How to know frame size in deepstream?

Please provide complete information as applicable to your setup.

• Hardware Platform (Jetson / GPU)
Xavier
• DeepStream Version
5.1
• JetPack Version (valid for Jetson only)

R32 (release), REVISION: 4.3, GCID: 21589087, BOARD: t186ref, EABI: aarch64, DATE: Fri Jun 26 04:34:27 UTC 2020

• TensorRT Version
latest
• NVIDIA GPU Driver Version (valid for GPU only)
10.2
• Issue Type( questions, new requirements, bugs)
question
• How to reproduce the issue ? (This is for bugs. Including which sample app is using, the configuration files content, the command line used and other details for reproducing)
• Requirement details( This is for new requirement. Including the module name-for which plugin or for which sample application, the function description)
How do I know frame size in deepstream-app?
I can have from probe and batch_meta data.
I like to have the info before app start iterations.

NvDsFrameMeta → source_frame_width/source_frame_height