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Hailo Aggregator

Overview

HailoAggregator is an element designed for applications with cascading networks or cropping functionality, meaning doing one task based on a previous task. A complement to the HailoCropper, the two elements work together to form versatile apps. It has 2 sink pads and 1 source: the first sinkpad receives the original frame from an upstream hailocropper, while the other receives cropped buffers from that hailocropper. The HailoAggregator waits for all crops of a given orignal frame to arrive, then sends the original buffer with the combined metadata of all collected crops.

HailoAggregator also performs a 'flattening' functionality on the detection metadata when receiving each frame: detections are taken from the cropped frame, copied to the main frame and re-scaled/moved to their corresponding location in the main frame (x,y,width,height). As an example:

  • Face Landmarks based on Face Detection - HailoCropper crops each face detection -> HailoNet + FaceLandmarks post for each face -> HailoAggregator aggregates the frames back.
  • Tiling - hailotilecropper crops the image to tiles -> HailoNet + Detection post for each tile -> HailoAggregator aggregates the frames back and 'flatten` the detection objects in the metadata.

HailoAggregator exports two methods to extend or override in derived elements:

  • handle_sub_frame_roi: Functionality to perform for each incoming sub frame.

    Calls `flattening` method.

  • post_aggregation: Functionality to perform after all frames are aggregated succesfully.

    Base implementation does nothing.

Parameters

There are no unique properties to hailoaggregator. The only parameters are the baseclass parameters, which are 'name' and 'parent'.

Example

../resources/cascading.png

Hierarchy

GObject
 +----GInitiallyUnowned
       +----GstObject
             +----GstElement
                   +----GstHailoAggregator

Pad Templates:
  SRC template: 'src'
    Availability: Always
    Capabilities:
      ANY

  SINK template: 'sink'
    Availability: Always
    Capabilities:
      ANY

Element has no clocking capabilities.
Element has no URI handling capabilities.

Pads:
  SINK: 'sink_0'
    Pad Template: 'sink'
  SINK: 'sink_1'
    Pad Template: 'sink'
  SRC: 'src'
    Pad Template: 'src'

Element Properties:
  name                : The name of the object
                        flags: readable, writable
                        String. Default: "hailoaggregator0"
  parent              : The parent of the object
                        flags: readable, writable
                        Object of type "GstObject"
  flatten-detections  : perform a 'flattening' functionality on the detection metadata
                        when receiving each frame.
                        flags: readable, writable, changeable only in NULL or READY state
                        Boolean. Default: false