Recording & Playback#

Genesis provides a flexible recording system for capturing simulation data. This enables data logging, visualization, video generation, and analysis of simulation results.

Overview#

The recording system consists of:

Recorder: Base class for processing simulation data
RecorderManager: Coordinates multiple recorders
FileWriters: Export data to files (CSV, NPZ, Video)
Plotters: Real-time visualization of data

Quick Start#

Recording Camera Video#

Record a video from a scene camera. Frames are captured automatically on each cam.render() call while recording is active.

import genesis as gs

gs.init()
scene = gs.Scene()
scene.add_entity(gs.morphs.Plane())
scene.add_entity(gs.morphs.Box(pos=(0, 0, 1), size=(1.0, 1.0, 1.0)))

cam = scene.add_camera(res=(640, 480), pos=(3, 0, 2), lookat=(0, 0, 0.5))

scene.build()

cam.start_recording()

for i in range(200):
    scene.step()
    cam.render()

cam.stop_recording(save_to_filename="simulation.mp4")

Recording Custom Data#

# Define what data to record
def get_robot_state():
    return {
        "position": robot.get_pos(),
        "velocity": robot.get_vel(),
        "joint_positions": robot.get_qpos(),
    }

# Start recording with recorder options
scene.start_recording(
    data_func=get_robot_state,
    rec_options=gs.recorders.NPZFile(
        filename="robot_data.npz",
        hz=100,  # Recording frequency
    ),
)

for i in range(1000):
    scene.step()
scene.stop_recording()

Real-time Plotting#

# Plot joint positions in real-time
scene.start_recording(
    data_func=lambda: robot.get_qpos(),
    rec_options=gs.recorders.MPLLinePlot(
        title="Joint Positions",
    ),
)

for i in range(1000):
    scene.step()
scene.stop_recording()

Components#

Recording Workflow#

Define data function: A callable that returns the data to record
Create recorder: Instantiate a recorder (FileWriter, Plotter, etc.)
Add to scene: Register the recorder with the scene
Start recording: Begin data capture
Run simulation: Execute simulation steps
Stop recording: Finalize and save data

Configuration#

All recorders share common options:

Option	Type	Description
`hz`	float	Recording frequency (samples/second)
`async_mode`	bool	Process data in background thread