inference.py

import tensorflow as tf
import numpy as np
from imgviz import instances2rgb

from configuration import Config

# detections: (classes: list of class_name, boxes: list of [x1, y1, x2, y2])
# actions: list of f'{action_name}: {confidence}'

def format_frame(frame, config: Config):
  frame = tf.image.convert_image_dtype(frame, tf.float32)
  frame = tf.image.resize_with_pad(frame, *config.frame_size)
  return frame

def detect_object(detector, frame):
  result = detector(frame, classes=4, verbose=False)[0]
  classes = result.boxes.cls.numpy()
  boxes = result.boxes.xyxy.numpy()
  detections = (
    [result.names[i].capitalize() for i in classes],
    boxes)
  return detections

def classify_action(classifier, frames, id_to_name):
  actions = []
  frames = np.array(frames)
  frames = tf.expand_dims(frames, 0)
  y = classifier(frames)
  confidences = tf.squeeze(y).numpy()
  for (class_id, confidence) in enumerate(confidences):
    other_class_id = 2
    if confidence > 0.3 and class_id != other_class_id:
      actions.append(f'{id_to_name[class_id]}: {confidence:.2f}')
  return actions

def draw_boxes(frame, detections, actions):
  (classes, boxes) = detections
  max_area = 0
  max_area_id = 0
  for i, box in enumerate(boxes):
    area = (box[3] - box[1]) * (box[2] - box[0])
    if area > max_area:
      max_area = area
      max_area_id = i
  labels = [0 for _ in classes]
  colormap = [(0x39, 0xc5, 0xbb)]
  line_width = 2
  captions = [
    f'{class_name}\n' + '\n'.join(actions if i == max_area_id else [])
    for (i, class_name) in enumerate(classes)]
  bboxes = [
    [box[1], box[0], box[3], box[2]]
    for box in boxes]
  frame = instances2rgb(
    frame,
    labels=labels,
    captions=captions,
    bboxes=bboxes,
    colormap=colormap,
    font_size=20,
    line_width=line_width)
  return frame

def FrameProcessor(detector, classifier, config: Config):
  current_frame = 0
  frames = []
  actions = []
  detections = ([], [])
  def process_frame(frame):
    nonlocal current_frame, frames, actions, detections
    current_frame += 1
    if current_frame % config.classify_action_frame_steps == 0:
      frames.append(format_frame(frame))
    if current_frame % config.detect_object_frame_steps == 0:
      print(f'Detect object: Frame {current_frame}')
      detections = detect_object(detector, frame)
    if len(frames) == config.classify_action_num_frames:
      print(f'Classify action: Until frame {current_frame}')
      actions = classify_action(classifier, frames)
      frames = []
    frame = draw_boxes(frame, detections, actions)
    return frame
  return process_frame