lerobot-find-cameras

Discover and test cameras connected to your system

The lerobot-find-cameras command detects OpenCV and Intel RealSense cameras, displays their capabilities, and captures test images.

Command

lerobot-find-cameras [CAMERA_TYPE] [OPTIONS]

Location: src/lerobot/scripts/lerobot_find_cameras.py

Overview

This utility helps you:

• Detect all connected cameras (OpenCV and RealSense)
• View camera capabilities (resolution, FPS, format)
• Identify camera indices and serial numbers
• Capture test images from all cameras
• Verify camera functionality before recording

Key Options

camera_type · str

Optional filter: opencv or realsense. If omitted, shows all cameras.

--output-dir · str · default: "outputs/captured_images"

Directory to save test images.

--record-time-s · float · default: "6.0"

Duration in seconds to capture test images.

Usage Examples

Detect All Cameras

lerobot-find-cameras

This displays all OpenCV and RealSense cameras with their metadata:

• Camera type and index/serial number
• Default resolution and FPS
• Video format (MJPG, YUYV, etc.)
• USB connection type

Detect Only OpenCV Cameras

lerobot-find-cameras opencv

Example output:

--- Detected Cameras ---
Camera #0:
  Type: OpenCV
  Id: 0
  Backend: V4L2
  Default stream profile:
    Width: 640
    Height: 480
    Fps: 30
    Format: MJPG
--------------------
Camera #1:
  Type: OpenCV
  Id: /dev/video4
  Backend: V4L2
  Default stream profile:
    Width: 1280
    Height: 720
    Fps: 30
    Format: YUYV
--------------------

Detect Only RealSense Cameras

lerobot-find-cameras realsense

Example output:

--- Detected Cameras ---
Camera #0:
  Type: RealSense
  Id: 123456789
  Name: Intel RealSense D405
  Firmware version: 5.15.0.2
  Usb type descriptor: USB 3.2
  Default stream profile:
    Width: 640
    Height: 480
    Fps: 30
    Format: RGB8
--------------------

Capture Test Images

lerobot-find-cameras --output-dir=./camera_test --record-time-s=10

This:

1. Detects all cameras
2. Connects to each camera
3. Captures images for 10 seconds
4. Saves images to ./camera_test/

Output files are named: {camera_type}_{camera_id}.png

Example:

outputs/captured_images/
├── opencv_0.png
├── opencv_2.png
└── realsense_123456789.png

Filter and Capture

lerobot-find-cameras opencv --output-dir=./opencv_test --record-time-s=5

Captures images only from OpenCV cameras for 5 seconds.

Camera Information

OpenCV Cameras

For each OpenCV camera, displays:

• Type: Always “OpenCV”
• Id: Camera index (0, 1, 2…) or device path (/dev/video4)
• Backend: Video capture backend (V4L2, MSMF, etc.)
• Default stream profile:
  • Width and height (pixels)
  • FPS (frames per second)
  • Format (MJPG, YUYV, H264, etc.)

RealSense Cameras

For each RealSense camera, displays:

• Type: Always “RealSense”
• Id: Camera serial number
• Name: Camera model (e.g., “Intel RealSense D405”)
• Firmware version: Current firmware version
• USB type descriptor: USB connection type
• Default stream profile:
  • Color stream resolution and FPS
  • Depth stream resolution and FPS (if available)

Common Use Cases

Identify Camera Indices for Recording

Before recording a dataset:

lerobot-find-cameras

Use the displayed indices in your recording configuration:

lerobot-record \
  --robot.cameras='{
    laptop: {type: opencv, index_or_path: 0, width: 640, height: 480, fps: 30},
    phone: {type: opencv, index_or_path: 2, width: 640, height: 480, fps: 30}
  }'

Find RealSense Serial Numbers

lerobot-find-cameras realsense

Use the serial number in your configuration:

lerobot-record \
  --robot.cameras='{
    realsense: {
      type: realsense,
      serial_number_or_name: 123456789,
      width: 640,
      height: 480,
      fps: 30
    }
  }'

Verify Camera Functionality

Test cameras before a long recording session:

lerobot-find-cameras --output-dir=./test --record-time-s=30

Check the saved images in ./test/ to verify:

• All cameras are detected
• Image quality is acceptable
• No USB bandwidth issues
• Correct camera orientation

Debug Camera Issues

If cameras aren’t detected:

1. Run without filter to see all devices:

   lerobot-find-cameras
   

2. Check if the camera appears but can’t connect:

   lerobot-find-cameras --record-time-s=2
   

   Look for connection errors in the output.

3. Try specific camera type:

   lerobot-find-cameras opencv
   lerobot-find-cameras realsense
   

Troubleshooting

No Cameras Detected

OpenCV cameras:

• Check USB connections
• Verify camera permissions (Linux: add user to video group)
• Try different USB ports
• Close other applications using cameras

RealSense cameras:

• Ensure pyrealsense2 is installed: pip install pyrealsense2
• On Linux, install udev rules: sudo apt install librealsense2-dkms
• Use USB 3.0 ports for best performance
• Update firmware using Intel RealSense Viewer

Camera Found But Can’t Capture Images

• Camera may be in use by another application
• Insufficient USB bandwidth (try disconnecting other USB devices)
• Driver issues (update camera drivers)
• Wrong USB port (use USB 3.0 for high-resolution cameras)

Wrong Camera Index

On Linux, camera indices can change. Use device paths instead:

# Find actual device path
ls -l /dev/video*

# Use path instead of index
lerobot-find-cameras  # Shows paths like /dev/video4

Or create udev rules for stable paths (see Camera Support).

Permission Denied (Linux)

# Add user to video group
sudo usermod -a -G video $USER

# Log out and back in for changes to take effect

Programmatic Usage

from lerobot.scripts.lerobot_find_cameras import find_and_print_cameras
from pathlib import Path

# Find all cameras
all_cameras = find_and_print_cameras(camera_type_filter=None)

# Find only OpenCV cameras
opencv_cameras = find_and_print_cameras(camera_type_filter="opencv")

# Find only RealSense cameras
realsense_cameras = find_and_print_cameras(camera_type_filter="realsense")

# Access camera metadata
for camera in all_cameras:
    print(f"Type: {camera['type']}")
    print(f"ID: {camera['id']}")
    if 'default_stream_profile' in camera:
        profile = camera['default_stream_profile']
        print(f"Resolution: {profile['width']}x{profile['height']} @ {profile['fps']} FPS")

See Also

• Camera Support - Camera configuration and usage
• lerobot-record - Record datasets with cameras
• Robot API - Robot and camera integration