feat: expose media_io_kwargs at runtime (#34778)

Signed-off-by: Alexandre Milesi <milesial@users.noreply.github.com>

vllm/entrypoints/openai/chat_completion/protocol.py

@@ -268,6 +268,13 @@ class ChatCompletionRequest(OpenAIBaseModel):
             "Will be accessible by the chat template."
         ),
     )
+    media_io_kwargs: dict[str, dict[str, Any]] | None = Field(
+        default=None,
+        description=(
+            "Additional kwargs to pass to the media IO connectors, "
+            "keyed by modality. Merged with engine-level media_io_kwargs."
+        ),
+    )
     mm_processor_kwargs: dict[str, Any] | None = Field(
         default=None,
         description=("Additional kwargs to pass to the HF processor."),
@@ -366,6 +373,7 @@ class ChatCompletionRequest(OpenAIBaseModel):
                     reasoning_effort=self.reasoning_effort,
                 ),
             ),
+            media_io_kwargs=self.media_io_kwargs,
         )
 
     def build_tok_params(self, model_config: ModelConfig) -> TokenizeParams: