README.md

[Blogpost] [🤗 Dataset] [🎮 Viewer]

Renders Counter-Strike 2 .dem demo files to per-player-round videos with synchronized frame-level metadata (keyboard inputs, mouse deltas, player position). Includes a browser-based viewer for exploring the output.

Built for Linux but can work on Windows with minimal modifications.

How it works

1. Parse (two-pass): extracts per-player spawn/death tick intervals and per-frame button inputs from the demo.
2. Render: generates a JSON action sequence, launches CS2 via Steam with the demo loaded, and lets the server plugin execute the action sequence.
3. Encode: streams raw TGA frames piped from CS2's movie output directory to ffmpeg (VAAPI HEVC), writing .mp4 files in real time.
4. Parquet: writes per-round metadata alongside each video.

Requirements

• Go 1.21+
• CMake 3.14+
• C++ compiler
• ffmpeg with VAAPI support (hevc_vaapi)
• Counter-Strike 2 installed via Steam

Building

1. Build the CS2 server plugin

Counter-Strike 2 updates break compatibility with the server plugin with the main branch built for version 1.41.6.5. See the branches for other game versions.

cmake ./cs2-server-plugin/ -B plugin-build -DCMAKE_BUILD_TYPE=Release
cmake --build plugin-build

Install the plugin:

./install-plugin.sh plugin-build/libserver.so

2. Build the renderer

cd dem-render && go build -o dem-render .

Usage

Steam must be running before invoking the renderer. Run dem-render --help for addional arguments. Arguments must come before the demo path in single-demo mode.

Single demo file

dem-render [flags] <path-to-demo.dem>

Produces one <uuid>.mp4 + <uuid>.parquet pair per player round. By default they land next to the dem-render binary; use --output to choose a directory.

Worker mode — batch directory

Process a directory of .dem files. Already-processed demos are skipped (a .log file marks completion).

dem-render worker --input /path/to/demos --output /path/to/output

Or via environment variables:

CS_INPUT_DIR=/path/to/demos CS_OUTPUT_DIR=/path/to/output dem-render worker

Each demo produces:

• <uuid>.mp4 + <uuid>.parquet per player round in the output directory
• <demoname>.log — success/error log for that demo

Output format

Each .parquet file contains one row with these columns:

Column	Type	Description
video_filename	str	Matching .mp4 filename
match_name	str	Demo filename stem
map	str	Map name (e.g. dust2)
steam_id	uint64	Player Steam ID
round_number	int	Round number
team	uint	0 = T, 1 = CT
num_frames	int	Frame count
fps	float	Framerate (default 48)
width, `height$	\text{int}	\text{Resolution} (\text{default} 1280 \times 720)
$total_time`	float	Clip duration in seconds
frame_data	list	Per-frame records (see below)

Each frame records: actions, mouse_x_delta, mouse_y_delta, position_x, position_y, position_z, rotation_yaw, rotation_pitch.

actions are a string of characters: W A S D J (jump) V (fall) C (crouch) R (walk) [ (left-click) or - for no action.

Viewer

Open viewer/index.html directly in your browser (requires the File System Access API).

Click ⚙ to select a local or remote dataset source.

Features:

• Match browser with map filter
• Synchronized video + action playback
• Mouse delta chart (yaw / pitch)
• XY position minimap

Credits

• demoinfocs-golang by Markus Walther — CS2/CSGO demo parser library used for all demo parsing
• CS Demo Manager by akiver — reference for server plugin implementation
• hl2sdk by AlliedModders — Source 2 SDK headers used by the server plugin
• nlohmann/json by Niels Lohmann — JSON library used by the server plugin to parse the action sequence