[Frontend] Support configurable mm placeholder strings & flexible video sampling policies via CLI flags. (#20105)

Signed-off-by: Chenheli Hua <huachenheli@outlook.com>

vllm/multimodal/audio.py

@@ -83,6 +83,16 @@ class AudioResampler:
 
 class AudioMediaIO(MediaIO[tuple[npt.NDArray, float]]):
 
+    def __init__(self, **kwargs) -> None:
+        super().__init__()
+
+        # `kwargs` contains custom arguments from
+        # --media-io-kwargs for this modality.
+        # They can be passed to the underlying
+        # media loaders (e.g. custom implementations)
+        # for flexible control.
+        self.kwargs = kwargs
+
     def load_bytes(self, data: bytes) -> tuple[npt.NDArray, float]:
         return librosa.load(BytesIO(data), sr=None)