Overview

The qtivoverlay element is a hardware-accelerated, in-place drawing and blitting plugin designed to render visual overlay objects directly on top of incoming video frames, such as YUV or RGB buffers. By compositing overlays directly onto the frame data, it enables the processed video to be displayed on a screen or forwarded for encoding with minimal additional overhead. This makes it well suited for real-time video applications where performance and low latency are important. The element supports a wide range of overlay content, including user-defined graphics and annotations such as logos, bounding boxes, custom labels, date and time, buffer timestamps, privacy masks, and other visual indicators. In addition, qtivoverlay can render dynamic overlay information carried in GstMeta, which is commonly used to attach AI or analytics results to each frame for post-processing and visualization. To achieve efficient overlay rendering, qtivoverlay combines CPU-based drawing with GPU-based blending:

CPU rendering with Cairo: Overlay content is first drawn using the open-source Cairo graphics library into compact, memory-efficient overlay buffers.
GPU hardware blending: These rendered overlay buffers are then blended with the main video frame using GPU hardware acceleration.

This hybrid approach helps reduce memory usage and improves overall performance, especially in pipelines handling high-resolution or high-frame-rate video streams. The overlays supported by the element can be described in two ways: Through element properties These are overlays configured manually by the user, including:

Static images or logos
Bounding boxes
Date and/or time
Buffer timestamps
Custom text
Privacy masks

Through buffer metadata These overlays are attached to each input frame as metadata, and are typically added by the qtimetamux plugin. This metadata is used to draw machine-learning-related overlays such as:

Detection overlays, including bounding boxes
Segmentation overlays, such as semantic masks or mask images
Classification overlays, such as labels or user text
Pose graph overlays

In summary, qtivoverlay is a hardware-accelerated, in-place image drawing and blitting plugin for overlaying visual annotations on video frames. It supports both manually configured overlays and metadata-driven overlays, making it suitable for use cases such as video analytics, AI inference visualization, and privacy masking.

Example Pipeline

Download Required Files

File	Download	Save as
YOLOX W8A8 model	Qualcomm AI Hub — YOLOX	`yolo_x_w8a8.tflite`
Detection labels	yolov8.json	`yolov8.json`
Sample video	Input video	`ai_demo_sample.mp4`

Copy files to device

# Replace $HOME to the appropriate device path before running the commands.
# For QLI:    /root
# For Ubuntu: /home/ubuntu
# Modify this based on your platform and ensure files are copied to the correct location on the device.
# Run from your host machine — replace <user> and <device-ip>

ssh <user>@<device-ip> "mkdir -p $HOME/{models,labels,media,media/output}"
scp yolo_x_w8a8.tflite          <user>@<device-ip>:$HOME/models/
scp yolov8.json                  <user>@<device-ip>:$HOME/labels/
scp ai_demo_sample.mp4   <user>@<device-ip>:$HOME/media/

Connect to device

# Run from your host machine — replace <user> and <device-ip>
ssh <user>@<device-ip>

Set environment variables

Run below command on your device

mkdir -p $HOME/{models,labels,media,media/output}
export MODEL_NAME=yolo_x_w8a8.tflite
export LABELS_NAME=yolov8.json
export SRC_VIDEO_NAME=ai_demo_sample.mp4

Run the pipeline

gst-launch-1.0 -e --gst-debug=2 \
filesrc location=$HOME/media/$SRC_VIDEO_NAME ! qtdemux ! h264parse ! \
v4l2h264dec capture-io-mode=4 output-io-mode=4 ! video/x-raw,format=NV12 ! queue ! \
tee name=t ! qtimetamux name=obj_mux ! qtivoverlay ! waylandsink fullscreen=true sync=false \
t. ! queue ! qtimlvconverter ! queue ! \
qtimltflite model=$HOME/models/$MODEL_NAME delegate=external external-delegate-path=libQnnTFLiteDelegate.so \
  external-delegate-options="QNNExternalDelegate,backend_type=htp,log_level=(string)1;" ! queue ! \
qtimlpostprocess module=yolov8 labels=$HOME/labels/$LABELS_NAME \
  settings="{\"confidence\": 51.0}" ! text/x-raw ! queue ! obj_mux.

