Tutorial#

In this tutorial, you will learn how to build video analytics pipelines using Intel® Deep Learning Streamer (Intel® DL Streamer) Pipeline Framework.

About GStreamer#

In this section we introduce basic GStreamer* concepts that you will use in the rest of the tutorial. If you are already familiar with GStreamer feel free to skip ahead to the next section - Introduction to Intel® DL Streamer Pipeline Framework.

GStreamer is a flexible, fast and multiplatform open-source multimedia framework. It has an easy to use command line tool for running pipelines, as well as an API with bindings in C*, Python*, Javascript* and more. In this tutorial we will use the GStreamer command line tool gst-launch-1.0. For more information and examples please refer to the online documentation for gst-launch-1.0.

Pipelines#

The command line tool gst-launch-1.0 enables developers to describe a media analytics pipeline as a series of connected elements. The list of elements, their configuration properties, and their connections are all specified as a list of strings separated by exclamation marks (!). gst-launch-1.0 parses the string and instantiates the software modules which perform the individual media analytics operations. Internally, the GStreamer library constructs a pipeline object that contains the individual elements and handles common operations such as clocking, messaging, and state changes.

Example: gst-launch-1.0 videotestsrc ! ximagesink

Elements#

An element is the fundamental building block of a pipeline. Elements perform specific operations on incoming frames and then push the resulting frames downstream for further processing. Elements are linked together textually by exclamation marks (!) with the full chain of elements representing the entire pipeline. Each element will take data from its upstream element, process it and then output the data for processing by the next element.

Elements designated as source elements provide input into the pipeline from external sources. In this tutorial we use the filesrc element that reads input from a local file.

Elements designated as sink elements represent the final stage of a pipeline. As an example, a sink element could write transcoded frames to a file on the local disk or open a window to render the video content to the screen or even restream the content via RTSP. We will use the standard xvimagesink element to render the video frames on a local display.

We will also use the decodebin utility element. The decodebin element constructs a concrete set of decode operations based on the given input format and the decoder and demuxer elements available in the system. At a high level, the decodebin abstracts the individual operations required to take encoded frames and produce raw video frames suitable for image transformation and inferencing.

Properties#

Elements are configured using key-value pairs called properties. As an example, the filesrc element has a property named location which specifies the file path for input.

Example: filesrc location=cars_1900.mp4

The documentation for each element, which can be viewed using the command line tool gst-inspect-1.0, describes its properties as well as the valid range of values for each property.

Introduction to Intel® Deep Learning Streamer (Intel® DL Streamer) Pipeline Framework#

Intel® DL Streamer Pipeline Framework is an easy way to construct media analytics pipelines using Intel® Distribution of OpenVINO™ toolkit. It leverages the open source media framework GStreamer to provide optimized media operations and Deep Learning Inference Engine from OpenVINO™ Toolkit to provide optimized inference.

The elements packaged in the Intel® DL Streamer Pipeline Framework binary release can be divided into three categories:

  • Elements for optimized streaming media operations (usb and ip camera support, file handling, decode, color-space-conversion, scaling, encoding, rendering, etc.). These elements are developed by the larger GStreamer community.

  • Elements that use the Deep Learning Inference Engine from OpenVINO™ Toolkit or OpenCV for optimized video analytics (detection, classification, tracking). These elements are provided as part of the Pipeline Framework’s GVA plugin.

  • Elements that convert and publish inference results to the screen as overlaid bounding boxes, to a file as a list of JSON Objects, or to popular message brokers (Kafka or MQTT) as JSON messages. These elements are provided as part of the DL Streamer’s GVA plugin.

The elements in the last two categories above are part of Pipeline Framework’s GVA plugin and start with the prefix ‘gva’. We will describe the ‘gva’ elements used in this tutorial with some important properties here. Refer to Intel DL Streamer elements page for more details.

  • gvadetect - Runs detection with the Inference Engine from OpenVINO™ Toolkit. We will use it to detect vehicles in a frame and output their bounding boxes aka Regions of Interest (ROI).

    • model - path to the inference model network file

    • device - device to run inferencing on

    • inference-interval - interval between inference requests, the bigger the value, the better the throughput. i.e. setting this property to 1 would mean run detection on every frame while setting it to 5 would run detection on every fifth frame.

