Properly expose batch_size from OpenVINO similarly to TensorRT (ult…

…ralytics#8514)

Properly expose `batch_size` from OpenVINO

Co-authored-by: Glenn Jocher <glenn.jocher@ultralytics.com>

models/common.py

@@ -361,11 +361,16 @@ def __init__(self, weights='yolov5s.pt', device=torch.device('cpu'), dnn=False,
         elif xml:  # OpenVINO
             LOGGER.info(f'Loading {w} for OpenVINO inference...')
             check_requirements(('openvino',))  # requires openvino-dev: https://pypi.org/project/openvino-dev/
-            from openvino.runtime import Core
+            from openvino.runtime import Core, Layout, get_batch
             ie = Core()
             if not Path(w).is_file():  # if not *.xml
                 w = next(Path(w).glob('*.xml'))  # get *.xml file from *_openvino_model dir
             network = ie.read_model(model=w, weights=Path(w).with_suffix('.bin'))
+            if network.get_parameters()[0].get_layout().empty:
+                network.get_parameters()[0].set_layout(Layout("NCHW"))
+            batch_dim = get_batch(network)
+            if batch_dim.is_static:
+                batch_size = batch_dim.get_length()
             executable_network = ie.compile_model(network, device_name="CPU")  # device_name="MYRIAD" for Intel NCS2
             output_layer = next(iter(executable_network.outputs))
             meta = Path(w).with_suffix('.yaml')