Exported model batch size validation fix (ultralytics#14845)

Co-authored-by: Glenn Jocher <[email protected]>

ultralytics/engine/validator.py

@@ -136,8 +136,8 @@ def __call__(self, trainer=None, model=None):
             if engine:
                 self.args.batch = model.batch_size
             elif not pt and not jit:
-                self.args.batch = 1  # export.py models default to batch-size 1
-                LOGGER.info(f"Forcing batch=1 square inference (1,3,{imgsz},{imgsz}) for non-PyTorch models")
+                self.args.batch = model.metadata.get("batch", 1)  # export.py models default to batch-size 1
+                LOGGER.info(f"Setting batch={self.args.batch} input of shape ({self.args.batch}, 3, {imgsz}, {imgsz})")
 
             if str(self.args.data).split(".")[-1] in {"yaml", "yml"}:
                 self.data = check_det_dataset(self.args.data)