fix(node): verify D455 access and share sensor progress and recording UI

apps/node-agent/sensors/media.py

@@ -5,6 +5,7 @@ import ipaddress
 import json
 import time
 import uuid
+from fractions import Fraction
 
 import aioice.ice
 from aiortc import RTCConfiguration, RTCPeerConnection, RTCSessionDescription, VideoStreamTrack
@@ -35,11 +36,16 @@ class CameraTrack(VideoStreamTrack):
     def __init__(self, device, layer):
         super().__init__()
         self.device, self.layer = device, layer
+        self.started = None
+        self.sequence = 0
 
     async def recv(self):
-        pts, base = await self.next_timestamp()
-        # Bound preview to 15 Hz; hardware profiles and raw recording are independent.
-        await asyncio.sleep(1 / 30)
+        # Fixed 15 Hz preview clock; raw hardware timing is independent.
+        if self.started is None:
+            self.started = time.monotonic()
+        await asyncio.sleep(max(0, self.started + self.sequence / 15 - time.monotonic()))
+        pts, base = self.sequence * 6000, Fraction(1, 90000)
+        self.sequence += 1
         while self.layer not in self.device.images:
             await asyncio.sleep(0.1)
         frame = VideoFrame.from_ndarray(self.device.images[self.layer], format="rgb24")