Hierarchy

GObject
   GstObject
      GstElement
         GstBaseTransform
            qtivoverlay

Pad Templates

sink

Capabilities
`video/x-raw`	`format: { NV12, NV21, YUY2, RGBA, BGRA, ARGB, ABGR, RGBx, BGRx, xRGB, xBGR, RGB, BGR, NV12_Q08 }` `width: [1, 2147483647]` `height: [1, 2147483647]` `framerate: [0/1, 2147483647/1]`
Availability: Always
Direction: sink

src

Capabilities
`video/x-raw`	`format: { NV12, NV21, YUY2, RGBA, BGRA, ARGB, ABGR, RGBx, BGRx, xRGB, xBGR, RGB, BGR, NV12_Q08 }` `width: [1, 2147483647]` `height: [1, 2147483647]` `framerate: [0/1, 2147483647/1]`
Availability: Always
Direction: source

Element Properties

Property	Description
`bboxes`	Manually set multiple custom bounding boxes as a list of GstStructures with a unique name and three parameters: `position`, `dimensions`, and `color`. The `position` and `dimensions` are mandatory for new entries. `Type: String` `Default: "{ }"` `Flags: readable/writable` `Example:` `{(structure)\"Box1,position=<100,100>,dimensions=<640,480>;\", (structure)\"Box2,position=<1000,100>,dimensions=<300,300>,color=0xFF0000FF;\"}`
`images`	Manually set multiple custom BGRA images as a list of GstStructures with a unique name and three mandatory parameters: `path`, `resolution`, and `destination`. `Type: String` `Default: "{ }"` `Flags: readable/writable` `Example:` `{(structure)\"Image1,path=/data/image1.bgra,resolution=<480,360>,destination=<0,0,640,480>;\", (structure)\"Image2,path=/data/image2.bgra,resolution=<240,180>,destination=<100,100,480,360>;\"}`
`masks`	Manually set multiple masks as a list of GstStructures with a unique name and parameters `color` and either `circle=<X, Y, RADIUS>` or `rectangle=<X, Y, WIDTH, HEIGHT>` (polygon also supported). `Type: String` `Default: "{ }"` `Flags: readable/writable` `Example:` `{(structure)\"Mask1,color=0xRRGGBBAA,circle=<400,400,200>;\",(structure)\"Mask2,color=0xRRGGBBAA,rectangle=<0,0,20,10>;\",(structure)\"Mask3,color=0xRRGGBBAA,polygon=<<2,2>,<2,4>,<4,4>>;\"}`
`strings`	Manually set multiple custom strings as a list of GstStructures with a unique name and four parameters: `contents`, `fontsize`, `position`, and `color`. The `contents` field is mandatory for new entries. `Type: String` `Default: "{ }"` `Flags: readable/writable` `Example:` `{(structure)\"Text1,contents=\\\"Example\ 1\\\",fontsize=12,position=<0,0>,color=0xRRGGBBAA;\"}`
`timestamps`	Manually set timestamps using GstStructures. Use `Date/Time` for displaying formatted date and time with optional parameters `format`, `fontsize`, `position`, and `color`. Use `PTS/DTS` for displaying buffer timestamps with optional parameters `fontsize`, `position`, and `color`. `Type: String` `Default: "{ }"` `Flags: readable/writable` `Example:` `{(structure)\"Date/Time,format=\\\"%d/%m/%Y\ %H:%M:%S\\\",fontsize=12,position=<0,0>,color=0xRRGGBBAA;\", (structure)\"PTS/DTS,fontsize=12,position=<0,0>,color=0xRRGGBBAA;\}`

Metadata (AI Post-Process Information)

Incoming video buffers may contain additional metadata in the form of GstMeta. The element inspects each buffer for supported metadata types and renders any detected metadata directly on top of the corresponding image frame. Each supported metadata type is processed and displayed according to its own visual representation.

Supported Metadata Types

GstVideoRegionOfInterestMeta

This metadata describes a region of interest (ROI) within the frame, typically representing an object such as a person, vehicle, keyboard, or any other detected item. A rectangle is drawn around the ROI using the specified X/Y coordinates, width, and height. The rectangle is rendered with a visible border and a transparent interior so that the object inside the region remains visible.

GstVideoLandmarksMeta

This metadata describes a collection of landmark points that may represent human pose key-points, facial features, hand joints, or other connected points of interest. Both the individual points and the lines connecting related points are drawn on the image, allowing the landmark structure to be visualized clearly.

