Grazza
Quaerere Verum
Posts: 9751
Registered: 07-02 |
This post answers some frequently-asked questions about the basics of demo-recording and demo-watching.
New (2007): Please see this thread for information on an easier way to watch demos. This works with most demos recorded with the "vanilla" engines, Boom, MBF, etc.
A demo is not a video clip. It is a recording of the player's actions. The original games and most ports support the recording and playing back of demos. In general, demos only play back with the same engine (exe) that they were recorded with (but see the red text below). You also need to make sure that any wads required (iwad or pwad) are the same version as was used to record, and haven't been modified in any way. So if you have for some reason rebuilt the nodes for your iwads, you'll need to reinstall them from the original disks, and if necessary patch them up to version 1.9, or else restore them from a backup. Note also that Doom95 cannot be relied upon to play back Doom2 demos (it works well with Ultimate Doom demos though).
To watch a demo, you put "-playdemo" in the command-line, followed by the name of the demo file. Thus:
doom2 -playdemo 30nm2956
plays back the demo named 30nm2956.lmp using doom2.exe and the doom2 iwad.
To play back a pwad demo, you need to include the pwad in the command line, as normal, using "-file". Example:
prboom-plus -file hr.wad hrmus.wad -playdemo 30hr2843
plays back the demo named 30hr2843.lmp using prboom-plus, and Hell Revealed.
Dragging and dropping also works with prboom-plus - drag and drop the demo file (and any pwads and dehs needed) onto an icon for prboom. Note that the default iwad it uses is Doom2.wad. If you need to use a different iwad, then you need to specify it with "-iwad" in the command line, or else to make an icon to another copy of prboom-plus that has a different iwad (simplest way: put a copy in a folder where there is a copy of doom.wad {or one of the Final Doom iwads, whatever} but no doom2.wad).
To record a demo, you need to put "-record" in the command line, followed by the name you want the demo to have. You will also need to specify a skill level and warp to the level on which you want to begin. Example:
eternity -file av.wad -warp 01 -skill 5 -record an01-xxx
records a demo temporarily named an01-xxx.lmp using Eternity, on Nightmare skill starting on map01 of Alien Vendetta.
In some ports, compatibility modes have been implemented that enable them to play back demos from some other ports. Most notable is Prboom-plus, which will play back demos from the original games, Boom, MBF (and some others) with a high degree of success. (A failure is known as a "desync", and generally means the player starts acting crazily, shooting walls, and most often dying.) Eternity will reliably play back demos from the original games and MBF demos, while Chocolate Doom will handle "vanilla" demos well.
Prboom-plus can also be used to record demos in several formats. See the documentation and this post for details.
The majority of demos you'll find online will play back with Prboom-plus. This program will normally autodetect the demo format if it is one that it can play back. There should generally be a textfile accompanying a demo. Read this to see if you need to use a different port to watch the demo, or if you need to "force" a complevel via the command line (it is very rare to need to do this). The most common other ports for recording are Legacy and Zdoom. In each case, you will need to make sure you have the same version of the port that was used to record it. (A Zdoom demo from version 2.0.47, for instance, is quite unlikely to play back with 2.0.63a, etc.)
Useful links:
Andrey Budko's PrBoom-plus (also: prboom-plus sourceforge site). This comes in software and OpenGL "flavours" - use either prboom.exe or glboom.exe.
Eternity
Compet-n (accepts "world record" demos on the iwads and selected pwads, as long as they are recorded with the original DOS exes)
newly incoming compet-n demos
Doomed Speed Demos Archive (click on "Single Player" to get a listing of pwads for which there are SP demos; DSDA accepts almost all demos on any pwad)
Doomworld Demos Forum (you are here! Discussion, recording projects, demos, tips, and anything else to do with demos and speedrunning)
Doom2.net (lots of info, especially on deathmatch)
Archive of Compet-n, DSDA and Pdang demos
Heretic-N
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10-13-03 06:44 
