cs450/bin

In order to do this, add the statement:

On HP Lab Machines: set path=($path ~tgd/cs450/bin)

to your .cshrc file. Then, you must source your .cshrc file (in order for the changes to take effect in your current login session) by executing the command:

source .cshrc

There are a number of files in the directory you have just added to your path that will help you MPEG encode your animation. They are described below. All of the commands mentioned below should work exactly as specified below after this step is performed. This step must only be performed the first time once.

Preparing Frames

In order to MPEG encode your animation, you need to store your frames in separate files. In order to do this, connect the MPEGmac module in your program as seen below:

In order to download this module, click here. When the window showing the file opens, use the "save as" option to put the file in your directory. Once it is there, move the file to your ".DXmacros" directory so that the macro is loaded into DX automatically upon startup. [If you do not do this before you start DX, the macro will not appear in DX. You can then use the "load macro" option in the DX user interface (under the "File" heading) to load the macro.] A new entry named "Mpeg" will appear in the "Categories" menu of DX. If you select this, you will see "MPEGmac" listed in the tools window. Select this and hook it up as shown in the example above.

The MPEGmac macro will automatically write out the images in your animation in the correct file format and with the correct names. There are a couple of points to be careful about.

Creating an MPEG movie

The script mpeg.script is provided for you in order to help you create an MPEG movie. The usage syntax for it is:


This script assumes that the current working directory contains a set of files created by MPEGmac with the names image.000.rgb, image.001.rgb, etc. It also assumes that each rgb file has a corresponding size file image.000.size etc. These are all written by MPEGmac. The script then counts the number of such files and constructs a file called dx.param. This is a parameter file for the MPEG encoder. It indicates such things as the starting and ending frame file names and the tradeoff between compression and image quality. The script then executes a program called mpeg_encode, which will construct the MPEG file and save it with the name image.mpg.

Viewing an MPEG Movie

You can view an MPEG animation by typing:

mpeg_play file.mpg.

For example, you can view the ~tgd/cs450/sample.mpg animation on the HP system by typing:

mpeg_play ~tgd/cs450/sample.mpg

Implementation Details

Normally, the process of making an mpeg movie is a little more complicated. It involves editing a parameter file in which you have to specify a complex set of parameters as well as describing the file names of the images and their format. After this, the command mpeg_encode has to be executed in order to create the MPEG movie. The program you are using to create your MPEG movie does all of these steps for you. There is a template parameter file, in which the values you give as arguments above are automatically inserted. The file is written out as dx.param, and is then used by the mpeg_encode command to create your MPEG movie. If you want to experiment with different MPEG encoding settings, you can edit dx.param and invoke mpeg_encode yourself using

mpeg_encode dx.param

The MPEGmac macro makes sure that all of the files are written out in a certain format (RGB) and with very specific file names. The file names are important because the parameter file used by the mpeg_encode command as written requires this specific format. This is not required, but makes the process somewhat easier to implement.

Please send any questions or comments to:

Tom Dietterich :