GstVideoClassificationMeta

This metadata contains a list of possible labels or classifications for the entire image. All associated labels are rendered in the top-left corner of the frame, making the classification results easy to view at a glance.

GstCvOptclFlowMeta

This metadata represents optical flow motion vectors, which describe the movement between pixels across two sequential video frames. The vectors indicate motion direction and magnitude, making it useful for visualizing frame-to-frame movement in the video stream.

User-Defined Overlay Objects via Properties

In addition to buffer metadata, the plugin supports user-defined overlay objects that can be configured through properties. These overlays can be added, updated, or removed during runtime. Once configured, each overlay remains visible on every incoming video frame until the user explicitly removes it.

Supported Property Types

Static Images

Static images such as logos, icons, or watermarks can be added using the images property. All images provided through this property must be in raw RGBA format. The property payload follows the GStreamer structure layout and requires the following mandatory parameters when first set:

Parameter	Description
`path`	URL or path to the image file
`resolution`	Width and height of the image in pixels
`destination`	Top-left X/Y coordinates where the image should be placed, along with its final rendered size

"{(structure)"Image1,path=/data/logo1.rgba,resolution=<480,360>,destination=<0,0,640,480>;", (structure)"Image2,path=/data/logo2.rgba,resolution=<240,180>,destination=<100,100,480,360>;"}"

	Description
Image1	Resolution 480×360, destination coordinates X=0, Y=0, rendered size 640×480
Image2	Resolution 240×180, destination coordinates X=100, Y=100, rendered size 480×360

Custom Text

Text overlays such as captions, titles, annotations, or labels can be set using the strings property. The property payload follows the GStreamer structure layout and requires the following parameters when first set:

Parameter	Description
`contents`	Text content to be displayed
`fontsize`	Font size of the text
`position`	Top-left X/Y coordinates where the text should appear
`color`	Text color in RGBA hex format

"{(structure)"Text1,contents=\"Example 1\",fontsize=48,position=<50,50>,color=0x0000FFFF;", (structure)"Text2,contents=\"Example 2\",fontsize=64,position=<1620,520>,color=0xFF0000FF;"}"

	Description
Text1	Font size 48, position X=50, Y=50, blue color
Text2	Font size 64, position X=1620, Y=520, red color

Timestamps

Timestamps such as the current date/time or buffer timestamps can be displayed using the timestamps property. The property payload follows the GStreamer structure layout and requires the following parameters when first set:

Parameter	Description
`format`	Date/time formatting string. Not applicable for `PTS/DTS`
`fontsize`	Font size of the timestamp
`position`	Top-left X/Y coordinates where the timestamp should be placed
`color`	Timestamp color in RGBA hex format

"{(structure)"Date/Time,format=\"%d/%m/%Y %H:%M:%S\",fontsize=48,position=<50,50>,color=0xFFFFFFFF;", (structure)"PTS/DTS,fontsize=64,position=<50,920>,color=0xFF0000FF;"}"

	Description
Date/Time	Format DAY/MONTH/YEAR HOUR:MIN:SEC, font size 48, position X=50, Y=50, white color
PTS/DTS	Buffer timestamp, font size 64, position X=50, Y=920, red color

Privacy Masks

Privacy masks can be used to obscure specific portions of the image using the masks property. The property payload follows the GStreamer structure layout and requires a unique name along with a color value and one of the supported shape definitions:

Shape	Syntax	Description
`circle`	`circle=<X, Y, RADIUS>`	Draws a circular mask centered at the specified X/Y position with the given radius
`rectangle`	`rectangle=<X, Y, WIDTH, HEIGHT>`	Draws a rectangular mask using the specified coordinates and dimensions
`polygon`	`polygon=<X1, Y1, X2, Y2, X3, Y3, ...>`	Draws a polygonal mask defined by multiple coordinate points

Additional parameter:

Parameter	Description
`color`	Mask color in RGBA hex format

"{(structure)"Mask2,color=0xFF0000FF,circle=<1520,730,50>;", (structure)"Mask1,color=0x0000FFFF,rectangle=<1280,860,100,150>;", (structure)"Mask3,color=0x00FF00FF,polygon=<<910,510>,<860,740>,<1140,760>,<1160,520>>;"}"

	Description
Mask2	Red circle mask — X=1520, Y=730, R=50
Mask1	Blue rectangle mask — X=1280, Y=860, Width=100, Height=150
Mask3	Green polygon mask — points: (910,510), (860,740), (1140,760), (1160,520)

