359 lines
11 KiB
Python
359 lines
11 KiB
Python
"""
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FastAPI Web Application for Beacon Tracker Video Streaming
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This application reads JPEG frames from shared memory and streams them
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to web browsers via Server-Sent Events (SSE) or WebSocket (H.264 stream).
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"""
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from fastapi import FastAPI, WebSocket, WebSocketDisconnect, Request
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from fastapi.responses import HTMLResponse, StreamingResponse, Response
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from fastapi.staticfiles import StaticFiles
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from fastapi.templating import Jinja2Templates
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from shared_memory_reader import SharedMemoryFrameReader
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import asyncio
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import time
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import base64
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import json
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import os
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from typing import Set
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from contextlib import asynccontextmanager
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# Global state
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reader = None
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reader_lock = asyncio.Lock()
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last_frame_data = None
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last_frame_header = None
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frame_lock = asyncio.Lock()
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# Video streaming state
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active_websocket_clients: Set[WebSocket] = set()
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streaming_task = None
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streaming_active = False
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PIPE_PATH = '/tmp/beacon_video_stream'
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async def init_reader():
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"""Initialize the shared memory reader"""
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global reader
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async with reader_lock:
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if reader is None:
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try:
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reader = SharedMemoryFrameReader()
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print("Connected to shared memory successfully")
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except Exception as e:
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print(f"Failed to connect to shared memory: {e}")
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reader = None
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async def cleanup_reader():
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"""Clean up shared memory reader"""
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global reader
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async with reader_lock:
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if reader:
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reader.close()
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reader = None
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@asynccontextmanager
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async def lifespan(app: FastAPI):
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"""Lifespan context manager for startup and shutdown events"""
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# Startup
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await init_reader()
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print("FastAPI application started")
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yield
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# Shutdown
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await cleanup_reader()
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print("FastAPI application shutdown")
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# Create FastAPI app
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app = FastAPI(
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title="Beacon Tracker Video Stream",
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description="High-performance video streaming with WebSocket and SSE support",
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version="2.0",
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lifespan=lifespan
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)
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# Mount static files if directory exists
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if os.path.exists("static"):
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app.mount("/static", StaticFiles(directory="static"), name="static")
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else:
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print("Warning: 'static' directory not found, static files will not be served")
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# Templates
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templates = Jinja2Templates(directory="templates")
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@app.get("/", response_class=HTMLResponse)
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async def index(request: Request):
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"""Render the main page"""
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return templates.TemplateResponse("index.html", {"request": request})
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@app.get("/stream")
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async def stream_sse():
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"""
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Server-Sent Events stream endpoint
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Continuously sends JPEG frames to the client as they become available.
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"""
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async def generate():
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global reader
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# Initialize reader for this stream
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await init_reader()
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# Check again after init
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async with reader_lock:
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local_reader = reader
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if local_reader is None:
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yield f"data: {json.dumps({'error': 'Failed to connect to shared memory'})}\n\n"
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return
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consecutive_failures = 0
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max_failures = 100
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while True:
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try:
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async with reader_lock:
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if reader is None:
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yield f"data: {json.dumps({'error': 'Reader is None'})}\n\n"
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return
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# Run blocking read in thread pool
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result = await asyncio.to_thread(reader.read_frame)
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if result:
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header, jpeg_data = result
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consecutive_failures = 0
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# Encode JPEG as base64 for transmission
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jpeg_base64 = base64.b64encode(jpeg_data).decode('utf-8')
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# Create event data
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event_data = {
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'frame_number': header.frame_number,
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'timestamp_us': header.timestamp_us,
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'width': header.width,
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'height': header.height,
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'data_size': header.data_size,
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'jpeg': jpeg_base64
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}
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# Send as SSE event
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yield f"data: {json.dumps(event_data)}\n\n"
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# Update global state
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async with frame_lock:
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global last_frame_data, last_frame_header
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last_frame_data = jpeg_data
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last_frame_header = header
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else:
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consecutive_failures += 1
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if consecutive_failures >= max_failures:
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yield f"data: {json.dumps({'error': 'No frames available'})}\n\n"
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consecutive_failures = 0
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# Small delay to prevent busy waiting
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await asyncio.sleep(0.001) # 1ms - fast updates
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except Exception as e:
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print(f"Error in stream: {e}")
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yield f"data: {json.dumps({'error': str(e)})}\n\n"
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await asyncio.sleep(1)
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return StreamingResponse(
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generate(),
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media_type="text/event-stream",
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headers={
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"Cache-Control": "no-cache",
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"Connection": "keep-alive",
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"X-Accel-Buffering": "no"
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}
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)
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@app.get("/status")
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async def status():
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"""Get the current status of the stream"""
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await init_reader()
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async with frame_lock:
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if last_frame_header:
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return {
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'connected': True,
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'last_frame': last_frame_header.frame_number,
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'timestamp_us': last_frame_header.timestamp_us,
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'resolution': f"{last_frame_header.width}x{last_frame_header.height}"
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}
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else:
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return {
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'connected': reader is not None,
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'last_frame': None,
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'message': 'Waiting for frames...'
