Is it possible to set batch size other than one with yolo models?

yep it does not accept batches. ;(
(same problem as in the “low level” sample )

unfortunately, it’s not as simple as calling blobFromImages() alone,
the whole post-processing (result parsing, NMS) has to be multiplied

one thing you might want to try is profile your batch code there against multiple forward() calls with a single images (testing all backends/targets you have)