How To Make Doom .lmp Demo's

                           Last Change: 28/Jun/96

                    By Ian Mapleson (mapleson@gamers.org)

Acknowledgements: bontchev@informatik.uni-hamburg.de (Vesselin Bontchev)
                    - for info on time limit and net game reminder.


First of all, what IS a .lmp Doom demo.?

In Doom, Ultimate Doom and Doom II, it is possible to record a playing session;
ie. you can save to a file exactly what you do during a chosen episode and
level/map (these demo files have a .lmp suffix). This file can then be played
back later so that you can sit back and watch exactly what you did. The file
itself does NOT contain any graphics images. The demo file merely records which
keys get pressed and also the various mouse movements. However, there are
certain key actions that are NOT recorded. These include using the ESC key to
bring up the main menu and any actions taken using that menu. Also, you may
find that using the mouse is not _quite_ as smooth as when playing normally -
this is probably due to the overhead of having to record the various mouse
movements as you play. One annoying thing is that the game _will_ record any
use of the PAUSE key, so make sure you don't use it when recording a lmp file.


Note: As a general rule, demos recorded on one version of Doom (say v1.2)
      will not work run properly on another version of Doom (say 1.666).

This is because of changes in maps between versions, changes in the rules
governing monster behaviour, differences in the format conventions between
versions, etc. Some of these things can be worked around by a little bit of
hacking (post to rgcd.editing for more info).


HOW TO RECORD A .lmp DEMO.:

All the commands shown here should be typed whilst in the same directory which
contains your Doom files.

The general command for recording a .lmp demo is as follows:-

  doom -devparm -warp <ep> <lv> -skill <num> -record <file> [-respawn]

Where:

   <ep>    is 1 for the shareware version, or 1 to 3 for the registered version,

   <lv>    is 1 to 9 (level 9 is always the secret level, although the
           actual from which you get _to_ a secret level is never level 8),

   <num>   is 1 to 4 for v1.1, or 1 to 5 for v1.2,

   <file>  is the name of the file that the demo is to be saved to. NOTE:
           the '.lmp' suffix MUST NOT be included in the file name. If you
           _do_ include it, Doom will not be able to find the file!

For Doom II: I should imagine that the '<ep> <lv>' combination would be
replaced by a single number from 1 to 32 when making recordings in Doom II. You
might have to include a preceeding zero for level numbers below 10 (ie. use 01
to 09). Try it and see.

The option '-respawn' may be included; this makes the bad guys regenerate
each time they get killed and also makes them faster, more accurate with
their weapons/fire balls, enables them to shoot more often, etc. Thus,
running Doom on skill level 4 with the -respawn option gives a level of
difficulty kinda half way between 4 and 5 (where 5 is Nightmare mode).

If you start the game in Nightmare mode, the '-respawn' option isn't needed.

Note: there is a time limit in versions of Doom <= 1.2 of about 15 to 17
minutes. It depends on exactly what you're doing as to how fast the demo buffer
file fills up. There is no limit in v1.666 (and higher) of Doom; the demo will
simply terminate if the buffer space is exceeded, but that would be after a lot
of recording. In v1.666, I understand one can also specify how much space to
allocate to the demo recording buffer. Precise info on this will be in the
README file that comes with the game.


Demo making examples...

Example 1:

(this won't work on Shareware Doom because of the episode and level used, so
try something like episode 1 level 4 if you're a Shareware user...)

Record a demo of the Cyberdemon (Episode 2 Level 8) on skill level 3, saving
it to a file called 'mydemo1.lmp'...

   doom -devparm -warp 2 8 -skill 3 -record mydemo1
                                                       .
                                                      /|\
                                                       |
                                            Note! NO SUFFIX!

Example 2:

Record a demo of The Unholy Cathedral (Ep 3, lev 5) on Ultraviolence with
respawning to a file called 'e3l5resp.lmp'...

   doom -devparm -warp 3 5 -skill 4 -record e3l5resp -respawn


Example 3:

Record a demo of the secret level on Epiosode 1 (The Military Base) in
Nightmare mode, to a file called 'e1l9ntmr.lmp'...

   doom -devparm -warp 1 9 -skill 5 -record e1l9ntmr


PLAYING BACK THE DEMO:

The general command to play back a demo file is:

   doom -playdemo <file name>

Where <file name> is the name of the .lmp demo file, BUT WITHOUT THE SUFFIX!

If the '-respawn' option was used to make the demo, it must be used when playing
back the demo (thus, the option is NOT needed for Nightmare mode demo's).

Thus, for the three examples above, they would be played back with the
following commands respectively:

   doom -playdemo mydemo1

   doom -playdemo e3l5resp -respawn

   doom -playdemo e1l9ntmr


When making a demo recording, you can save it at anytime by pressing Q. The
demo also terminates when you get to the end of the level. If you die, then
press Q to save. F10 will quit without saving. I understand that versions
after v1.2 will also record the end-of-level screen so that you can see what
the scores were.


USING THE DEVPARM PARAMETERS BUT NOT TO MAKE A DEMO.:

You can use the various devparm parameters to start a game off from a
particular episode and level _without_ making a .lmp recording. This is done
by not including the '-devparm' option, ie.:

   doom -warp <ep> <lv> -skill <num> [-respawn]

The various parameters are just the same as before.


Other notes:

Trying to use ANY of the cheats when making a .lmp demo, will HALT the demo!
One thing to remember, therefore, is that since the demo is going to STOP at
the end of the level, there is no need for you to 'conserve' ammo for the
next level.

However, the PAUSE key _does_ get recorded during demo making, so try and
make sure you don't get interupted by anything during play.

You cannot save your position during a demo recording session. Pity... :(
At least not in v1.2 anyway and I don't think this has changed in later
versions. Correct me if I'm wrong.

Anyway, that's all I can think of at the moment.

Have fun! :)

Ian.

The Doom Help Service (DHS).

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Tel: (+44) 01772 893297, Fax: (+44) 01772 892913 | Doom: mapleson@gamers.org
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