def read_bb(filename):
    """Read ground truth bounding boxes from file"""

    gt_bboxes = {}
    with open(filename) as file:
        for line in file:
            frame = str(int(line.strip().split(".")[0]))
            bb = line.strip().split(";")[1:6]
            bb = list(map(int, bb))
            if frame in gt_bboxes:
                gt_bboxes[frame].append(bb)
            else:
                gt_bboxes[frame] = [bb]
    return gt_bboxes