[Frontend] Enable decord to load video from base64 (#11492)

Signed-off-by: DarkLight1337 <tlleungac@connect.ust.hk>

vllm/multimodal/utils.py

@@ -125,17 +125,7 @@ async def async_fetch_image(image_url: str,
     return image.convert(image_mode)
 
 
-def _load_video_frames_from_bytes(b: bytes):
-    frame = Image.open(BytesIO(b))
-    return np.array(frame)
-
-
-def load_video_frames_from_base64(frame: Union[bytes, str]):
-    """Load frame from base64 format."""
-    return _load_video_frames_from_bytes(base64.b64decode(frame))
-
-
-def _load_video_from_bytes(b: bytes, num_frames: int = 32):
+def _load_video_from_bytes(b: bytes, num_frames: int = 32) -> npt.NDArray:
     _, decord = try_import_video_packages()
 
     video_path = BytesIO(b)
@@ -155,14 +145,18 @@ def _load_video_from_bytes(b: bytes, num_frames: int = 32):
     return frames
 
 
-def _load_video_from_data_url(video_url: str):
-    # Only split once and assume the second part is the base64 encoded image
-    frames_base64 = video_url.split(",")[1:]
+def _load_video_from_data_url(video_url: str) -> npt.NDArray:
+    # Only split once and assume the second part is the base64 encoded video
+    _, video_base64 = video_url.split(",", 1)
+
+    if video_url.startswith("data:video/jpeg;"):
         return np.stack([
-        load_video_frames_from_base64(frame_base64)
-        for frame_base64 in frames_base64
+            np.array(load_image_from_base64(frame_base64))
+            for frame_base64 in video_base64.split(",")
         ])
 
+    return load_video_from_base64(video_base64)
+
 
 def fetch_video(video_url: str, *, num_frames: int = 32) -> npt.NDArray:
     """
@@ -342,7 +336,7 @@ def rescale_image_size(image: Image.Image,
     return image
 
 
-def try_import_video_packages() -> Any:
+def try_import_video_packages():
     try:
         import cv2
         import decord
@@ -384,7 +378,7 @@ def sample_frames_from_video(frames: npt.NDArray,
         return sampled_frames
 
 
-def encode_video_base64(frames: npt.NDArray):
+def encode_video_base64(frames: npt.NDArray) -> str:
     base64_frames = []
     frames_list = [frames[i] for i in range(frames.shape[0])]
     for frame in frames_list:
@@ -393,6 +387,11 @@ def encode_video_base64(frames: npt.NDArray):
     return ",".join(base64_frames)
 
 
+def load_video_from_base64(video: Union[bytes, str]) -> npt.NDArray:
+    """Load video from base64 format."""
+    return _load_video_from_bytes(base64.b64decode(video))
+
+
 def resolve_visual_encoder_outputs(
     encoder_outputs: Union[torch.Tensor, list[torch.Tensor]],
     feature_sample_layers: Optional[list[int]],