Bounding Boxes

Rectangles used to highlight a region or object within the frame can be configured using the bboxes property. The property payload follows the GStreamer structure layout and requires the following parameters when first set:

Parameter	Description
`position`	Top-left X/Y coordinates where the rectangle should be placed
`dimensions`	Width and height of the rectangle
`color`	Rectangle color in RGBA hex format

"{(structure)"Box1,position=<100,100>,dimensions=<640,480>;", (structure)"Box2,position=<1000,100>,dimensions=<300,300>,color=0xFF0000FF;"}"

	Description
Box1	Position X=100, Y=100, size 640×480
Box2	Position X=1000, Y=100, size 300×300, red color

Usage

User-Defined Overlays with Live Camera Preview

Sample pipeline displaying user-defined text positioned at the top-left corner of the video frames (live preview from camera), along with a circular privacy mask applied to conceal a selected region of the image.

gst-launch-1.0 -e --gst-debug=2 \
qticamsrc ! video/x-raw,format=NV12,width=1920,height=1080,framerate=30/1 ! queue ! \
qtivoverlay \
masks='{(structure)"Mask1,color=0xff0011ff,inverse=false,circle=<500,500,50>;"}' \
strings='{(structure)"Text1,contents=\"Example\ 1\",fontsize=40,position=<0,0>,color=0xFF00FFFF;"}' \
! queue ! waylandsink fullscreen=true sync=false

Single-Stage AI Inference with Overlay

Sample pipeline containing a single stage AI inference that performs object detection on the video frame. The AI stage generates ROI metadata in string format and attaches it to the main frame. This metadata is then rendered as an overlay using the qtivoverlay plugin and displayed on the output video.

Download Required Files

File	Download	Save as
YOLOX W8A8 model	Qualcomm AI Hub — YOLOX	`yolox_w8a8.tflite`
Detection labels	yolov8.json	`yolov8.json`

If any downloaded file is a .zip archive, extract it on your host machine before copying: unzip filename.zip

Copy files to device

# Run from your host machine — replace <user> and <device-ip>
ssh <user>@<device-ip> "mkdir -p $HOME/{models,labels}"
scp yolox_w8a8.tflite   <user>@<device-ip>:$HOME/models/
scp yolov8.json         <user>@<device-ip>:$HOME/labels/

Connect to device

# Run from your host machine — replace <user> and <device-ip>
ssh <user>@<device-ip>

Set environment variables

Run below command on your device

mkdir -p $HOME/{models,labels}
export MODEL_NAME=yolox_w8a8.tflite
export LABELS_NAME=yolov8.json

Run the pipeline

gst-launch-1.0 -e --gst-debug=2 \
qticamsrc ! video/x-raw,format=NV12,width=1920,height=1080,framerate=30/1 ! queue ! tee name=t_split \
t_split. ! queue ! metamux. \
t_split. ! queue ! qtimlvconverter ! queue ! qtimltflite model=$HOME/models/$MODEL_NAME delegate=external external-delegate-path=libQnnTFLiteDelegate.so external-delegate-options="QNNExternalDelegate,backend_type=htp,log_level=(string)1;" ! queue ! qtimlpostprocess results=6 module=yolov8 labels=$HOME/labels/$LABELS_NAME ! text/x-raw ! queue ! metamux. \
qtimetamux name=metamux ! queue ! qtivoverlay ! queue ! waylandsink fullscreen=true sync=false

Applying a Static Image as Overlay

This pipeline demonstrates how to blit a static image (e.g., a company logo or watermark) onto a live video stream using the images property of qtivoverlay. The image is loaded once at pipeline start and composited onto every frame at the specified position and size.

The image file must be in raw BGRA format. Save your image as logo.bgra before running this pipeline.

