Trying to send custom data through redis pub/sub

Accelerated Computing Intelligent Video Analytics DeepStream SDK
1

My setup:

• Hardware Platform: Jetson AGX Orin Developer Kit 64 GB
• DeepStream Version: : 7.1
• JetPack Version: 6.2
• TensorRT Version: Not sure
• NVIDIA GPU Driver Version (valid for GPU only): Not sure
Hello,

As a heads up, I am pretty new to DeepStream, and I am using the DeepStream Python bindings to generate the NVIDIA DeepStream pipeline.

I have created a pipeline that runs on the GPU and takes pictures from my camera to infer them using a YOLOv7 model. What I want to do now is use nvmsgconv and nvmsgbroker to publish messages to Redis using the Redis DeepStream plugin. Specifically, I would like to publish a custom payload, such as a JSON object that contains some information from the inference, as well as the image that was sent to the inference server.

I found this in the DeepStream documentation:

This plugin can be used to implement a custom schema:

  • By implementing the nvds_msg2p interface: If a library that implements the custom schema needs to be integrated with the DeepStream SDK, wrap the library in the nvds_msg2p interface and set the plugin’s msg2p-libproperty to the library’s name. Set the payload-type property to PAYLOAD_CUSTOM.

I am not sure how to proceed, but I believe I need to implement nvds_msg2p in C++. My question is: once I have implemented that interface, how can I call the implementation from the Python code? I have checked the documentation, but I haven’t found an example of this.

Thank you in advance for your help!

3

Hi,

To use a custom payload with nvmsgconv and nvmsgbroker from Python, implement your custom nvds_msg2p interface in C++ as a shared library, then set it via:

msgconv.set_property("msg2p-lib", "/path/to/libnvds_msgconv_custom.so")
msgconv.set_property("payload-type", 0)  # PAYLOAD_CUSTOM

From Python, attach data to each frame using nvds_add_user_meta_to_frame() with a NvDsEventMsgMeta object. This metadata will be passed to your C++ payload.

4

Hello, thanks for your reply.

Yes, I have already implemented my custom nvds_msg2p interface. The thing is that NvDsEventMsgMeta already has its structure defined. If I want to add a new type of object to NvDsEventMsgMeta, I would need to define it and compile it with the rest of the DeepStream code, correct?

For example, if I want to add the following JSON:

{
  "parameter1": "some string",
  "parameter2": "some string"
}

I would need to create a type in C++ called CustomPayload and add it as a new attribute to NvDsEventMsgMeta, then compile everything again, right?

Moreover, I would have to allocate memory for this new object. This means I would also need to modify the Python bindings to create a function like pyds.alloc_nvds_person_object() and recompile the bindings. Is this the process you would recommend, or is there an easier way?
I’ve checked also your replies in other threads such as this one and I wonder if the information there could be applicable in this case. What do you think?
Thank you!

5

if you want to send image, please find “3.Send the image by the broker based on Kafka” in the readme of /opt/nvidia/deepstream/deepstream/sources/apps/sample_apps/deepstream-test4/.

6

Thanks for your message, I checked the file that you mentioned. It says I have to set payload-type and msg2p-newapi to 1. But then I wouldnt be able to send a custom json, or am I missing something?
If I want to send a JSON such as

{
  "parameter1": "some string",
  "parameter2": "some string"
}

shouldnt the payload-type be 257?

Also, I thought it would be easier to send custom data through the otherAtts property from the NvDsEventMsgMeta. If I would use the newapi I wouldn’t be able to use this property and would have to create a custom object?

7

deepstream-test4 is a ready-made sample to send jpg. How to write it in Python is mentioned in the readme.. Yes, If you want to send images, please set the “payload-type: 1” and “msg2p-newapi: 1”.
if you want to use otherAtts, please refer to this topic.

8

There is no update from you for a period, assuming this is not an issue anymore. Hence we are closing this topic. If need further support, please open a new one. Thanks

9

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