Bootstap WebRTC PC connection using aiortc

.vscode/settings.json

@@ -0,0 +1,3 @@
+{
+  "python.pythonPath": "/Library/Frameworks/Python.framework/Versions/3.7/bin/python3"
+}

core/README.md

@@ -1,3 +1,17 @@
 # Camlio Core
 
 Core module responsible for processing webcam stream
+
+## Start engine
+
+```bash
+python engine.py --port 8081 --cert-file secrets/server.crt --key-file secrets/server.key --video_device_index=4
+```
+
+### FAQs
+
+1. How to find the webcam index?
+
+```bash
+ffmpeg -f avfoundation -list_devices true -i ""
+```

core/engine.py

@@ -0,0 +1,101 @@
+import argparse
+import asyncio
+import json
+import logging
+import os
+import platform
+import ssl
+
+import aiohttp_cors
+from aiohttp import web
+from aiortc import RTCPeerConnection, RTCSessionDescription
+from aiortc.contrib.media import MediaPlayer
+
+from video_stream import CamlioVideoStreamTrack
+
+ROOT = os.path.dirname(__file__)
+
+
+async def offer(request):
+    params = await request.json()
+    offer = RTCSessionDescription(sdp=params["sdp"], type=params["type"])
+
+    pc = RTCPeerConnection()
+    pcs.add(pc)
+
+    @pc.on("iceconnectionstatechange")
+    async def on_iceconnectionstatechange():
+        print("ICE connection state is %s" % pc.iceConnectionState)
+        if pc.iceConnectionState == "failed":
+            await pc.close()
+            pcs.discard(pc)
+
+    # open media source
+    if args.play_from:
+        player = MediaPlayer(args.play_from)
+    else:
+        player = None
+
+    await pc.setRemoteDescription(offer)
+    for t in pc.getTransceivers():
+        if t.kind == "audio" and player and player.audio:
+            pc.addTrack(player.audio)
+        elif t.kind == "video":
+            pc.addTrack(CamlioVideoStreamTrack(args.video_device_index))
+
+    answer = await pc.createAnswer()
+    await pc.setLocalDescription(answer)
+
+    return web.Response(
+        content_type="application/json",
+        text=json.dumps(
+            {"sdp": pc.localDescription.sdp, "type": pc.localDescription.type}
+        ),
+    )
+
+
+pcs = set()
+
+
+async def on_shutdown(app):
+    # close peer connections
+    coros = [pc.close() for pc in pcs]
+    await asyncio.gather(*coros)
+    pcs.clear()
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser(description="Camlio engine")
+    parser.add_argument("--video-device-index",
+                        help="Index of video camera", type=int, default=0)
+    parser.add_argument("--cert-file", help="SSL certificate file (for HTTPS)")
+    parser.add_argument("--key-file", help="SSL key file (for HTTPS)")
+    parser.add_argument(
+        "--play-from", help="Read the media from a file and stream it."),
+    parser.add_argument(
+        "--port", type=int, default=8080, help="Port for HTTP server (default: 8080)"
+    )
+    parser.add_argument("--verbose", "-v", action="count")
+    args = parser.parse_args()
+
+    if args.verbose:
+        logging.basicConfig(level=logging.DEBUG)
+
+    if args.cert_file:
+        ssl_context = ssl.SSLContext()
+        ssl_context.load_cert_chain(args.cert_file, args.key_file)
+    else:
+        ssl_context = None
+
+    app = web.Application()
+    cors = aiohttp_cors.setup(app, defaults={
+        # Allow all to read all CORS-enabled resources from
+        # *.
+        "*": aiohttp_cors.ResourceOptions(expose_headers="*",
+                                          allow_headers="*"),
+    })
+    app.on_shutdown.append(on_shutdown)
+    cors.add(
+        app.router.add_route("POST", "/offer", offer)
+    )
+    web.run_app(app, port=args.port, ssl_context=ssl_context)

core/video_stream.py

@@ -0,0 +1,22 @@
+import cv2
+import numpy
+from aiortc import VideoStreamTrack
+from av import VideoFrame
+
+
+class CamlioVideoStreamTrack(VideoStreamTrack):
+    def __init__(self, video_device_index):
+        super().__init__()
+        self.video_capture = cv2.VideoCapture(video_device_index)
+
+    async def recv(self):
+        try:
+            pts, time_base = await self.next_timestamp()
+            ret, raw = self.video_capture.read()
+
+            frame = VideoFrame.from_ndarray(raw, format="bgr24")
+            frame.pts = pts
+            frame.time_base = time_base
+            return frame
+        except Exception as e:
+            print(e)