Close Stream from Backend (#222)

* Close from backend

* Add code

backend/fastrtc/utils.py

@@ -32,6 +32,11 @@ class AdditionalOutputs:
         self.args = args
 
 
+class CloseStream:
+    def __init__(self, msg: str = "Stream closed") -> None:
+        self.msg = msg
+
+
 class DataChannel(Protocol):
     def send(self, message: str) -> None: ...
 
@@ -39,6 +44,7 @@ class DataChannel(Protocol):
 def create_message(
     type: Literal[
         "send_input",
+        "end_stream",
         "fetch_output",
         "stopword",
         "error",
@@ -98,9 +104,13 @@ class WebRTCError(Exception):
         _send_log(message, "error")
 
 
-def split_output(data: tuple | Any) -> tuple[Any, AdditionalOutputs | None]:
+def split_output(
+    data: tuple | Any,
+) -> tuple[Any, AdditionalOutputs | CloseStream | None]:
     if isinstance(data, AdditionalOutputs):
         return None, data
+    if isinstance(data, CloseStream):
+        return None, data
     if isinstance(data, tuple):
         # handle the bare audio case
         if 2 <= len(data) <= 3 and isinstance(data[1], np.ndarray):
@@ -109,11 +119,11 @@ def split_output(data: tuple | Any) -> tuple[Any, AdditionalOutputs | None]:
             raise ValueError(
                 "The tuple must have exactly two elements: the data and an instance of AdditionalOutputs."
             )
-        if not isinstance(data[-1], AdditionalOutputs):
+        if not isinstance(data[-1], (AdditionalOutputs, CloseStream)):
             raise ValueError(
                 "The last element of the tuple must be an instance of AdditionalOutputs."
             )
-        return data[0], cast(AdditionalOutputs, data[1])
+        return data[0], cast(AdditionalOutputs | CloseStream, data[1])
     return data, None
 
 
@@ -152,6 +162,8 @@ async def player_worker_decode(
                 cast(DataChannel, channel()).send(create_message("fetch_output", []))
 
             if frame is None:
+                if isinstance(outputs, CloseStream):
+                    await queue.put(outputs)
                 if quit_on_none:
                     await queue.put(None)
                     break
@@ -203,7 +215,8 @@ async def player_worker_decode(
                 processed_frame.time_base = audio_time_base
                 audio_samples += processed_frame.samples
                 await queue.put(processed_frame)
-
+            if isinstance(outputs, CloseStream):
+                await queue.put(outputs)
         except (TimeoutError, asyncio.TimeoutError):
             logger.warning(
                 "Timeout in frame processing cycle after %s seconds - resetting", 60