Human Action Recognition with OpenVINO™

This tutorial is also available as a Jupyter notebook that can be cloned directly from GitHub. See the installation guide for instructions to run this tutorial locally on Windows, Linux or macOS. To run without installing anything, click the launch binder button.

This notebook demonstrates live human action recognition with OpenVINO, using the Action Recognition Models from Open Model Zoo, specifically an Encoder and a Decoder. Both models create a sequence to sequence ("seq2seq")1system to identify the human activities for Kinetics-400 dataset. The models use the Video Transformer approach with ResNet34 encoder2. The notebook shows how to create the following pipeline:

Final part of this notebook shows live inference results from a webcam. Additionally, you can also upload a video file.

NOTE: To use a webcam, you must run this Jupyter notebook on a computer with a webcam. If you run on a server, the webcam will not work. However, you can still do inference on a video in the final step.

1 seq2seq: Deep learning models that take a sequence of items to the input and output. In this case, input: video frames, output: actions sequence. This "seq2seq" is composed of an encoder and a decoder. The encoder captures "context" of the inputs to be analyzed by the decoder, and finally gets the human action and confidence.:math:hookleftarrow` <#a1>`__

2 Video Transformer and ResNet34. :math:hookleftarrow` <#a2>`__

Imports

import collections
import os
import sys
import time
from typing import Tuple, List

import cv2
import numpy as np
from IPython import display
from openvino.runtime import Core
from openvino.runtime.ie_api import CompiledModel

sys.path.append("../utils")
import notebook_utils as utils

The models

Download the models

Use omz_downloader, which is a command-line tool from the openvino-dev package. It automatically creates a directory structure and downloads the selected model.

In this case you can use "action-recognition-0001" as a model name, and the system automatically downloads the two models "action-recognition-0001-encoder" and "action-recognition-0001-decoder"

NOTE: If you want to download another model, such as "driver-action-recognition-adas-0002" ("driver-action-recognition-adas-0002-encoder" + "driver-action-recognition-adas-0002-decoder"), replace the name of the model in the code below. Using a model outside the list can require different pre- and post-processing.

# A directory where the model will be downloaded.
base_model_dir = "model"
# The name of the model from Open Model Zoo.
model_name = "action-recognition-0001"
# Selected precision (FP32, FP16, FP16-INT8).
precision = "FP16"
model_path_decoder = (
    f"model/intel/{model_name}/{model_name}-decoder/{precision}/{model_name}-decoder.xml"
)
model_path_encoder = (
    f"model/intel/{model_name}/{model_name}-encoder/{precision}/{model_name}-encoder.xml"
)
if not os.path.exists(model_path_decoder) or not os.path.exists(model_path_encoder):
    download_command = f"omz_downloader " \
                       f"--name {model_name} " \
                       f"--precision {precision} " \
                       f"--output_dir {base_model_dir}"
    ! $download_command

################|| Downloading action-recognition-0001-encoder ||################

========== Downloading model/intel/action-recognition-0001/action-recognition-0001-encoder/FP16/action-recognition-0001-encoder.xml


========== Downloading model/intel/action-recognition-0001/action-recognition-0001-encoder/FP16/action-recognition-0001-encoder.bin


################|| Downloading action-recognition-0001-decoder ||################

========== Downloading model/intel/action-recognition-0001/action-recognition-0001-decoder/FP16/action-recognition-0001-decoder.xml


========== Downloading model/intel/action-recognition-0001/action-recognition-0001-decoder/FP16/action-recognition-0001-decoder.bin

Load your labels

This tutorial uses Kinetics-400 dataset, and also provides the text file embedded into this notebook.

NOTE: If you want to run "driver-action-recognition-adas-0002" model, replace the kinetics.txt file to driver_actions.txt.

labels = "../data/text/kinetics.txt"

with open(labels) as f:
    labels = [line.strip() for line in f]

print(labels[0:9], np.shape(labels))

['abseiling', 'air drumming', 'answering questions', 'applauding', 'applying cream', 'archery', 'arm wrestling', 'arranging flowers', 'assembling computer'] (400,)

Load the models

Load the two models for this particular architecture, Encoder and Decoder. Downloaded models are located in a fixed structure, indicating a vendor, the name of the model, and a precision.

