Fix lazy audio path resolution for GPU streaming

Audio playback path was being resolved during parsing when database
may not be ready, causing fallback to non-existent path. Now resolves
lazily when stream starts, matching how audio analyzer works.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

streaming/gpu_output.py

@@ -235,6 +235,7 @@ class GPUHLSOutput:
         self.ipfs_gateway = ipfs_gateway.rstrip("/")
         self._on_playlist_update = on_playlist_update
         self._is_open = True
+        self.audio_source = audio_source
 
         # GPU encoder
         self._gpu_encoder = GPUEncoder(size[0], size[1], fps, crf)
@@ -266,14 +267,29 @@ class GPUHLSOutput:
         print(f"[GPUHLSOutput] Initialized {size[0]}x{size[1]} @ {fps}fps, GPU encoding", file=sys.stderr)
 
     def _setup_muxer(self):
-        """Setup ffmpeg for muxing H.264 to MPEG-TS segments."""
+        """Setup ffmpeg for muxing H.264 to MPEG-TS segments with optional audio."""
         self.local_playlist_path = self.output_dir / "stream.m3u8"
 
         cmd = [
             "ffmpeg", "-y",
             "-f", "h264",  # Input is raw H.264
             "-i", "-",
-            "-c:v", "copy",  # Just copy, no re-encoding
+        ]
+
+        # Add audio input if provided
+        if self.audio_source:
+            cmd.extend(["-i", str(self.audio_source)])
+            cmd.extend(["-map", "0:v", "-map", "1:a"])
+
+        cmd.extend([
+            "-c:v", "copy",  # Just copy video, no re-encoding
+        ])
+
+        # Add audio codec if we have audio
+        if self.audio_source:
+            cmd.extend(["-c:a", "aac", "-b:a", "128k", "-shortest"])
+
+        cmd.extend([
             "-f", "hls",
             "-hls_time", str(self.segment_duration),
             "-hls_list_size", "0",
@@ -281,12 +297,14 @@ class GPUHLSOutput:
             "-hls_segment_type", "mpegts",
             "-hls_segment_filename", str(self.output_dir / "segment_%05d.ts"),
             str(self.local_playlist_path),
-        ]
+        ])
+
+        print(f"[GPUHLSOutput] FFmpeg cmd: {' '.join(cmd)}", file=sys.stderr)
 
         self._muxer = subprocess.Popen(
             cmd,
             stdin=subprocess.PIPE,
-            stderr=subprocess.DEVNULL,
+            stderr=subprocess.PIPE,  # Capture stderr for debugging
         )
 
     def write(self, frame: Union[np.ndarray, 'cp.ndarray'], t: float = 0):