vvas_xoverlay

Overlay plug-in is used for drawing bounding boxes, text, lines, arrows, circles, and polygons on frames. Using display-clock property user can display clock on any part of the frame. This plug-in internally uses vvas_xoverlay library for drawing different shapes, text and clock

For drawing objects like bounding box, lines, arrows etc., the information about these objects must be provided through overlay metadata structure attached to the buffer. For more information about this overlay meta data structure, refer to VVAS Overlay Metadata.

For converting metadata generated from upstream plug-in like infer, opticalflow, segmentation etc., to gstvvasoverlaymeta an intermediate plug-in, vvas_xmetaconvert is to be used before vvas_xoverlay plug-in.

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 text fonts available in opencv
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 buffer formats are RGB/BGR, NV12 and Grayscale. Required metadata in gstvvasoverlaymeta type for drawing.

Control Parameters and Plug-in Properties

The following table lists the GStreamer plug-in properties supported by the vvas_xoverlay plug-in.

Table 7: vvas_xoverlay Plug-in Properties

Property Name	Type	Range	Default	Description
xclbin-location	String	NA	./binary_container_1 .xclbin	location of xcllbin
dev-idx	Integer	0 to 31	0	device index
in-mem-bank	Unsigned int	0 - 65535	0	VVAS input memory bank to allocate memory
display-clock	Boolean	0 or 1	0	flag for indicating displaying clock
clock-fontname	Integer	0 or 7	0	font number for clock based on opencv
clock-fontscale	float	0.1 to 1.0	0.5	font scale of display clock
clock-fontcolor	Integer	0 to 4,294,967,295	0xff00	RGB color of display clock as 0xRGB
clock-xoffset	Integer	0 to frame width	100	x starting position
clock-yoffset	Integer	0 to frame height	50	y starting position

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 VVAS_GstInference data structure. This metadata is parsed and translated into a different metadata structure that understood by vvas_xmetaconvert 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=150528 numbuffers=1
! videoparse width=224 height=224 framerate=30/1 format=16
! vvas_xfilter name="kernel1" kernels-config="<PATH>/kernel_resnet50.json"
! vvas_xmetaconvert config-location="<PATH>/metaconvert.json"
! vvas_xoverlay ! filesink location=output.bgr