1. Initialize OpenVINO Runtime.

2. Read the network from *.bin and *.xml files (weights and architecture).

3. Compile the model for CPU.

4. Get input and output names of nodes.

Only a few lines of code are required to run the model.

Model Initialization function

# Initialize OpenVINO Runtime.
ie_core = Core()


def model_init(model_path: str) -> Tuple:
    """
    Read the network and weights from a file, load the
    model on CPU and get input and output names of nodes

    :param: model: model architecture path *.xml
    :retuns:
            compiled_model: Compiled model
            input_key: Input node for model
            output_key: Output node for model
    """

    # Read the network and corresponding weights from a file.
    model = ie_core.read_model(model=model_path)
    # Compile the model for CPU (you can use GPU or MYRIAD as well).
    compiled_model = ie_core.compile_model(model=model, device_name="CPU")
    # Get input and output names of nodes.
    input_keys = compiled_model.input(0)
    output_keys = compiled_model.output(0)
    return input_keys, output_keys, compiled_model

Initialization for Encoder and Decoder

# Encoder initialization
input_key_en, output_keys_en, compiled_model_en = model_init(model_path_encoder)
# Decoder initialization
input_key_de, output_keys_de, compiled_model_de = model_init(model_path_decoder)

# Get input size - Encoder.
height_en, width_en = list(input_key_en.shape)[2:]
# Get input size - Decoder.
frames2decode = list(input_key_de.shape)[0:][1]

Helper functions

Use the following helper functions for preprocessing and postprocessing frames:

1. Preprocess the input image before running the Encoder model. (center_crop and adaptative_resize)

2. Decode top-3 probabilities into label names. (decode_output)

3. Draw the Region of Interest (ROI) over the video. (rec_frame_display)

4. Prepare the frame for displaying label names over the video. (display_text_fnc)

def center_crop(frame: np.ndarray) -> np.ndarray:
    """
    Center crop squared the original frame to standardize the input image to the encoder model

    :param frame: input frame
    :returns: center-crop-squared frame
    """
    img_h, img_w, _ = frame.shape
    min_dim = min(img_h, img_w)
    start_x = int((img_w - min_dim) / 2.0)
    start_y = int((img_h - min_dim) / 2.0)
    roi = [start_y, (start_y + min_dim), start_x, (start_x + min_dim)]
    return frame[start_y : (start_y + min_dim), start_x : (start_x + min_dim), ...], roi


def adaptive_resize(frame: np.ndarray, size: int) -> np.ndarray:
    """
     The frame going to be resized to have a height of size or a width of size

    :param frame: input frame
    :param size: input size to encoder model
    :returns: resized frame, np.array type
    """
    h, w, _ = frame.shape
    scale = size / min(h, w)
    w_scaled, h_scaled = int(w * scale), int(h * scale)
    if w_scaled == w and h_scaled == h:
        return frame
    return cv2.resize(frame, (w_scaled, h_scaled))


def decode_output(probs: np.ndarray, labels: np.ndarray, top_k: int = 3) -> np.ndarray:
    """
    Decodes top probabilities into corresponding label names

    :param probs: confidence vector for 400 actions
    :param labels: list of actions
    :param top_k: The k most probable positions in the list of labels
    :returns: decoded_labels: The k most probable actions from the labels list
              decoded_top_probs: confidence for the k most probable actions
    """
    top_ind = np.argsort(-1 * probs)[:top_k]
    out_label = np.array(labels)[top_ind.astype(int)]
    decoded_labels = [out_label[0][0], out_label[0][1], out_label[0][2]]
    top_probs = np.array(probs)[0][top_ind.astype(int)]
    decoded_top_probs = [top_probs[0][0], top_probs[0][1], top_probs[0][2]]
    return decoded_labels, decoded_top_probs


def rec_frame_display(frame: np.ndarray, roi) -> np.ndarray:
    """
    Draw a rec frame over actual frame

    :param frame: input frame
    :param roi: Region of interest, image section processed by the Encoder
    :returns: frame with drawed shape

