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
| 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
Command Packet of size 0 bytes.
dem_stringtables
Types Appendix
Vector
| Type |
Name |
Description |
| float32 |
x |
|
| float32 |
y |
|
| float32 |
z |
|
QAngle
| Type |
Name |
Description |
| float32 |
pitch |
|
| float32 |
yaw |
|
| float32 |
roll |
|
Split_t
| Type |
Name |
Description |
| int32 |
Flags |
|
| Vector |
View Origin |
|
| QAngle |
View Angles |
|
| QAngle |
Local View Angles |
|
| Vector |
View Origin 2 |
|
| QAngle |
View Angles 2 |
|
| QAngle |
Local View Angles 2 |
|
democmdinfo_t
| Type |
Name |
Description |
| Split_t[1] |
POV angles |
Array of Split_t. Constant length of 1 for demo protocol 3. |
RawData
| Type |
Name |
Description |
| int32 |
Size |
Size in bytes of the following data chunk. |
| uchar[Size] |
Data |
Data chunk of Size bytes. |
