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This project makes use of Yolo v4 and the Darknet framework. Nowadays there more efficient and precise ways to perform object inference with GStreamer, for instance by using Nvidia Deepstream with Yolo v5, YOLO-R, etc. I suggest you to take a look at these.

gst-darknet

gst-darknet is a GStreamer plugin that allows to use Darknet (neural network framework) inside GStreamer, to perform object detection against video files or real-time streams. For instance, the video above was generated with the following command:

gst-launch-1.0 \
filesrc location=test.mp4 ! decodebin ! videoconvert \
! darknetinfer config=yolov4.cfg weights=yolov4.weights \
! darknetrender labels=coco.names \
! videoconvert \
! xvimagesink sync=1

The plugin provides these elements:

• darknetinfer, that runs Darknet against one or multiple input videos
• darknetprint, that prints the detected objects to stdout
• darknetrender, that draws the detected objects on the input video

Installation

1. Install CUDA Toolkit.

2. Install build dependencies:

   sudo apt update && sudo apt install -y \
   git \
   make \
   pkg-config \
   g++ \
   libgstreamer-plugins-base1.0-dev \
   libcairo2-dev

3. Clone the repository, enter into the folder:

   git clone https://github.com/aler9/gst-darknet \
   && cd gst-darknet

4. Compile and install:

   make -j$(nproc) \
   && sudo make install

Basic usage

1. Download config, weights, class labels and a sample video:

   wget https://raw.githubusercontent.com/AlexeyAB/darknet/master/cfg/yolov4.cfg \
   && wget https://github.com/AlexeyAB/darknet/releases/download/darknet_yolo_v3_optimal/yolov4.weights \
   && wget https://raw.githubusercontent.com/AlexeyAB/darknet/master/data/coco.names \
   && wget https://raw.githubusercontent.com/aler9/gst-darknet/master/test/test.mp4

2. Launch the pipeline:

   gst-launch-1.0 \
   filesrc location=test.mp4 ! decodebin ! videoconvert \
   ! darknetinfer config=yolov4.cfg weights=yolov4.weights \
   ! darknetrender labels=coco.names \
   ! videoconvert \
   ! xvimagesink sync=1

   If the platform is a Nvidia Jetson:

   gst-launch-1.0 \
   filesrc location=test.mp4 ! decodebin ! nvvideoconvert ! videoconvert \
   ! darknetinfer config=yolov4.cfg weights=yolov4.weights \
   ! darknetrender labels=coco.names \
   ! videoconvert \
   ! xvimagesink sync=1

Advanced usage and FAQs

Use a RTSP stream instead of a file

Launch the pipeline:

gst-launch-1.0 \
rtspsrc location=rtsp://myurl:554/mypath ! decodebin ! videoconvert \
! darknetinfer config=yolov4.cfg weights=yolov4.weights \
! darknetrender labels=coco.names \
! videoconvert \
! xvimagesink sync=1

Print detections to stdout

Launch the pipeline:

gst-launch-1.0 \
filesrc location=test.mp4 ! decodebin ! videoconvert \
! darknetinfer config=yolov4.cfg weights=yolov4.weights \
! darknetprint labels=coco.names \
! fakesink

Save video with detections to disk

Launch the pipeline:

gst-launch-1.0 \
filesrc location=test.mp4 ! decodebin ! videoconvert \
! darknetinfer config=yolov4.cfg weights=yolov4.weights \
! darknetrender labels=coco.names \
! videoconvert \
! x264enc \
! mp4mux \
filesink location=output.mp4

Process multiple inputs at once

Launch the pipeline:

gst-launch-1.0 \
darknetinfer name=d config=yolov4.cfg weights=yolov4.weights \
multifilesrc location=dog.jpg caps="image/jpeg,framerate=20/1" ! jpegdec ! videoconvert \
! d.sink_0 d.src_0 ! darknetrender labels=coco.names ! videoconvert ! xvimagesink sync=1 \
multifilesrc location=giraffe.jpg caps="image/jpeg,framerate=20/1" ! jpegdec ! videoconvert \
! d.sink_1 d.src_1 ! darknetrender labels=coco.names ! videoconvert ! xvimagesink sync=1

Element documentation

darknetinfer properties:

• gpu-id: GPU to use for inference (default is 0)
• config: path to a Darknet config file
• weights: path to a Darknet weights file
• probability-threshold: probability threshold of detected objects (default is 0.7)
• nms-threshold: NMS threshold of detected objects (default is 0.45)
• print-fps: periodically print FPS to stdout (default is TRUE)
• print-fps-period: Period of FPS printing in seconds (default is 5)

darknetprint properties:

• labels: path to a label file

darknetrender properties:

• labels: path to a label file
• box-color: color of the boxes in HTML format (default is 00FFFF)
• text-color: color of the text in HTML format (default is 000000)

Export detections

One of the ways to export detections consists in launching GStreamer through a C program that makes use of the GStreamer API. The detections are then available in a C struct (GstDarknetMetaDetection) and can be exported in any desired way.

1. Copy examples/export.c in an empty folder, edit to suit needs.

2. Compile (replace /path-to-gst-darknet):

   gcc -Ofast -Werror -Wall -Wextra -Wno-unused-parameter \
   -I/path-to-gst-darknet \
   export.c -o export \
   $(pkg-config --cflags --libs gstreamer-app-1.0)

3. Launch:

   ./export

Links

• Darknet (AlexeyAB) https://github.com/AlexeyAB/darknet
• Darknet (pjreddie) https://github.com/pjreddie/darknet