    """

    cv2.line(frame, (roi[2] + 3, roi[0] + 3), (roi[2] + 3, roi[0] + 100), (0, 200, 0), 2)
    cv2.line(frame, (roi[2] + 3, roi[0] + 3), (roi[2] + 100, roi[0] + 3), (0, 200, 0), 2)
    cv2.line(frame, (roi[3] - 3, roi[1] - 3), (roi[3] - 3, roi[1] - 100), (0, 200, 0), 2)
    cv2.line(frame, (roi[3] - 3, roi[1] - 3), (roi[3] - 100, roi[1] - 3), (0, 200, 0), 2)
    cv2.line(frame, (roi[3] - 3, roi[0] + 3), (roi[3] - 3, roi[0] + 100), (0, 200, 0), 2)
    cv2.line(frame, (roi[3] - 3, roi[0] + 3), (roi[3] - 100, roi[0] + 3), (0, 200, 0), 2)
    cv2.line(frame, (roi[2] + 3, roi[1] - 3), (roi[2] + 3, roi[1] - 100), (0, 200, 0), 2)
    cv2.line(frame, (roi[2] + 3, roi[1] - 3), (roi[2] + 100, roi[1] - 3), (0, 200, 0), 2)
    # Write ROI over actual frame
    FONT_STYLE = cv2.FONT_HERSHEY_SIMPLEX
    org = (roi[2] + 3, roi[1] - 3)
    org2 = (roi[2] + 2, roi[1] - 2)
    FONT_SIZE = 0.5
    FONT_COLOR = (0, 200, 0)
    FONT_COLOR2 = (0, 0, 0)
    cv2.putText(frame, "ROI", org2, FONT_STYLE, FONT_SIZE, FONT_COLOR2)
    cv2.putText(frame, "ROI", org, FONT_STYLE, FONT_SIZE, FONT_COLOR)
    return frame


def display_text_fnc(frame: np.ndarray, display_text: str, index: int):
    """
    Include a text on the analyzed frame

    :param frame: input frame
    :param display_text: text to add on the frame
    :param index: index line dor adding text

    """
    # Configuration for displaying images with text.
    FONT_COLOR = (255, 255, 255)
    FONT_COLOR2 = (0, 0, 0)
    FONT_STYLE = cv2.FONT_HERSHEY_DUPLEX
    FONT_SIZE = 0.7
    TEXT_VERTICAL_INTERVAL = 25
    TEXT_LEFT_MARGIN = 15
    # ROI over actual frame
    (processed, roi) = center_crop(frame)
    # Draw a ROI over actual frame.
    frame = rec_frame_display(frame, roi)
    # Put a text over actual frame.
    text_loc = (TEXT_LEFT_MARGIN, TEXT_VERTICAL_INTERVAL * (index + 1))
    text_loc2 = (TEXT_LEFT_MARGIN + 1, TEXT_VERTICAL_INTERVAL * (index + 1) + 1)
    cv2.putText(frame, display_text, text_loc2, FONT_STYLE, FONT_SIZE, FONT_COLOR2)
    cv2.putText(frame, display_text, text_loc, FONT_STYLE, FONT_SIZE, FONT_COLOR)

AI Functions

Following the pipeline above, you will use the next functions to:

1. Preprocess a frame before running the Encoder. (preprocessing)

2. Encoder Inference per frame. (encoder)

3. Decoder inference per set of frames. (decoder)

4. Normalize the Decoder output to get confidence values per action recognition label. (softmax)

def preprocessing(frame: np.ndarray, size: int) -> np.ndarray:
    """
    Preparing frame before Encoder.
    The image should be scaled to its shortest dimension at "size"
    and cropped, centered, and squared so that both width and
    height have lengths "size". The frame must be transposed from
    Height-Width-Channels (HWC) to Channels-Height-Width (CHW).

    :param frame: input frame
    :param size: input size to encoder model
    :returns: resized and cropped frame
    """
    # Adaptative resize
    preprocessed = adaptive_resize(frame, size)
    # Center_crop
    (preprocessed, roi) = center_crop(preprocessed)
    # Transpose frame HWC -> CHW
    preprocessed = preprocessed.transpose((2, 0, 1))[None,]  # HWC -> CHW
    return preprocessed, roi


def encoder(
    preprocessed: np.ndarray,
    compiled_model: CompiledModel
) -> List:
    """
    Encoder Inference per frame. This function calls the network previously
    configured for the encoder model (compiled_model), extracts the data
    from the output node, and appends it in an array to be used by the decoder.

