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• Description
• Prerequisites
• How to run
  • Build and run docker images
  • Run deepstream python script
  • Consume messages
• Details
  • Add analytics msg meta to NvDsEventMsgMeta
  • Remake libnvds_msgconv.so
  • Build and install Python bindings
• References

The deepstream-occupancy-analytics repo provides a method to send analytics data to kafka, but it is C version. It's not easy for python programmers who don't have enough time to figure out how to use it.

By referring to How do I change JSON payload output? and Problem with reading nvdsanalytics output via Kafka, I make some changes of C source code, insert custom lc_curr_straight and lc_cum_straight in NvDsEventMsgMeta and send to kafka. Then build the deepstream python bindings.

In deepstream forums, the maintainer replied that deepstream python will support custom message payload feature in the future release.

the main steps as follows:

1. Add analytics msg meta to NvDsEventMsgMeta
2. modify eventmsg_payload.cpp and remake libnvds_msgconv.so
3. Build and install Python bindings

After that, the only thing to send line-crossing data is to assign analytics data to msg_meta.lc_curr_straight and msg_meta.lc_cum_straight, the key of dict is depend on nvdsanalytics config

# line crossing current count of frame
obj_lc_curr_cnt = user_meta_data.objLCCurrCnt
# line crossing cumulative count
obj_lc_cum_cnt = user_meta_data.objLCCumCnt
msg_meta.lc_curr_straight = obj_lc_curr_cnt["straight"]
msg_meta.lc_cum_straight = obj_lc_cum_cnt["straight"] 

the keys of obj_lc_curr_cnt and obj_lc_cum_cnt are defined in config_nvdsanalytics.txt

Actually, There is a simple way to send custom meesages. If you don't need to process scale of video streams, or the latency is not important, you can use kafka-python library to send messages instead of use nvmsgconv and nvmsgbroker.

If not , you should go back to modeify the C source code and build it. Since the probe is a blocking operation, it is not suitable for complex processing.

• nvidia-docker2
• deepstream-6.1

If you want custom you own messages, you can refer to Details

• clone this repo, in deepstream_python_nvdsanalytics_to_kafka directory, run sh docker/build.sh <image_name> to build a docker image, e.g: sh docker/build.sh deepstream:6.1-triton-jupyter-python-custom

• run the docker image and access jupyter

  docker run --gpus  device=0  -p 8888:8888 -d --shm-size=1g  -w /opt/nvidia/deepstream/deepstream-6.1/sources/deepstream_python_apps/mount/   -v ~/deepstream_python_nvdsanalytics_to_kafka/:/opt/nvidia/deepstream/deepstream-6.1/sources/deepstream_python_apps/mount  deepstream:6.1-triton-jupyter-python-custom

  type http://<host_ip>:8888 on browser to access jupyter

• (optional) on kubernetes master node, run sh /docker/ds-jupyter-statefulset.sh to launch deepstream instance on kubernetes. The premise is that nvidia-device-plugin is installed on your kubernetes

the deepstream python pipeline of /pyds_kafka_example/run.py is base on deepstream-test4 and deepstream-nvdsanalytics the deepstrem python pipeline architecture is as follows:

• before running, set the partion-key = deviceId in pyds_kafka_example/cfg_kafka.txt, it will set partition-key by the deviceId of payload to be sent

• install java
  apt update && apt install -y openjdk-11-jdk

• install kafka: [https://kafka.apache.org/quickstart] and create the kafka topic:

  tar -xzf kafka_2.13-3.2.1.tgz
  cd kafka_2.13-3.2.1
  bin/zookeeper-server-start.sh config/zookeeper.properties
  bin/kafka-server-start.sh config/server.properties
  bin/kafka-topics.sh --create --topic ds-kafka --bootstrap-server localhost:9092

• cd pyds_kafka_example path and run the python script, e.g:

  python3 run.py -i /opt/nvidia/deepstream/deepstream-6.1/samples/streams/sample_720p.h264 -p /opt/nvidia/deepstream/deepstream-6.1/lib/libnvds_kafka_proto.so --conn-str="localhost;9092;ds-kafka" -s 0 --no-display

