app.py

import cv2
import numpy as np
import torch
import base64
import asyncio
from collections import deque
from ultralytics import YOLO
from fastapi import FastAPI, WebSocket, WebSocketDisconnect
import uvicorn

# Load YOLO model with optimized settings
device = "cuda" if torch.cuda.is_available() else "cpu"
model = YOLO("yolov11s-face.pt").to(device)

# Constants for distance estimation
KNOWN_DISTANCE = 50  # cm
KNOWN_FACE_WIDTH = 14  # cm
REF_IMAGE_FACE_WIDTH = 120  # Reference face width in pixels at the known distance
FOCAL_LENGTH = (REF_IMAGE_FACE_WIDTH * KNOWN_DISTANCE) / KNOWN_FACE_WIDTH
SCALING_FACTOR = 2.0  # Adjust based on testing

# FastAPI initialization
app = FastAPI()

# Optimized tracking of previous detections using a deque
MAX_HISTORY = 10
detected_people_history = deque(maxlen=MAX_HISTORY)

DISTANCE_THRESHOLD = 30  # cm

@app.on_event("startup")
async def startup_event():
    print("\n🚀 WebSocket API is running on ws://0.0.0.0:7860/ws\n")

@app.websocket("/ws")
async def websocket_endpoint(websocket: WebSocket):
    """WebSocket for real-time face detection"""
    await websocket.accept()
    print("✅ Client connected")

    try:
        while True:
            frame_data = await websocket.receive_text()
            frame_bytes = base64.b64decode(frame_data)
            image_np = np.frombuffer(frame_bytes, np.uint8)
            frame = cv2.imdecode(image_np, cv2.IMREAD_COLOR)

            # Resize frame for faster inference
            h, w, _ = frame.shape
            resized_frame = cv2.resize(frame, (w // 2, h // 2))

            # Run YOLO model
            results = model(resized_frame, imgsz=320, half=True, verbose=False)

            new_people_data = {}
            change_detected = False
            person_id = 1
            frame_width = resized_frame.shape[1]

            for result in results:
                for box in result.boxes.data.tolist():
                    x1, y1, x2, y2, conf, _ = box[:6]
                    x1, y1, x2, y2 = map(int, [x1 * 2, y1 * 2, x2 * 2, y2 * 2])

                    if conf > 0.5:
                        center_x = (x1 + x2) // 2
                        face_width_pixels = x2 - x1

                        if center_x < frame_width // 3:
                            position = "Left"
                        elif center_x > 2 * frame_width // 3:
                            position = "Right"
                        else:
                            position = "Center"

                        estimated_distance = (
                            (FOCAL_LENGTH * KNOWN_FACE_WIDTH) / face_width_pixels
                        ) * SCALING_FACTOR if face_width_pixels > 0 else -1

                        new_people_data[f"person{person_id}"] = {
                            "distance_cm": round(estimated_distance, 2),
                            "position": position,
                        }

                        if detected_people_history:
                            prev_data = detected_people_history[-1].get(f"person{person_id}")
                            if (
                                not prev_data
                                or prev_data["position"] != position
                                or abs(prev_data["distance_cm"] - estimated_distance) > DISTANCE_THRESHOLD
                            ):
                                change_detected = True

                        person_id += 1

            if not detected_people_history or len(new_people_data) != len(detected_people_history[-1]):
                change_detected = True

            if change_detected:
                detected_people_history.append(new_people_data)
                await websocket.send_json({"people": new_people_data})
            else:
                await websocket.send_json({"people": []})

            await asyncio.sleep(0.05)

    except WebSocketDisconnect:
        print("❌ Client disconnected")
    except Exception as e:
        print(f"⚠️ Error: {e}")

if __name__ == "__main__":
    print("\n🔥 Starting WebSocket server...")
    uvicorn.run(app, host="0.0.0.0", port=7860)