def analyze_posture_by_keypoints(landmarks):
    left_shoulder = landmarks.landmark[11]
    right_shoulder = landmarks.landmark[12]
    left_ear = landmarks.landmark[7]
    right_ear = landmarks.landmark[8]

    shoulder_x = (left_shoulder.x + right_shoulder.x) / 2
    ear_x = (left_ear.x + right_ear.x) / 2

    delta = ear_x - shoulder_x
    if abs(delta) > 0.06:
        return "该用户存在驼背或低头倾向，头部明显前倾。"
    else:
        return "该用户坐姿较为端正，头部与肩部对齐。"