fix(python-backend): Fix Nova Sonic protocol and SDK v0.1.0 compatibi…

samples/speech-to-speech/backend/python_app/clients/bedrock_client.py

@@ -15,7 +15,6 @@
 import logging
 import warnings
 import os
-import time
 from aws_sdk_bedrock_runtime.client import (
  BedrockRuntimeClient,
  InvokeModelWithBidirectionalStreamOperationInput,
@@ -24,15 +23,10 @@
  InvokeModelWithBidirectionalStreamInputChunk,
  BidirectionalInputPayloadPart,
 )
-from aws_sdk_bedrock_runtime.config import (
- Config,
- HTTPAuthSchemeResolver,
- SigV4AuthScheme,
-)
-from smithy_aws_core.credentials_resolvers.environment import (
- EnvironmentCredentialsResolver,
-)
-from smithy_aws_core.credentials_resolvers.container import ContainerCredentialsResolver
+from aws_sdk_bedrock_runtime.config import Config
+from smithy_aws_core.auth.sigv4 import SigV4AuthScheme
+from smithy_aws_core.identity.environment import EnvironmentCredentialsResolver
+from smithy_aws_core.identity.container import ContainerCredentialsResolver
 from smithy_http.aio.aiohttp import AIOHTTPClient, AIOHTTPClientConfig
 
 # Configure logging
@@ -100,8 +94,7 @@ def initialize_client(self):
  endpoint_uri=f"https://bedrock-runtime.{self.region}.amazonaws.com",
  region=self.region,
  aws_credentials_identity_resolver=resolver,
- http_auth_scheme_resolver=HTTPAuthSchemeResolver(),
- http_auth_schemes={"aws.auth#sigv4": SigV4AuthScheme()},
+ auth_schemes={"aws.auth#sigv4": SigV4AuthScheme(service="bedrock")},
  )
  self.bedrock_client = BedrockRuntimeClient(config=config)
  logger.info(

samples/speech-to-speech/backend/python_app/core/audio_processor.py

@@ -83,6 +83,40 @@ async def queue_audio(self, prompt_name: str, content_name: str, audio_base64: s
  )
  return
 
+ # Add audio validation to detect silence
+ try:
+ import base64
+ audio_bytes = base64.b64decode(audio_base64)
+
+ # Check if audio is silence (all zeros or very low values)
+ if len(audio_bytes) > 0:
+ # Convert bytes to 16-bit signed integers for analysis
+ import struct
+ num_samples = len(audio_bytes) // 2 # 16-bit samples
+
+ if num_samples > 0:
+ # Unpack first few samples to check for silence
+ sample_check_count = min(100, num_samples)
+ samples = struct.unpack(f'{sample_check_count}h', audio_bytes[:sample_check_count * 2])
+
+ # Calculate max absolute value
+ max_val = max(abs(s) for s in samples)
+
+ # Threshold for silence detection (16-bit audio range is -32768 to 32767)
+ # Only warn on truly silent audio (complete zeros)
+ if max_val == 0:
+ self.logger.warning(
+ "Detected completely silent audio chunk (all zeros). "
+ "Frontend may not be sending real microphone audio."
+ )
+ elif max_val < 50:
+ # Very low audio - only log at debug level
+ self.logger.debug(f"Very low audio level - max amplitude: {max_val}")
+ # Normal audio - no logging needed (reduces verbosity)
+
+ except Exception as e:
+ self.logger.error(f"Error validating audio: {e}")
+
  # Use put_nowait() like original code to avoid blocking/timing delays
  self.audio_input_queue.put_nowait(
  {

samples/speech-to-speech/backend/python_app/core/websocket_handler.py

@@ -123,12 +123,12 @@ async def handle_connection(self, websocket):
  # Start audio processor
  await self.audio_processor.start(self.bedrock_client, self.stream)
 
- # Start response processing task
- self.response_task = asyncio.create_task(self._process_responses(websocket))
-
  # Register message handlers
  self._register_message_handlers()
 
+ # Start response processing task AFTER setup is complete 
+ self.response_task = asyncio.create_task(self._process_responses(websocket))
+
  # Main message processing loop
  async for message in websocket:
  await self._handle_message(websocket, message)
@@ -235,14 +235,42 @@ async def _handle_message(self, websocket, message):
  list(data.get("event", {}).keys())[0] if "event" in data else None
  )
 
- # Store session information
- if event_type == "promptStart":
- self.prompt_name = data["event"]["promptStart"]["promptName"]
- elif (
- event_type == "contentStart"
- and data["event"]["contentStart"].get("type") == "AUDIO"
- ):
- self.audio_content_name = data["event"]["contentStart"]["contentName"]
+ # Event sequence tracking (reduced verbosity)
+ if event_type:
+ if event_type == "sessionStart":
+ self.logger.info("Session started")
+ elif event_type == "promptStart":
+ self.prompt_name = data["event"]["promptStart"]["promptName"]
+ self.logger.debug("Prompt started")
+ elif event_type == "contentStart":
+ content_type = data["event"]["contentStart"].get("type")
+ role = data["event"]["contentStart"].get("role", "UNSPECIFIED")
+ content_name = data["event"]["contentStart"].get("contentName")
+
+ # Only log at debug level for routine content
+ self.logger.debug(f"Content start: type={content_type}, role={role}")
+
+ # Validate first content block has SYSTEM role
+ if not hasattr(self, '_first_content_received'):
+ self._first_content_received = True
+ if role != "SYSTEM":
+ self.logger.error(f"First content block must have SYSTEM role, received {role}")
+ await websocket.send(json.dumps({
+ "type": "error",
+ "message": f"First content block must have SYSTEM role, received {role}"
+ }))
+
+ # Store audio content name
+ if content_type == "AUDIO":
+ self.audio_content_name = content_name
+ if role != "USER":
+ self.logger.warning(f"Audio content should have USER role, received {role}")
+
+ elif event_type == "sessionEnd":
+ self.logger.info("Session ended")
+ # Other events logged at debug level only
+ elif event_type in ["textInput", "contentEnd", "promptEnd"]:
+ self.logger.debug(f"Event: {event_type}")
 
  # Send event to Bedrock
  await self.bedrock_client.send_event(self.stream, data)

samples/speech-to-speech/backend/python_app/events/s2s_events.py

@@ -157,6 +157,7 @@ def content_start_audio(
  "promptName": prompt_name,
  "contentName": content_name,
  "type": "AUDIO",
+ "role": "USER", # Required by Nova Sonic API
  "interactive": True,
  "audioInputConfiguration": audio_input_config,
  }

samples/speech-to-speech/backend/python_app/requirements.txt

@@ -1,6 +1,6 @@
 # Core dependencies
-aws_sdk_bedrock_runtime==0.0.2
-smithy-aws-core==0.0.3
+aws_sdk_bedrock_runtime==0.1.0
+smithy-aws-core==0.1.0
 python-dotenv>=1.1.0
 aiohttp>=3.8.0