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Prequisites:
- DeepStreamSDK 6.2
- Python 3.8
- Gst-python

To run the test app:
  $ python3 deepstream_custom_binding_test.py <h264_elementary_stream>

This document shall describe the sample deepstream-custom-binding-test application.

It is meant for simple demonstration of how to use NvDsUserMeta to attach custom
data structure to the buffer at upstream element's pad using probe function and extract
the same custom data structure later at a downstream element's pad, also using another
probe function.

The elements used in the pipeline are as follows:
FileSrc -> H264Parse -> NvV4l2Decoder -> NvStreammux -> Queue -> Queue -> FakeSink

First probe function attaches custom structure, which is added to the PyDS bindings, to the NvDsUserMeta, which is added to the frame by PyDS using pyds.nvds_add_user_meta_to_frame()
This first probe is added at the srcpad of NvStreamMux.

For copying integers and strings from python data structure to PyDS bindings,
the function pyds.copy_custom_struct() is used.

Second probe function reads the values attached as part of this custom structure after
the buffer reaches sinkpad of FakeSink. The allocated memory is then freed using pyds.release_custom_struct()