fix usb device update behavior

src/auracast/server/multicast_frontend.py

@@ -66,7 +66,12 @@ if audio_mode in ["Webapp", "USB"]:
         if default_input not in input_options:
             default_input = input_options[0]
 
+        col1, col2 = st.columns([3, 1], vertical_alignment="bottom")
+        with col1:
             selected_option = st.selectbox("Input Device", input_options, index=input_options.index(default_input))
+        with col2:
+            if st.button("Refresh"):
+                st.rerun()
         # We send only the numeric/card identifier (before :) or 'default'
         input_device = selected_option.split(":", 1)[0] if ":" in selected_option else selected_option
     else:
@@ -76,23 +81,22 @@ if audio_mode in ["Webapp", "USB"]:
 
     if stop_stream:
         try:
-            r = requests.post(f"{BACKEND_URL}/stop_audio")
-            if r.status_code == 200:
+            r = requests.post(f"{BACKEND_URL}/stop_audio").json()
+            if r['was_running']:
                 st.success("Stream Stopped!")
             else:
-                st.error(f"Failed to stop: {r.text}")
+                st.success("Stream was not running.")
         except Exception as e:
             st.error(f"Error: {e}")
 
     if start_stream:
         # Always send stop to ensure backend is in a clean state, regardless of current status
-        try:
-            requests.post(f"{BACKEND_URL}/stop_audio", timeout=5)
-        except Exception:
-            # Ignore connection or 500 errors – backend may not be running yet
-            pass
+        r = requests.post(f"{BACKEND_URL}/stop_audio").json()
+        if r['was_running']:
+            st.success("Stream Stopped!")
+
         # Small pause lets backend fully release audio devices before re-init
-        import time; time.sleep(0.7)
+        import time; time.sleep(1)
         # Prepare config using the model (do NOT send qos_config, only relevant fields)
         q = quality_map[quality]
         config = auracast_config.AuracastConfigGroup(

src/auracast/server/multicast_server.py

@@ -3,6 +3,7 @@ import os
 import logging as log
 import uuid
 import json
+import sys
 from datetime import datetime
 import asyncio
 import numpy as np
@@ -14,9 +15,18 @@ from aiortc import RTCPeerConnection, RTCSessionDescription, MediaStreamTrack
 import av
 import av.audio.layout
 import sounddevice as sd  # type: ignore
-from typing import List, Set
+from typing import Set
 import traceback
 
+
+PTIME = 40 # TODO: seems to have no effect at all
+pcs: Set[RTCPeerConnection] = set()      # keep refs so they don’t GC early
+
+class Offer(BaseModel):
+    sdp: str
+    type: str
+
+
 # Path to persist stream settings
 STREAM_SETTINGS_FILE = os.path.join(os.path.dirname(__file__), 'stream_settings.json')
 
@@ -38,6 +48,7 @@ def save_stream_settings(settings: dict):
     except Exception as e:
         log.error('Unable to persist stream settings: %s', e)
 
+
 app = FastAPI()
 
 # Allow CORS for frontend on localhost
@@ -151,9 +162,12 @@ async def stop_audio():
             await asyncio.gather(*close_tasks, return_exceptions=True)
 
         # Now shut down the multicaster and release audio devices
+        running=False
         if multicaster is not None:
             await multicaster.stop_streaming()
-        return {"status": "stopped"}
+            running=True
+
+        return {"status": "stopped", "was_running": running}
     except Exception as e:
         raise HTTPException(status_code=500, detail=str(e))
 
@@ -172,25 +186,25 @@ async def get_status():
 async def list_audio_inputs():
     """Return available hardware audio input devices for USB mode."""
     try:
+        # Re-scan devices on Linux, see https://github.com/spatialaudio/python-sounddevice/issues/16
+        if sys.platform == 'linux':
+            log.info("Re-initializing sounddevice to scan for new devices")
+            sd._terminate()
+            sd._initialize()
         devs = sd.query_devices()
         inputs = [
             {"id": idx, "name": d["name"]}
             for idx, d in enumerate(devs)
             if d.get("max_input_channels", 0) > 0 and ("(hw:" in d["name"].lower() or "usb" in d["name"].lower())
         ]
+        log.info('Found %d audio input devices:', len(inputs))
+        for i in inputs:
+            log.info('  %s', i)
         return {"inputs": inputs}
     except Exception as e:
         raise HTTPException(status_code=500, detail=str(e))
 
 
-PTIME = 160 # TODO: seems to have no effect at all
-pcs: Set[RTCPeerConnection] = set()      # keep refs so they don’t GC early
-
-class Offer(BaseModel):
-    sdp: str
-    type: str
-
-
 @app.post("/offer")
 async def offer(offer: Offer):
     log.info("/offer endpoint called")
@@ -210,7 +224,9 @@ async def offer(offer: Offer):
     # create directory for records - only for testing
     os.makedirs("./records", exist_ok=True)
 
-    await multicaster.start_streaming()
+    # Do NOT start the streamer yet – we'll start it lazily once we actually
+    # receive the first audio frame, ensuring WebRTCAudioInput is ready and
+    # avoiding race-conditions on restarts.
     @pc.on("track")
     async def on_track(track: MediaStreamTrack):
         log.info(f"{id_}: track {track.kind} received")
@@ -224,6 +240,12 @@ async def offer(offer: Offer):
                     log.info(
                         f"{id_}: frame sample_rate={frame.sample_rate}, samples_per_channel={frame.samples}, planes={frame.planes}"
                     )
+                    # Lazily start the streamer now that we know a track exists.
+                    if multicaster.streamer is None:
+                        await multicaster.start_streaming()
+                        # Yield control so the Streamer coroutine has a chance to
+                        # create the WebRTCAudioInput before we push samples.
+                        await asyncio.sleep(0)
                     first = False
                     # in stereo case this is interleaved data format
                     frame_array = frame.to_ndarray()
@@ -243,7 +265,6 @@ async def offer(offer: Offer):
                     log.info(f"mono_array.shape: {mono_array.shape}")
 
 
-                    
                 frame_array = frame.to_ndarray()
 
                 # Flatten in case it's (1, N) or (N,)