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}
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@app.get("/latest_frame")
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async def latest_frame():
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"""Get the latest frame as a JPEG image"""
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async with frame_lock:
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if last_frame_data:
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return Response(content=last_frame_data, media_type="image/jpeg")
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else:
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return Response(content="No frame available", status_code=404)
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async def stream_video_from_pipe():
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"""
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Read MPEG-TS video stream from named pipe and broadcast via WebSocket.
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This runs as a background task.
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"""
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global streaming_active
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print(f"Starting video stream reader from: {PIPE_PATH}")
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# Wait for pipe to be created by C++ application
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max_wait_time = 30 # seconds
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start_time = time.time()
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while not os.path.exists(PIPE_PATH):
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if time.time() - start_time > max_wait_time:
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print(f"ERROR: Pipe {PIPE_PATH} not found after {max_wait_time}s")
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return
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print(f"Waiting for pipe {PIPE_PATH}...")
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await asyncio.sleep(1)
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print(f"Pipe found: {PIPE_PATH}")
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try:
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# Open the named pipe in binary read mode
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print("Opening pipe for reading...")
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# Use asyncio to read from pipe
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streaming_active = True
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# Open pipe in non-blocking mode
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import fcntl
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pipe_fd = os.open(PIPE_PATH, os.O_RDONLY | os.O_NONBLOCK)
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print("Pipe opened successfully, starting stream...")
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chunk_size = 32768 # 32KB chunks for MPEG-TS
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while streaming_active and active_websocket_clients:
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try:
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# Read chunk from pipe
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try:
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data = os.read(pipe_fd, chunk_size)
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except BlockingIOError:
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# No data available, wait a bit
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await asyncio.sleep(0.001)
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continue
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if not data:
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print("No data from pipe, stream may have ended")
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break
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# Broadcast binary data to all connected WebSocket clients
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disconnected_clients = set()
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for client in active_websocket_clients.copy():
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try:
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await client.send_bytes(data)
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except Exception as e:
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print(f"Error sending to client: {e}")
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disconnected_clients.add(client)
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# Remove disconnected clients
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active_websocket_clients.difference_update(disconnected_clients)
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# Small delay to prevent overwhelming clients
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await asyncio.sleep(0.001)
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except Exception as e:
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print(f"Error reading from pipe: {e}")
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break
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os.close(pipe_fd)
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except FileNotFoundError:
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print(f"ERROR: Pipe {PIPE_PATH} not found")
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except Exception as e:
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print(f"ERROR in video streaming: {e}")
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import traceback
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traceback.print_exc()
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finally:
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streaming_active = False
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print("Video streaming stopped")
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@app.websocket("/ws/video")
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async def websocket_video_endpoint(websocket: WebSocket):
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"""WebSocket endpoint for video streaming"""
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global streaming_task, streaming_active
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await websocket.accept()
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print(f"Client connected to video stream: {id(websocket)}")
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# Add client to active set
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active_websocket_clients.add(websocket)
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# Start streaming task if not already running
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if not streaming_active:
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streaming_task = asyncio.create_task(stream_video_from_pipe())
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print("Started video streaming task")
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try:
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# Keep connection alive and handle client messages
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while True:
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# Wait for client messages (like ping/pong or control messages)
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try:
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data = await asyncio.wait_for(websocket.receive_text(), timeout=1.0)
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# Handle client messages if needed
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if data == "ping":
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await websocket.send_text("pong")
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except asyncio.TimeoutError:
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# No message received, continue
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continue
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except WebSocketDisconnect:
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print(f"Client disconnected from video stream: {id(websocket)}")
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except Exception as e:
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print(f"WebSocket error: {e}")
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finally:
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# Remove client from active set
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active_websocket_clients.discard(websocket)
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# Stop streaming if no more clients
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if not active_websocket_clients:
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streaming_active = False
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print("No more clients, stopping stream")
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@app.get("/health")
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async def health():
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"""Health check endpoint"""
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return {
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"status": "healthy",
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"active_websocket_clients": len(active_websocket_clients),
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"streaming_active": streaming_active,
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"pipe_exists": os.path.exists(PIPE_PATH)
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}
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if __name__ == '__main__':
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import uvicorn
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print("Starting FastAPI server on http://0.0.0.0:5000")
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print(f"Video stream will be available at ws://0.0.0.0:5000/ws/video")
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uvicorn.run(
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app,
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host='0.0.0.0',
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port=5000,
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log_level='info',
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access_log=True
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)
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