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17 comments

  • Avatar
    Nx Support

    Sorry Lechee,

    But I did not understand the question. Could you please describe the following in details:

    1. What are you trying to achieve;
    2. How are you trying to do that;
    3. What exactly the problem is;
    4. What is the result you are expecting.

    Thank you.

     

  • Avatar
    lechee lai

    the problem is the AI meta data compute by edge camera which only take 33ms and send the result to stub plugin, but RTSP stream is slow then those meta data, so how to sync with video for example at screenshot I've stand at the position and trigger the meta event but your stub need take 2 second to sync the video person already gone

  • Avatar
    Nx Support

    In this case you need to make sure that timestamps coming from the camera in the rtsp are the same timestamps you use for metadata.

     

    Also, you need to enable 'Trust camera timstamp' in Camera settings dialog -> Expert tab

  • Avatar
    lechee lai

    That's right timestamps can solve the problem, by the way do you have the stub overview or SDK workflow when is the pullMetadataPackets(...) how to trust camera timestamp with/without NTP, when metaData got the timestamp which code is time sync in stub example

  • Avatar
    Nx Support

    >>  how to trust camera timestamp with/without NTP

    Can you please clarify the question? 

     

    >> when metaData got the timestamp which code is time sync in stub example

    Synchronisation doesn't happen in the stub, it happens in the client when it receives video and metadata. Only timestamp is used to synchronise

  • Avatar
    lechee lai

    since timestamp at camera will always slow if only apply NTP in once, in system wide all other metaData won't sync. 

    if sync doesn't happen in the stub, how Can I send the rtps timestamp processVideoFrame(...) with cookSomeObjects() metaData

  • Avatar
    lechee lai

    does it means send correct timestamp in red arrow system will sync the timestamp correctly?

  • Avatar
    Nx Support

    If metadata is going from the camera - this metadata should go with the timestamp associated with it.

    In this case, when creating metadata object - use this timestamp received from camera

     

     

  • Avatar
    lechee lai

    after timestamp associated with meta data still have some offset

  • Avatar
    Nx Support

    Did you set 'trust camera timestamp' in the expert tab of camera settings dialog?

    Also: does your camera has an accurate clock setting?

     

  • Avatar
    lechee lai

    SURE 'trust camera timestamp" is set, by the way how to check clock is accurate, does it means metadata same as RTSP timestamp is fine?

  • Avatar
    Nx Support

    Probably camera's time should be visible somewhere in the camera's web interface.

    Camera's time and server's time should be accurate.

     

  • Avatar
    lechee lai

    yes but it's correct in second NTP server share the same server for NXMeta

  • Avatar
    lechee lai

    when events coming from pullMetadataPackets(...) how to set pre-recording and post-recording 

  • Avatar
    Nx Support

    To be able to set up rules for events - you need to declare custom analytics events in the plugin manifest and send those events when needed.

    Once it is happening - it will be possible to configure actions like camera recording using event rules dialog.

     

     

    About timestamps and synchronization: we are looking into the problem. Probably we will come up with some guidance about debugging them

  • Avatar
    lechee lai

    do you have any reference sample for those plugin manifest

  • Avatar
    Nx Support

    Sure thing.

     

    As an example, you can check out our stub plugin's sources:

    In device_agent.cpp you can find the DeviceAgent::manifest(). It contains the "eventTypes" list.

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