Get tracks using GO

To get tracks using GO, do the following:

Install GO (see Go programming language).

Run the code example:

client := metadata.NewMetadataServiceClient(conn)

stream, err := client.PullMetadata(context.Background())
ch := make(chan int, 8)

go func() {
  for {
    in, err := stream.Recv()
    if err == io.EOF {
      close(ch)
      return
    }

    if err != nil {
      log.Fatal(err)
    }

    switch data := in.Data.(type) {
      case *metadata.PullMetadataResponse_Heartbeat:
      //
      case *metadata.PullMetadataResponse_ConfigUpdate:
      //
      case *metadata.PullMetadataResponse_Sample:
      switch sampleData := data.Sample.Data.(type) {
        case *metadata.MetadataSample_Tracklets:
        log.Printf("Time: %v\nTracklets: %v", data.Sample.Timestamp, sampleData.Tracklets)
      }
    }

    ch <- 1 // notify the main thread about receiving the sample
  }
}()

endpoint := media.EndpointRef{AccessPoint: "hosts/SERVER/AVDetector.1/SourceEndpoint.vmda"}
req := metadata.PullMetadataRequest{
  Count:                 8, // ask for several samples, so that they are not lost while server waits for another response from client
  Endpoint:              &endpoint,
  ProposedChannelIdleMs: 15000,
}

if err := stream.Send(&req); err != nil {
  log.Fatal(err)
}

for {
  // whenever a sample is received ask for another sample keeping the total samples requested to a fixed value > 1
  <-ch 
  req := metadata.PullMetadataRequest{
    Count: 1,
  }

  if err := stream.Send(&req); err != nil {
    log.Fatal(err)
  }
}

As a result, you will get the possible response options.

Response examples:

Message about the received tracks:

{
  "sample": {
    "timestamp": "20230914T133656.981000",
    "tracklets": {
      "tracklets": [
        {
          "id": 70,
          "state": "OBJECT_STATE_NORMAL",
          "rectangle": {
            "x": 0.10248079895973206,
            "y": 0.3568287789821625,
            "w": 0.17517775297164917,
            "h": 0.257714182138443
          },
          "logicalCenter": {
            "x": 0.19006967544555664,
            "y": 0.6145429611206055
          },
          "color": {
            "hue": 222.47191011235952,
            "saturation": 0.3093524946210368,
            "value": 0.49719319611902735
          }
        }
      ]
    }
  }
}

where

timestamp—time corresponding to the video frame for which tracks are formed;
tracklets—list of tracks.

Message about the Server activity when the Server has no other messages:

{

  "heartbeat": {}

}

Message about the time during which the Server is active and you can receive data from it:

{
  "configUpdate": {
    "maxChannelIdleMs": 15000
  }
}

Page tree

Documentation for Axxon One 2.0. Documentation for other versions of Axxon One is available too.