Prepare Required Files

File	Description	Save as
Logo image	Raw BGRA format image file (e.g., your company logo or watermark)	`logo.bgra`

Copy files to device

# Run from your host machine — replace <user> and <device-ip>
ssh <user>@<device-ip> "mkdir -p $HOME/media"
scp logo.bgra  <user>@<device-ip>:$HOME/media/

Connect to device

# Run from your host machine — replace <user> and <device-ip>
ssh <user>@<device-ip>

Set environment variables

Run below command on your device

mkdir -p $HOME/media

Run the pipeline

gst-launch-1.0 -e --gst-debug=2 \
qticamsrc ! video/x-raw,format=NV12,width=1920,height=1080,framerate=30/1 ! \
qtivoverlay \
images='{(structure)"Image1,path=$HOME/media/logo.bgra,resolution=<480,360>,destination=<0,0,640,480>;"}' \
! waylandsink fullscreen=true sync=false

Parameter	Value	Notes
`path`	`$HOME/media/logo.bgra`	Absolute path to the raw BGRA image file
`resolution`	`<480,360>`	Original width × height of the source image
`destination`	`<0,0,640,480>`	X, Y position and rendered width × height

Applying Timestamp — DD/MM/YY and Time as Text Overlay

This pipeline demonstrates how to render the current date in DD/MM/YYYY format and the current time as a live text overlay on each video frame using the timestamps property of qtivoverlay. The timestamp is updated automatically on every buffer.

gst-launch-1.0 -e \
qticamsrc ! video/x-raw,format=NV12,width=1920,height=1080,framerate=30/1 ! \
qtivoverlay \
timestamps='{(structure)"Date/Time,format=\"%d/%m/%Y\ %H:%M:%S\",fontsize=60,position=<200,200>,color=0xFFFFFFFF;"}' \
! waylandsink sync=false fullscreen=true

Parameter	Value	Notes
`format`	`%d/%m/%Y %H:%M:%S`	Day/Month/Year Hour:Min:Sec — e.g., `16/04/2025 14:35:07`
`fontsize`	`60`	Font size in points
`position`	`<200,200>`	X, Y pixel coordinates on the frame
`color`	`0xFFFFFFFF`	White text in RGBA hex format

Applying Circular and Rhombus Privacy Masks

This pipeline demonstrates how to apply multiple privacy masks of different shapes — a circle and a rhombus (polygon) — to obscure sensitive regions of the video frame using the masks property of qtivoverlay. Both masks are rendered simultaneously on every frame.

gst-launch-1.0 -e --gst-debug=2 \
qticamsrc ! video/x-raw,format=NV12,width=1920,height=1080,framerate=30/1 ! \
qtivoverlay \
masks='{(structure)"Mask1,color=0xff0011ff,inverse=false,circle=<500,500,50>;",(structure)"Mask2,color=0xff0011f0,polygon=<<100,50>,<150,100>,<100,150>,<50,100>>;"}' \
! waylandsink sync=false fullscreen=true

Mask	Shape	Parameters	`color`	Notes
Mask 1	`circle`	`circle=<500,500,50>`, `inverse=false`	`0xff0011ff`	Circle at center X=500, Y=500, R=50
Mask 2	`polygon`	`polygon=<<100,50>,<150,100>,<100,150>,<50,100>>`	`0xff0011f0`	Rhombus defined by four corner points

Multiple masks can be combined in a single masks property by listing multiple GStreamer structures separated by commas. Each mask is rendered independently and can use a different shape, position, and color.

​Overview

​Example Pipeline

​Hierarchy

​Pad Templates

​sink

​src

​Element Properties

​Metadata (AI Post-Process Information)

​Supported Metadata Types

​GstVideoRegionOfInterestMeta

​GstVideoLandmarksMeta

​GstVideoClassificationMeta

​GstCvOptclFlowMeta

​User-Defined Overlay Objects via Properties

​Supported Property Types

​Static Images

​Custom Text

​Timestamps

​Privacy Masks

​Bounding Boxes

​Usage

​User-Defined Overlays with Live Camera Preview

​Single-Stage AI Inference with Overlay

​Applying a Static Image as Overlay

​Applying Timestamp — DD/MM/YY and Time as Text Overlay

​Applying Circular and Rhombus Privacy Masks

Overview

Example Pipeline

Hierarchy

Pad Templates

sink

src

Element Properties

Metadata (AI Post-Process Information)

Supported Metadata Types

GstVideoRegionOfInterestMeta

GstVideoLandmarksMeta

GstVideoClassificationMeta

GstCvOptclFlowMeta

User-Defined Overlay Objects via Properties

Supported Property Types

Static Images

Custom Text

Timestamps

Privacy Masks

Bounding Boxes

Usage

User-Defined Overlays with Live Camera Preview

Single-Stage AI Inference with Overlay

Applying a Static Image as Overlay

Applying Timestamp — DD/MM/YY and Time as Text Overlay

Applying Circular and Rhombus Privacy Masks