add user_data to AudioFrame (#456)

Author: longcw

livekit-rtc/livekit/rtc/audio_frame.py

@@ -64,6 +64,7 @@ def __init__(
         self._sample_rate = sample_rate
         self._num_channels = num_channels
         self._samples_per_channel = samples_per_channel
+        self._userdata: dict[str, Any] = {}
 
     @staticmethod
     def create(sample_rate: int, num_channels: int, samples_per_channel: int) -> "AudioFrame":
@@ -100,6 +101,13 @@ def _proto_info(self) -> proto_audio.AudioFrameBufferInfo:
         audio_info.samples_per_channel = self.samples_per_channel
         return audio_info
 
+    @property
+    def userdata(self) -> dict[str, Any]:
+        """
+        Returns the user data associated with the audio frame.
+        """
+        return self._userdata
+
     @property
     def data(self) -> memoryview:
         """