services(cartesia): fix TTFB

src/pipecat/services/cartesia.py

@@ -82,7 +82,6 @@ class CartesiaTTSService(TTSService):
         self._timestamped_words_buffer = []
         self._receive_task = None
         self._context_appending_task = None
-        self._waiting_for_ttfb = False
 
     def can_generate_metrics(self) -> bool:
         return True
@@ -127,7 +126,6 @@ class CartesiaTTSService(TTSService):
             self._context_id = None
             self._context_id_start_timestamp = None
             self._timestamped_words_buffer = []
-            self._waiting_for_ttfb = False
             await self.stop_all_metrics()
         except Exception as e:
             logger.exception(f"{self} error closing websocket: {e}")
@@ -148,6 +146,7 @@ class CartesiaTTSService(TTSService):
                 if not msg or msg["context_id"] != self._context_id:
                     continue
                 if msg["type"] == "done":
+                    await self.stop_ttfb_metrics()
                     # unset _context_id but not the _context_id_start_timestamp because we are likely still
                     # playing out audio and need the timestamp to set send context frames
                     self._context_id = None
@@ -158,11 +157,9 @@ class CartesiaTTSService(TTSService):
                         list(zip(msg["word_timestamps"]["words"], msg["word_timestamps"]["end"]))
                     )
                 elif msg["type"] == "chunk":
+                    await self.stop_ttfb_metrics()
                     if not self._context_id_start_timestamp:
                         self._context_id_start_timestamp = time.time()
-                    if self._waiting_for_ttfb:
-                        await self.stop_ttfb_metrics()
-                        self._waiting_for_ttfb = False
                     frame = AudioRawFrame(
                         audio=base64.b64decode(msg["data"]),
                         sample_rate=self._output_format["sample_rate"],
@@ -198,11 +195,8 @@ class CartesiaTTSService(TTSService):
             if not self._websocket:
                 await self._connect()
 
-            if not self._waiting_for_ttfb:
-                await self.start_ttfb_metrics()
-                self._waiting_for_ttfb = True
-
             if not self._context_id:
+                await self.start_ttfb_metrics()
                 self._context_id = str(uuid.uuid4())
 
             msg = {