Add ICE server retrieval functionality for WebRTC

- Introduced a new utility module to fetch ICE servers from Twilio, enhancing connectivity options.
- Updated the WebRTC configuration in app.py to utilize the new get_ice_servers function for improved server management.

app.py

@@ -4,6 +4,7 @@ import numpy as np
 import streamlit as st
 from streamlit_webrtc import webrtc_streamer, WebRtcMode
 from src.opencv_utils import OpenCVUtils
+from utils.turn import get_ice_servers
 
 st.set_page_config(page_title="OpenCV Explorer", page_icon="🎨", layout="wide")
 
@@ -122,7 +123,7 @@ def video_frame_callback(frame: av.VideoFrame) -> av.VideoFrame:
 webrtc_streamer(
     key="opencv-explorer",
     mode=WebRtcMode.SENDRECV,
-    rtc_configuration={"iceServers": [{"urls": ["stun:stun.l.google.com:19302"]}]},
+    rrtc_configuration={"iceServers": get_ice_servers()},
     video_frame_callback=video_frame_callback,
     media_stream_constraints={"video": True, "audio": False},
     async_processing=True,

utils/turn.py

@@ -0,0 +1,19 @@
+import os, logging
+from twilio.rest import Client
+import streamlit as st
+
+logger = logging.getLogger(__name__)
+
+
+@st.cache_data
+def get_ice_servers():
+    try:
+        sid = os.environ["TWILIO_ACCOUNT_SID"]
+        token = os.environ["TWILIO_AUTH_TOKEN"]
+    except KeyError:
+        logger.warning("Twilio credentials not set; falling back to public STUN only.")
+        return [{"urls": ["stun:stun.l.google.com:19302"]}]
+    client = Client(sid, token)
+    # This will return both STUN and TURN servers from Twilio
+    token = client.tokens.create()
+    return token.ice_servers