3.7 KiB

Raw Permalink Blame History

Source Engine DEM format

This document applies to the version of TF2 as of July 1, 2015.
Demo Protocol v3.
Network Protocol v24.

DEM Format

The Source Engine DEM format at a high level:

[Demo Header]
[Command Header][Command Packet]
[Command Header][Command Packet]
...
[Command Header = dem_stop]
~fin

Demo Header

Type	Name	Description	Example
char[8]	Demo File Stamp	Demo file identifier.	"HL2DEMO"
int32	Demo Protocol	Demo protocol version.	3
int32	Network Protocol	Network protocol version.	24
char[260]	Server Name	Name of the server that recorded this demo.	"Team Fortress"
char[260]	Client Name	Name of the client that recorded this demo.	"SourceTV Demo"
char[260]	Map Name	Name of the map where this demo was recorded.	"cp_granary"
char[260]	Game Directory	Game directory relative to hl2.exe	"tf"
float32	Playback Time	Length of the demo in seconds.	9.05999947
int32	Playback Ticks	Length of the demo in ticks.	604
int32	Playback Frames	Length of the demo in frames.	151
int32	Signon Length	Length of the signon data in bytes.	640166

Note: Examples are from a short demo recording, hence the 9 second playback time.

Command Header

Type	Name	Description
int8	Command Type	Type of the next command packet.
int32	Tick	Game tick of the next command packet.

Command Type

Name	Value	Description
dem_signon	1	Signon packet. Same format as a network packet.
dem_packet	2	Network packet.
dem_synctick	3	Signals the client to sync clock to demo tick.
dem_consolecmd	4	Console command.
dem_usercmd	5	User input command.
dem_datatables	6	Network data tables.
dem_stop	7	Signals the end of demo messages.
dem_stringtables	8	Stringtables.

Command Packets

dem_signon/dem_packet

Type	Name	Description
democmdinfo_t	Demo Command Info	Describes view angles of the current point of view.
int32	Sequence Number In	Input sequence number of packet.
int32	Sequence Number Out	Output sequence number of packet.
RawData	Netpackets	RawData structure containing a series of netpackets.

dem_synctick

Command Packet of size 0 bytes.

dem_consolecmd

Type	Name	Description
char[1023]	Command String	Console command string of max length 1023 (including null char).

Note: A typo in the code that writes out console commands likely meant for a string of length 1024 (including null char).

dem_usercmd

dem_datatables

dem_stop