# go to kafka_2.13-3.2.1 directory and run
bin/kafka-console-consumer.sh --topic ds-kafka --from-beginning --bootstrap-server localhost:9092

The output will look like this:

{
  "messageid" : "34359fe1-fa36-4268-b6fc-a302dbab8be9",
  "@timestamp" : "2022-08-20T09:05:01.695Z",
  "deviceId" : "device_test",
  "analyticsModule" : {
    "id" : "XYZ",
    "description" : "\"Vehicle Detection and License Plate Recognition\"",
    "source" : "OpenALR",
    "version" : "1.0",
    "lc_curr_straight" : 1,
    "lc_cum_straight" : 39
  }
}

In L232 of nvdsmeta_schema.h, insert custom analytics msg meta of typedef struct NvDsEventMsgMeta :

  guint lc_curr_straight;
  guint lc_cum_straight;

• deepstream_schema
  In /opt/nvidia/deepstream/deepstream/sources/libs/nvmsgconv, add same analytics msg meta in nvmsgconv/deestream_schema/deepstream_schema.h at L93 of struct NvDsAnalyticsObject

    guint lc_curr_straight;
    guint lc_cum_straight;

• eventmsg_payload
  The most important step of cutstom your message payload. in nvmsgconv/deepstream_schema/eventmsg_payload.cpp, your can insert your analytics msg meta in the generate_analytics_module_object function at L186:

    // custom analytics data
    // json_object_set_int_member (analyticsObj, <the key of your msg to be send>, <corresponding value>);
    json_object_set_int_member (analyticsObj, "lc_curr_straight", meta->lc_curr_straight);
    json_object_set_int_member (analyticsObj, "lc_cum_straight", meta->lc_cum_straight);

  You can also comment some payload that your don't want to send to kafka. In generate_event_message function at L536:

  // // place object
  // placeObj = generate_place_object (privData, meta);
  
  // // sensor object
  // sensorObj = generate_sensor_object (privData, meta);
  
  // analytics object
  analyticsObj = generate_analytics_module_object (privData, meta);
  
  // // object object
  // objectObj = generate_object_object (privData, meta);
  
  // // event object
  // eventObj = generate_event_object (privData, meta);
  
  // root object
  rootObj = json_object_new ();
  json_object_set_string_member (rootObj, "messageid", msgIdStr);
  // json_object_set_string_member (rootObj, "mdsversion", "1.0");
  json_object_set_string_member (rootObj, "@timestamp", meta->ts);
  
  // use the orginal params sensorStr in NvDsEventMsgMeta to accept deviceId that generated by python script
  json_object_set_string_member (rootObj, "deviceId", meta->sensorStr);
  // json_object_set_object_member (rootObj, "place", placeObj);
  // json_object_set_object_member (rootObj, "sensor", sensorObj);
  json_object_set_object_member (rootObj, "analyticsModule", analyticsObj);
  
  // not use these metadata
  // json_object_set_object_member (rootObj, "object", objectObj);
  // json_object_set_object_member (rootObj, "event", eventObj);
  
  // if (meta->videoPath)
  //   json_object_set_string_member (rootObj, "videoPath", meta->videoPath);
  // else
  //   json_object_set_string_member (rootObj, "videoPath", "");

• rebuild custom payload for sending messages to kafka

  cd /opt/nvidia/deepstream/deepstream/sources/libs/nvmsgconv \
  && make \
  && cp libnvds_msgconv.so /opt/nvidia/deepstream/deepstream/lib/libnvds_msgconv.so

In L426 of bindschema.cpp , insert the following code before build deepstream python bindings

  .def_readwrite("lc_curr_straight", &NvDsEventMsgMeta::lc_curr_straight)
  .def_readwrite("lc_cum_straight", &NvDsEventMsgMeta::lc_cum_straight);

then build deepstream python bindings and pip install it, more install detail please refer to /docker/Dockerfile

• NVIDIA-AI-IOT/deepstream-occupancy-analytics
• deepstream-test4
• deepstream-nvdsanalytics
• How do I change JSON payload output?
• Problem with reading nvdsanalytics output via Kafka