  • gvaclassify - Runs classification with the Inference Engine from OpenVINO™ Toolkit. We will use it to label the bounding boxes that gvadetect outputs, with the type and color of the vehicle.

    • model - path to the inference model network file

    • model-proc - path to the model-proc file. A model-proc file describes the model input and output layer format. The model-proc file in this tutorial describes the output layer name and labels (person and vehicle) of objects it detects. See model-proc for more information.

    • device - device to run inferencing on

  • gvatrack - Identifies objects in frames where detection is skipped and assigns unique ID to objects. This allows us to run object detection on fewer frames and increases overall throughput while still tracking the position and type of objects in every frame.

  • gvawatermark - Overlays detection and classification results on top of video data. We will do exactly that. Parse the detected vehicle results metadata and create a video frame rendered with the bounding box aligned to the vehicle position; parse the classified vehicle result and label it on the bounding box.

In addition to gvadetect and gvaclassify, you can use gvainference for running inference with any CNN model not supported by gvadetect or gvaclassify. Also, instead of visualizing the inference results, as shown in this tutorial, you can publish them to MQTT, Kafka or a file using gvametaconvert and gvametapublish of Intel DL Streamer.

Tutorial Setup#

  1. Install Intel® Deep Learning Streamer (Intel® DL Streamer) Pipeline Framework by following the Install-Guide.

  2. Set the environment variables:

    source /opt/intel/openvino_2022/setupvars.sh
    source /opt/intel/dlstreamer/setupvars.sh
    

    Note

    You must set the environment variables each time you open a new shell unless you added the variables to the .bashrc file. See Set the environment variables.

  3. Download the models from Open Model Zoo

    python3 -m pip install --upgrade pip
    python3 -m pip install openvino-dev[onnx]
    /opt/intel/dlstreamer/samples/download_models.sh
    
  4. Export the model and model_proc files for detection and classification:

    export DETECTION_MODEL=${MODELS_PATH}/intel/person-vehicle-bike-detection-2004/FP32/person-vehicle-bike-detection-2004.xml
    export DETECTION_MODEL_PROC=/opt/intel/dlstreamer/samples/model_proc/intel/person-vehicle-bike-detection-2004.json
    export VEHICLE_CLASSIFICATION_MODEL=${MODELS_PATH}/intel/vehicle-attributes-recognition-barrier-0039/FP32/vehicle-attributes-recognition-barrier-0039.xml
    export VEHICLE_CLASSIFICATION_MODEL_PROC=/opt/intel/dlstreamer/samples/model_proc/intel/vehicle-attributes-recognition-barrier-0039.json
    

    If you want to use your own models, you need to first convert them in the IR (Intermediate Representation) format. For detailed instructions to convert models, look here

  5. Export the video file path:

    You may download a sample video from the here. If you provide your own video file as an input, please make sure that it is in h264 or mp4 format. You can also download and use freely licensed content from the websites such as Pexels*. Any video with cars, or pedestrians can be used with the exercise.

    # This tutorial uses ~/path/to/video as the video path
    # and FILENAME as the placeholder for a video file name.
    # Change this information to fit your setup.
    export VIDEO_EXAMPLE=~/path/to/video/FILENAME
    

Exercise 1 - Build object detection pipeline#

This exercise helps you create a GStreamer pipeline that will perform object detection using gvadetect element and Intermediate Representation (IR) formatted object detection model. It provides two optional add-ons to show you how to use video from a web camera stream and an RTSP URI.

This exercise introduces you to using the following Pipeline Framework elements:

  • gvadetect

  • gvawatermark

Pipeline#

We will create a pipeline to detect people and vehicles in a video. The pipeline will accept a video file input, decode it and run vehicle detection. It will overlay the bounding boxes for detected vehicles on the video frame and render the video to local device.

Run the below pipeline at the command prompt and review the output:

gst-launch-1.0 \
filesrc location=${VIDEO_EXAMPLE} ! decodebin ! \
gvadetect model=${DETECTION_MODEL} model_proc=${DETECTION_MODEL_PROC} device=CPU ! queue ! \
gvawatermark ! videoconvert ! fpsdisplaysink video-sink=xvimagesink sync=false

Expected output: You will see your video overlayed by bounding boxes around persons, vehicles, and bikes.

