Regarding the Message Broker API

[AriTelias]

In UI of the camera: metadata configuration, there is "Analytics Scene Description", but also:
"Axis video motion tracker: Shape"
I want to subscribe specifically to the motion event, from inside my ACAP. Is there a way to do it?
Thank you (ari.telias@aidant.ai)

[Cacsjep]

@AriTelias regarding to docs only scene metadata https://developer.axis.com/acap/api/src/api/message-broker/html/standard_topics.html but what you exaclty need, may there is a other way like using Object analytics or scene description

[AriTelias]

Hello Cacjsep, thanks for your reply.

1. When I run the sample application, I get back the error:
   Got subscription error Failed registering subscriber: (sdk::1.5318 - test_topic/1): Unauthorized

I get this error with the com.axis.analytics_scene_description.v0.beta topic as well.

What kind of authorization is needed by the subscriber, and how to add it?

2. I need to detect motion without VMD running, if possible. I could use the VMD events instead of message broker, but that will tie my ACAP to VMD which is not professional. The current message broker will send scene data only when a known object is detected, not motion. I assume its possible due to the UI of the camera: "metadata configuration/Axis video motion tracker: Shape"

[Cacsjep]

There is no auth

[Cacsjep]

I think motion tracker is a topic for axis internals otherwise it would be exposed

[Cacsjep]

When you completely need simple motion just build a simple pixel motion detector. Or look with metadata Monitor may an metadata event is generated even no object analytics is running

[AriTelias]

Yes, that's exactly what I used - only I put this code inside my own application, adapting the 'main' part accordingly, as there is already a main in my app. But the message broker part is exactly the same , and it tells me I am unauthorized.

[Cacsjep]

Yes, that's exactly what I used - only I put this code inside my own application, adapting the 'main' part accordingly, as there is already a main in my app. But the message broker part is exactly the same , and it tells me I am unauthorized.

That's strange which firmware ?

[AriTelias]

I could build a simple motion detector of course, I was just hoping that I can reuse the one already built and tried by AXIS..... Also, the performance hit is big - optimizations are required to effectively detect motion in high res images. And there is a service already running inside the camera, would be wasteful not to reuse it...

[Cacsjep]

Completely understand, there is no documentation about that tracker, so I don't know how it works or even at which resolution, try out metadata monitor may produced events there, then you could subscribe to them

[AriTelias]

Harware in tis case: Q1728
Yes, the metadata from VMD is indeed available, so I could do that, but as you know, it required VMD running otherwise no metadata comes out. Not optimal, but I will go that way if I dont figure out the MetadatBroker issue. Do you hav evisibility into the file mdb/subscriber_config.h> Maybe it has a hint into the error message. It's not in GitHub....

[Cacsjep]

Also here no Infos about that https://www.axis.com/developer-community/scene-metadata-integration yeah but did you try disable all to see, may that this scene tracker produce also events ? You could look into to docker there are the headers file, I use mdb eserval times and never see this issue. May update firmware or you are already on latest 12.x ?

[AriTelias]

Firmware is 12.2.52. Ill keep trying...

[Cacsjep]

Also for futher discussion you could join my discord channel for acap:) https://discord.gg/zF6mhmPajB

[Cacsjep]

They mdb was also for me sometimes not useable the scene topic has 1-2 seconds delay so keep this in mind

[Cacsjep]

@AriTelias #215 (comment)