FalImageGenService: load image async to not block the event loop

CHANGELOG.md

@@ -105,6 +105,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Fixed
 
+- Fixed a `FalImageGenService` issue that was causing the event loop to be
+  blocked while loading the downloadded image.
+
 - Fixed a `CartesiaTTSService` service issue that would cause audio overlapping
   in some cases.
 

src/pipecat/services/fal.py

@@ -4,6 +4,7 @@
 # SPDX-License-Identifier: BSD 2-Clause License
 #
 
+import asyncio
 import io
 import os
 from typing import AsyncGenerator, Dict, Optional, Union
@@ -53,6 +54,11 @@ class FalImageGenService(ImageGenService):
             os.environ["FAL_KEY"] = key
 
     async def run_image_gen(self, prompt: str) -> AsyncGenerator[Frame, None]:
+        def load_image_bytes(encoded_image: bytes):
+            buffer = io.BytesIO(encoded_image)
+            image = Image.open(buffer)
+            return (image.tobytes(), image.size, image.format)
+
         logger.debug(f"Generating image from prompt: {prompt}")
 
         response = await fal_client.run_async(
@@ -73,10 +79,8 @@ class FalImageGenService(ImageGenService):
         logger.debug(f"Downloading image {image_url} ...")
         async with self._aiohttp_session.get(image_url) as response:
             logger.debug(f"Downloaded image {image_url}")
-            image_stream = io.BytesIO(await response.content.read())
-            image = Image.open(image_stream)
+            encoded_image = await response.content.read()
+            (image_bytes, size, format) = await asyncio.to_thread(load_image_bytes, encoded_image)
 
-            frame = URLImageRawFrame(
-                url=image_url, image=image.tobytes(), size=image.size, format=image.format
-            )
+            frame = URLImageRawFrame(url=image_url, image=image_bytes, size=size, format=format)
             yield frame