In addition to the elements described in the first two section, the pipeline uses `fpsdisplaysink` to display the average FPS of the pipeline.

You’re done building and running this pipeline. To expand on this exercise, use one or both add-ons to this exercise to select different video sources. If the add-ons don’t suit you, jump ahead to start Exercise 2.

Pipeline with a Web Camera Video Stream Input (First optional add-on to Exercise 1)#

GStreamer supports connected video devices, like web cameras, which means you use a web camera to perform real-time inference.

In order to use web camera as an input, we will replace the filesrc element in the object detection pipeline with `v4l2src` element, that is used for capturing video from webcams. Before running the below updated pipeline, check the web camera path and update it in the pipeline. The web camera stream is usually in the /dev/ directory.

Object detection pipeline using Web camera:

# Change <path-to-device> below to your web camera device path
gst-launch-1.0 \
v4l2src device=<path-to-device> ! decodebin ! \
gvadetect model=${DETECTION_MODEL} model_proc=${DETECTION_MODEL_PROC} device=CPU ! queue ! \
gvawatermark ! videoconvert ! fpsdisplaysink video-sink=xvimagesink sync=false

Pipeline with an RTSP Input (Second optional add-on to Exercise 1)#

In order to use RTSP source as an input, we will replace the filesrc element in the object detection pipeline with `urisourcebin` to access URIs. Before running the below updated pipeline, replace ‘<RTSP_uri>’ with your RTSP URI and verify it before running the command.

Object detection pipeline using RTSP URI:

# Change <RTSP_uri> below to your RTSP URL
gst-launch-1.0 \
urisourcebin uri=<RTSP_uri> ! decodebin ! \
gvadetect model=${DETECTION_MODEL} model_proc=${DETECTION_MODEL_PROC} device=CPU ! queue ! \
gvawatermark ! videoconvert ! fpsdisplaysink video-sink=xvimagesink sync=false

Exercise 2: Build object classification pipeline#

This exercise helps you create a GStreamer pipeline that will perform object classification on the Regions of Interest (ROIs) detected by gvadetect using gvaclassify element and Intermediate Representation (IR) formatted object classification model.

This exercise uses the following Pipeline Framework elements:

  • gvadetect

  • gvaclassify

  • gvawatermark

Pipeline#

We will create a pipeline to detect people and vehicles in a video and classify the detected people and vehicle to provide additional attributes.

Run the below pipeline at the command prompt and review the output:

gst-launch-1.0 \
filesrc location=${VIDEO_EXAMPLE} ! decodebin ! \
gvadetect model=${DETECTION_MODEL} model_proc=${DETECTION_MODEL_PROC} device=CPU ! queue ! \
gvaclassify model=${VEHICLE_CLASSIFICATION_MODEL} model-proc=${VEHICLE_CLASSIFICATION_MODEL_PROC} device=CPU object-class=vehicle ! queue ! \
gvawatermark ! videoconvert ! fpsdisplaysink video-sink=xvimagesink sync=false

Expected output: Persons, vehicles, and bikes are bound by colored boxes, and detection results as well as classification attributes such as vehicle type and color are displayed as video overlays.

In the above pipeline:

  1. gvadetect detects the ROIs in the video and outputs ROIs with the appropriate attributes (person, vehicle, bike) according to its model-proc.

  2. gvadetect ROIs are used as inputs for the gvaclassify model.

  3. gvaclassify classifies the ROIs and outputs additional attributes according to model-proc:

    • object-class tells gvalcassify which ROIs to classify.

    • object-class=vehicle classifies ROIs with ‘vehicle’ attribute only.

  4. gvawatermark displays the ROIs and their attributes.

See model-proc for the model-procs and its input and output specifications.

Exercise 3: Use object tracking to improve performance#

This exercise helps you create a GStreamer pipeline that will use object tracking for reducing the frequency of object detection and classification, thereby increasing the throughput, using gvatrack.

