feat: preserve volume when overriding speed in Prosody configuration

Signed-off-by: James Ding <jamesding365@gmail.com>

Author: twangodev

src/fishaudio/resources/tts.py

@@ -147,7 +147,7 @@ def convert(
             request.latency = latency
 
         if speed is not None:
-            request.prosody = Prosody(speed=speed)
+            request.prosody = Prosody.from_speed_override(speed, base=config.prosody)
 
         payload = request.model_dump(exclude_none=True)
 
@@ -263,7 +263,9 @@ def text_generator():
             tts_request.latency = latency
 
         if speed is not None:
-            tts_request.prosody = Prosody(speed=speed)
+            tts_request.prosody = Prosody.from_speed_override(
+                speed, base=config.prosody
+            )
 
         executor = ThreadPoolExecutor(max_workers=max_workers)
 
@@ -394,7 +396,7 @@ async def convert(
             request.latency = latency
 
         if speed is not None:
-            request.prosody = Prosody(speed=speed)
+            request.prosody = Prosody.from_speed_override(speed, base=config.prosody)
 
         payload = request.model_dump(exclude_none=True)
 
@@ -508,7 +510,9 @@ async def text_generator():
             tts_request.latency = latency
 
         if speed is not None:
-            tts_request.prosody = Prosody(speed=speed)
+            tts_request.prosody = Prosody.from_speed_override(
+                speed, base=config.prosody
+            )
 
         ws: AsyncWebSocketSession
         async with aconnect_ws(

src/fishaudio/types/tts.py

@@ -20,6 +20,24 @@ class Prosody(BaseModel):
     speed: float = 1.0
     volume: float = 0.0
 
+    @classmethod
+    def from_speed_override(
+        cls, speed: float, base: Optional["Prosody"] = None
+    ) -> "Prosody":
+        """
+        Create Prosody with speed override, preserving volume from base.
+
+        Args:
+            speed: Speed value to use
+            base: Base prosody to preserve volume from (if any)
+
+        Returns:
+            New Prosody instance with overridden speed
+        """
+        if base:
+            return cls(speed=speed, volume=base.volume)
+        return cls(speed=speed)
+
 
 class TTSConfig(BaseModel):
     """

tests/unit/test_tts.py

@@ -359,19 +359,19 @@ def test_convert_parameter_format_overrides_config(
     def test_convert_parameter_speed_overrides_config_prosody(
         self, tts_client, mock_client_wrapper
     ):
-        """Test that parameter speed overrides config.prosody."""
+        """Test that parameter speed overrides config.prosody speed but preserves volume."""
         mock_response = Mock()
         mock_response.iter_bytes.return_value = iter([b"audio"])
         mock_client_wrapper.request.return_value = mock_response
 
         config = TTSConfig(prosody=Prosody(speed=2.0, volume=0.5))
         list(tts_client.convert(text="Hello", speed=1.5, config=config))
 
-        # Verify parameter speed takes precedence
+        # Verify parameter speed takes precedence but volume is preserved
         call_args = mock_client_wrapper.request.call_args
         payload = ormsgpack.unpackb(call_args[1]["content"])
         assert payload["prosody"]["speed"] == 1.5
-        # Note: volume from config.prosody is lost when speed parameter is used
+        assert payload["prosody"]["volume"] == 0.5  # Preserved from config!
 
     def test_convert_combined_convenience_parameters(
         self, tts_client, mock_client_wrapper
@@ -721,7 +721,7 @@ async def async_iter_bytes():
     async def test_convert_parameter_speed_overrides_config_prosody(
         self, async_tts_client, async_mock_client_wrapper
     ):
-        """Test that parameter speed overrides config.prosody (async)."""
+        """Test that parameter speed overrides config.prosody speed but preserves volume (async)."""
         mock_response = Mock()
 
         async def async_iter_bytes():
@@ -737,11 +737,11 @@ async def async_iter_bytes():
         ):
             audio_chunks.append(chunk)
 
-        # Verify parameter speed takes precedence
+        # Verify parameter speed takes precedence but volume is preserved
         call_args = async_mock_client_wrapper.request.call_args
         payload = ormsgpack.unpackb(call_args[1]["content"])
         assert payload["prosody"]["speed"] == 1.5
-        # Note: volume from config.prosody is lost when speed parameter is used
+        assert payload["prosody"]["volume"] == 0.5  # Preserved from config!
 
     @pytest.mark.asyncio
     async def test_convert_combined_convenience_parameters(