campi server

Author: Mohamed Debbagh (mohas95)

This project creates a simple flask + openCV server for streaming video and accessing camera frames of standard V4l2 protocol usb cameras and luxionus depthai cameras on a rasberry pi (or linux/debian system).

Supports live MJPEG video streaming, lossless PNG snapshots, and raw NumPy frame data for scientific/computer-vision clients.

In the project pipeline

• RTSP serving
• Computer vision outputs(Particularly from DepthAI cameras)

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Features

• Stream live video feed over HTTP (/video_feed)
• Get lossless PNG-encoded snapshots (/lossless_frame)
• Get raw NumPy frame data (/raw_frame)
• Query and change camera configuration (/current_config, /configure)
• List available devices, codecs, resolutions, and FPS (/devices)
• Graceful shutdown (releases camera device when service stops)
• Create custom pipelines for depthai cameras
• Works with browsers, Python clients, or custom UIs

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Installation

Requirements

• Python 3.9+
• OpenCV (cv2)
• NumPy
• Flask
• Gunicorn (for production with systemd)

Install dependencies

sudo apt update
sudo apt install python3-opencv python3-numpy python3-flask python3-pip v4l-utils guinicorn

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Optional

• Raspberry pi auto hotspot script (Useful for connecting pi to network)

cd
curl "https://www.raspberryconnect.com/images/scripts/AccessPopup.tar.gz" -o AccessPopup.tar.gz
tar -xvf ./AccessPopup.tar.gz
cd AccessPopup
sudo ./installconfig.sh
# Follow installer script prompts

Running the Server

Development Mode (Flask backend)

git clone https://github.com/mohas95/pi_cam_server.git
cd pi_cam_server
python3 app.py

Production Mode (gunicorn backend)

one time run (not as a service)

git clone https://github.com/mohas95/pi_cam_server.git
cd pi_cam_server
gunicorn --workers 1 --threads 4 --timeout 120 --bind 0.0.0.0:5000 app:app

Systemd service Example (run on system boot)

Save as /etc/systemd/system/campi.service:

[Unit]
Description=Campi Server using Flask and Gunicorn
After=network.target

[Service]
User=pi
WorkingDirectory=/home/pi/pi_cam_server
ExecStart=/usr/bin/gunicorn --workers 1 --threads 4 --timeout 120 --bind 0.0.0.0:5000 app:app
Restart=always

[Install]
WantedBy=multi-user.target

Enable and start:

sudo systemctl daemon-reload
sudo systemctl enable campi.service
sudo systemctl start campi.service

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API Endpoints

1. Live Video Stream

GET /video_feed

• Returns MJPEG stream (multipart/x-mixed-replace)
• Usable directly in tags or OpenCV clients

2. PNG Snapshot (Lossless)

GET /lossless_frame

• Returns a single lossless PNG-encoded frame
• Content-Type: image/png
• Good for one-off snapshots or analysis

3. Raw Frame (NumPy buffer)

GET /raw_frame

• Returns raw BGR bytes (application/octet-stream)
• Metadata in response headers:
  • X-Height → image height
  • X-Width → image width
  • X-Channels → number of channels (3 for BGR)
  • X-Dtype → NumPy dtype (e.g., uint8)

Client can reconstruct with:

frame = np.frombuffer(resp.content, dtype=np.uint8).reshape(height, width, channels)

4. Current Configuration

GET /current_config

• returns

{
  "device_id": "/dev/video0",
  "codec": "MJPG",
  "width": 1280,
  "height": 720,
  "fps": 30
}

5. List Devices

GET /devices

• Returns all available devices, codecs, resolutions, and FPS.
• Example response:

{
  "/dev/video0": {
    "device": "C922_Pro_Stream_Webcam",
    "formats": [
      {
        "codec": "MJPG",
        "desc": "Motion-JPEG",
        "resolutions": [
          {"resolution": "1920x1080", "fps": [30.0]},
          {"resolution": "1280x720", "fps": [30.0]}
        ]
      }
    ]
  }
}

6. Configure Camera

POST /configure

• Re-initializes the camera with new settings
• Content-Type: application/json
• example of configuration to send:

{
  "device_id": "/dev/video0",
  "codec": "MJPG",
  "resolution": "1280x720",
  "fps": 30
}

• Returns { "status": "ok" } if successful

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Change log

0.0.1

• start integration with depthai cameras
• access control to prevent pipeline breaking or conflicting stream access
• fixes to initialization protocol
• custom pipeline builder integrations for depthai cameras
• change device identifier to device_id rather than device