vvas_xoverlay

The Overlay plug-in is utilized to draw shapes like bounding boxes, lines, arrows, circles, and polygons on a given frame or image. Users can display a clock on any part of the frame by using the display-clock property. This plug-in employs the VVAS Core Overlay library to produce different shapes, text, and clocks.

The overlay metadata structure, GstVvasOverlayMeta, must be used to provide the information about the objects like, bounding boxes, lines, and arrows to be drawn. This metadata must be attached to the input buffer. For more details about this overlay metadata structure, please refer VVAS Overlay Metadata section.

To convert metadata generated from an upstream plug-in such as vvas_xinfer, vvas_xoptflow, or segmentation into GstVvasOverlayMeta, an intermediate plug-in called vvas_xmetaconvert is provided and this can be used before the vvas_xoverlay plug-in in gstreamer pipeline.

For implementation details, refer to vvas_xoverlay source code

Supported features

Feature	Description
boxes	Drawing bounding boxes with and without background color
text	Overlaying of text with and without background color. Supports initial 5 of the Hershey fonts in OpenCv (SIMPLEX, PLAIN, DUPLEX, COMPLEX, TRIPLEX).
lines	For drawing lines with different thickness and color
arrows	Drawing arrows on either side of line or both the sides
circle	For drawing circles of different radius and thickness without fill
polygons	For drawing closed polygons without fill

Input and Output

Supported input video formats are RGB, BGR, NV12 and Grayscale. Required metadata in gstvvasoverlaymeta type for drawing.

Example Pipelines

The following example demonstrates use of vvas_xoverlay plug-in with vvas_xinfer and vvas_xmetaconvert plug-ins for drawing bounding boxes. vvas_xinfer plug-in produces inference result and stores in GstInferenceMeta structure. This metadata is parsed and translated into GstVvasOverlayMeta structure that is understood by vvas_xoverlay plug-in to draw the bounding box. This translation of meta data is done by vvas_xmetaconvert plug-in.

gst-launch-1.0 filesrc location="<PATH>/001.bgr" blocksize=519168 numbuffers=1
! videoparse width=416 height=416 framerate=30/1 format=16
! vvas_xinfer preprocess-config="<PATH>/ppe_yolov3_voc_imgproc0.json" infer-config="<PATH>/infer_yolov3_voc.json"
! vvas_xmetaconvert config-location="<PATH>/metaconvert.json"
! vvas_xoverlay ! filesink location=output.bgr