    :param: preprocessed: preprocessing frame
    :param: compiled_model: Encoder model network
    :returns: encoder_output: embedding layer that is appended with each arriving frame
    """
    output_key_en = compiled_model.output(0)

    # Get results on action-recognition-0001-encoder model
    infer_result_encoder = compiled_model([preprocessed])[output_key_en]
    return infer_result_encoder


def decoder(encoder_output: List, compiled_model_de: CompiledModel) -> List:
    """
    Decoder inference per set of frames. This function concatenates the embedding layer
    froms the encoder output, transpose the array to match with the decoder input size.
    Calls the network previously configured for the decoder model (compiled_model_de), extracts
    the logits and normalize those to get confidence values along specified axis.
    Decodes top probabilities into corresponding label names

    :param: encoder_output: embedding layer for 16 frames
    :param: compiled_model_de: Decoder model network
    :returns: decoded_labels: The k most probable actions from the labels list
              decoded_top_probs: confidence for the k most probable actions
    """
    # Concatenate sample_duration frames in just one array
    decoder_input = np.concatenate(encoder_output, axis=0)
    # Organize input shape vector to the Decoder (shape: [1x16x512]]
    decoder_input = decoder_input.transpose((2, 0, 1, 3))
    decoder_input = np.squeeze(decoder_input, axis=3)
    output_key_de = compiled_model_de.output(0)
    # Get results on action-recognition-0001-decoder model
    result_de = compiled_model_de([decoder_input])[output_key_de]
    # Normalize logits to get confidence values along specified axis
    probs = softmax(result_de - np.max(result_de))
    # Decodes top probabilities into corresponding label names
    decoded_labels, decoded_top_probs = decode_output(probs, labels, top_k=3)
    return decoded_labels, decoded_top_probs


def softmax(x: np.ndarray) -> np.ndarray:
    """
    Normalizes logits to get confidence values along specified axis
    x: np.array, axis=None
    """
    exp = np.exp(x)
    return exp / np.sum(exp, axis=None)

Main Processing Function

Running action recognition function will run in different operations, either a webcam or a video file. See the list of procedures below:

1. Create a video player to play with target fps (utils.VideoPlayer).

2. Prepare a set of frames to be encoded-decoded.

3. Run AI functions

4. Visualize the results.

def run_action_recognition(
    source: str = "0",
    flip: bool = True,
    use_popup: bool = False,
    compiled_model_en: CompiledModel = compiled_model_en,
    compiled_model_de: CompiledModel = compiled_model_de,
    skip_first_frames: int = 0,
):
    """
    Use the "source" webcam or video file to run the complete pipeline for action-recognition problem
    1. Create a video player to play with target fps
    2. Prepare a set of frames to be encoded-decoded
    3. Preprocess frame before Encoder
    4. Encoder Inference per frame
    5. Decoder inference per set of frames
    6. Visualize the results

    :param: source: webcam "0" or video path
    :param: flip: to be used by VideoPlayer function for flipping capture image
    :param: use_popup: False for showing encoded frames over this notebook, True for creating a popup window.
    :param: skip_first_frames: Number of frames to skip at the beginning of the video.
    :returns: display video over the notebook or in a popup window

    """
    size = height_en  # Endoder input size - From Cell 5_9
    sample_duration = frames2decode  # Decoder input size - From Cell 5_7
    # Select frames per second of your source.
    fps = 30
    player = None
    try:
        # Create a video player.
        player = utils.VideoPlayer(source, flip=flip, fps=fps, skip_first_frames=skip_first_frames)
        # Start capturing.
        player.start()
        if use_popup:
            title = "Press ESC to Exit"
            cv2.namedWindow(title, cv2.WINDOW_GUI_NORMAL | cv2.WINDOW_AUTOSIZE)

        processing_times = collections.deque()
        processing_time = 0
        encoder_output = []
        decoded_labels = [0, 0, 0]
        decoded_top_probs = [0, 0, 0]
        counter = 0
        # Create a text template to show inference results over video.
        text_inference_template = "Infer Time:{Time:.1f}ms,{fps:.1f}FPS"
        text_template = "{label},{conf:.2f}%"

        while True:
            counter = counter + 1

            # Read a frame from the video stream.
            frame = player.next()
            if frame is None:
                print("Source ended")
                break

            scale = 1280 / max(frame.shape)