This exercise uses the following Pipeline Framework elements:

  • gvadetect

  • gvaclassify

  • gvatrack

  • gvawatermark

Pipeline#

We will use the same pipeline as in exercise 2, for detecting and classifying vehicle and people. We will add gvatrack element after gvadetect and before gvaclassify to track objects. gvatrack will assign object IDs and provide updated ROIs in between detections. We will also specify parameters of gvadetect and gvaclassify elements to reduce frequency of detection and classification.

Run the below pipeline at the command prompt and review the output:

gst-launch-1.0 \
filesrc location=${VIDEO_EXAMPLE} ! decodebin ! \
gvadetect model=${DETECTION_MODEL} model_proc=${DETECTION_MODEL_PROC} device=CPU inference-interval=10 ! queue ! \
gvatrack tracking-type=short-term-imageless ! queue ! \
gvaclassify model=${VEHICLE_CLASSIFICATION_MODEL} model-proc=${VEHICLE_CLASSIFICATION_MODEL_PROC} device=CPU object-class=vehicle reclassify-interval=10 ! queue ! \
gvawatermark ! videoconvert ! fpsdisplaysink video-sink=xvimagesink sync=false

Expected output: Persons, vehicles, and bikes are bound by colored boxes, and detection results as well as classification attributes such as vehicle type and color are displayed as video overlays, same as exercise 2. However, notice the increase in the FPS of the pipeline.

In the above pipeline:

  1. gvadetect detects the ROIs in the video and outputs ROIs with the appropriate attributes (person, vehicle, bike) according to its model-proc on every 10th frame, due to inference-interval=10.

  2. gvatrack tracks each object detected by gvadetect.

  3. gvadetect ROIs are used as inputs for the gvaclassify model.

  4. gvaclassify classifies the ROIs and outputs additional attributes according to model-proc, but skips classification for already classified objects for 10 frames, using tracking information from gvatrack to determine whether to classify an object:

    • object-class tells gvaclassify which ROIs to classify.

    • object-class=vehicle classifies ROIs that have the ‘vehicle’ attribute.

    • reclassify-interval determines how often to reclassify tracked objects. Only valid when used in conjunction with gvatrack.

  5. gvawatermark displays the ROIs and their attributes.

You’re done building and running this pipeline. The next exercise shows you how to publish your results to a .json.

Exercise 4: Publish Inference Results#

This exercise extends the pipeline to publish your detection and classification results to a .json file from a GStreamer pipeline.

This exercise uses the following Pipeline Framework elements:

  • gvadetect

  • gvaclassify

  • gvametaconvert

  • gvametapublish

Setup#

One additional setup step is required for this exercise, to export the output file path:

# Replace <path-to-FILENAME> with path to your file before running the below command.
export OUTFILE=<path-to-FILENAME>

Pipeline#

We will use the same pipeline as in exercise 2 for detecting and classifying vehicle and people. However, instead of overlaying the results and rendering them to a screen, we will send them to a file in JSON format.

Run the below pipeline at the command prompt and review the output:

gst-launch-1.0 \
filesrc location=${VIDEO_EXAMPLE} ! decodebin ! \
gvadetect model=${DETECTION_MODEL} model_proc=${DETECTION_MODEL_PROC} device=CPU ! queue ! \
gvaclassify model=${VEHICLE_CLASSIFICATION_MODEL} model-proc=${VEHICLE_CLASSIFICATION_MODEL_PROC} device=CPU object-class=vehicle ! queue ! \
gvametaconvert format=json ! \
gvametapublish method=file file-path=${OUTFILE} ! \
fakesink

Expected output: After the pipeline completes, a JSON file of the inference results is available. Review the JSON file.

In the above pipeline:

  • gvametaconvert uses the optional parameter format=json to convert inferenced data to GstGVAJSONMeta.

  • GstGVAJSONMeta is a custom data structure that represents JSON metadata.

  • gvametapublish uses the optional parameter method=file to publish inference results to a file.

  • filepath=${OUTFILE} is a JSON file to which the inference results are published.

For publishing the results to MQTT or Kafka, please refer to the metapublish samples.

You have completed this tutorial. Now, start creating your video analytics pipeline with Intel® DL Streamer Pipeline Framework!

Next Steps#


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