Support for retry when 503 error to TTS API.

CHANGELOG.md

@@ -7,6 +7,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [0.0.94] - 2025-11-10
 
+### Changed
+
+- Added support for retrying `SpeechmaticsTTSService` when it returns a 503
+  error. Default values in `InputParams`.
+
 ### Deprecated
 
 - The `KrispFilter` is deprecated and will be removed in a future version. Use

src/pipecat/services/speechmatics/tts.py

@@ -6,6 +6,7 @@
 
 """Speechmatics TTS service integration."""
 
+import asyncio
 from typing import AsyncGenerator, Optional
 from urllib.parse import urlencode
 
@@ -45,7 +46,8 @@ class SpeechmaticsTTSService(TTSService):
     class InputParams(BaseModel):
         """Optional input parameters for Speechmatics TTS configuration."""
 
-        pass
+        retry_interval_s: float = 0.02
+        retry_timeout_s: float = 1.0
 
     def __init__(
         self,
@@ -125,9 +127,29 @@ class SpeechmaticsTTSService(TTSService):
         try:
             await self.start_ttfb_metrics()
 
+            # Retry loop for 503 responses
+            start_time = asyncio.get_event_loop().time()
+
+            while True:
                 async with self._session.post(url, json=payload, headers=headers) as response:
+                    if response.status == 503:
+                        elapsed_time = asyncio.get_event_loop().time() - start_time
+                        if elapsed_time >= self._params.retry_timeout_s:
+                            error_message = (
+                                f"{self} HTTP 503 (timeout after {self._params.retry_timeout_s}s)"
+                            )
+                            logger.error(error_message)
+                            yield ErrorFrame(error=error_message)
+                            return
+
+                        logger.debug(
+                            f"{self} Received 503, retrying in {self._params.retry_interval_s}s..."
+                        )
+                        await asyncio.sleep(self._params.retry_interval_s)
+                        continue
+
                     if response.status != 200:
-                    error_message = f"Speechmatics TTS error: HTTP {response.status}"
+                        error_message = f"{self} HTTP {response.status}"
                         logger.error(error_message)
                         yield ErrorFrame(error=error_message)
                         return
@@ -155,7 +177,9 @@ class SpeechmaticsTTSService(TTSService):
                             complete_bytes = complete_samples * 2
 
                             audio_data = buffer[:complete_bytes]
-                        buffer = buffer[complete_bytes:]  # Keep remaining bytes for next iteration
+                            buffer = buffer[
+                                complete_bytes:
+                            ]  # Keep remaining bytes for next iteration
 
                             yield TTSAudioRawFrame(
                                 audio=audio_data,
@@ -163,8 +187,11 @@ class SpeechmaticsTTSService(TTSService):
                                 num_channels=1,
                             )
 
+                    # Successfully processed the response, break out of retry loop
+                    break
+
         except Exception as e:
-            logger.exception(f"Error generating TTS: {e}")
+            logger.exception(f"{self}: Error generating TTS: {e}")
             yield ErrorFrame(error=f"Speechmatics TTS error: {str(e)}")
         finally:
             yield TTSStoppedFrame()