            # Adaptative resize for visualization.
            if scale < 1:
                frame = cv2.resize(frame, None, fx=scale, fy=scale, interpolation=cv2.INTER_AREA)

            # Select one frame every two for processing through the encoder.
            # After 16 frames are processed, the decoder will find the action,
            # and the label will be printed over the frames.

            if counter % 2 == 0:
                # Preprocess frame before Encoder.
                (preprocessed, _) = preprocessing(frame, size)

                # Measure processing time.
                start_time = time.time()

                # Encoder Inference per frame
                encoder_output.append(encoder(preprocessed, compiled_model_en))

                # Decoder inference per set of frames
                # Wait for sample duration to work with decoder model.
                if len(encoder_output) == sample_duration:
                    decoded_labels, decoded_top_probs = decoder(encoder_output, compiled_model_de)
                    encoder_output = []

                # Inference has finished. Display the results.
                stop_time = time.time()

                # Calculate processing time.
                processing_times.append(stop_time - start_time)

                # Use processing times from last 200 frames.
                if len(processing_times) > 200:
                    processing_times.popleft()

                # Mean processing time [ms]
                processing_time = np.mean(processing_times) * 1000
                fps = 1000 / processing_time

            # Visualize the results.
            for i in range(0, 3):
                display_text = text_template.format(
                    label=decoded_labels[i],
                    conf=decoded_top_probs[i] * 100,
                )
                display_text_fnc(frame, display_text, i)

            display_text = text_inference_template.format(Time=processing_time, fps=fps)
            display_text_fnc(frame, display_text, 3)

            # Use this workaround if you experience flickering.
            if use_popup:
                cv2.imshow(title, frame)
                key = cv2.waitKey(1)
                # escape = 27
                if key == 27:
                    break
            else:
                # Encode numpy array to jpg.
                _, encoded_img = cv2.imencode(".jpg", frame, params=[cv2.IMWRITE_JPEG_QUALITY, 90])
                # Create an IPython image.
                i = display.Image(data=encoded_img)
                # Display the image in this notebook.
                display.clear_output(wait=True)
                display.display(i)

    # ctrl-c
    except KeyboardInterrupt:
        print("Interrupted")
    # Any different error
    except RuntimeError as e:
        print(e)
    finally:
        if player is not None:
            # Stop capturing.
            player.stop()
        if use_popup:
            cv2.destroyAllWindows()

Run Action Recognition on a Video File

Find out how the model works in a video file. Any format supported by OpenCV will work. You can press the stop button anytime while the video file is running, and it will activate the webcam for the next step.

NOTE: Sometimes, the video can be cut off if there are corrupted frames. In that case, you can convert it. If you experience any problems with your video, use the HandBrake and select the MPEG format.

video_file = "https://archive.org/serve/ISSVideoResourceLifeOnStation720p/ISS%20Video%20Resource_LifeOnStation_720p.mp4"
run_action_recognition(source=video_file, flip=False, use_popup=False, skip_first_frames=600)

Source ended

Run Action Recognition Using a Webcam

Now, try to see yourself in your webcam.

NOTE: To use a webcam, you must run this Jupyter notebook on a computer with a webcam. If you run on a server, the webcam will not work. However, you can still do inference on a video file in the final step.

run_action_recognition(source=0, flip=False, use_popup=False, skip_first_frames=0)

Cannot open camera 0

[ WARN:0@321.640] global cap_v4l.cpp:982 open VIDEOIO(V4L2:/dev/video0): can't open camera by index
[ERROR:0@321.640] global obsensor_uvc_stream_channel.cpp:156 getStreamChannelGroup Camera index out of range