Miscellaneous stuff

Half-Life demo analysing

This is not directly a part of OpenDemo but it is demo-related.

Half-Life uses a demo format, that uses Quake1 DEM parts but also totally newly invented structures. To learn more about this demo format I started to write some simple Perl scripts to decode the demo files of version 1.1.0.1. I have not looked at any other version of Half-Life.

All these script will become part of LMPC in the future and can be fould now on the CVS tree of LMPC project page on SourceForge.

• The script del-hl.pl is a tiny Perl script, which can anaylse a Half-Life demo files and writes out a text file in the very good know LMPC text files syntax. The script can decode only very few basic messages but the overall structure with the directory and the possibility to concatanate several demo files is totally decoded.
• The more difficult games messages (which use delta encoding and the like) are described totally in a simple text file which comes with every Half-Life installation: Half-Life/valve/delta.lst. To learn how to handle this type of text file, I wrote the Perl module Delta.pm It is an object-oriented framework for reading parsing and writing delta files.
• The Perl script delta2xml uses Delta.pm and converts a delta file into an XML file with the same content but which is better parseble by standard (XML) tools.
• The Perl script delta2lst uses again the Perl module Delta.pm but reads in a delta file and writes out also a delta file. I used this tool to verify my programming. So I found out, that the original file delta.lst has 2 syntax errors but it seams, that Half-Life can ignore (like delta2lst too) these minor problems.

The next step is to use Delta.pm in the main script del-hl.pl to decode the more interesting game messages.

Please try out my scripts and test them on many demo files.