OpenCV问题：FileNotFoundError: [WinError 2] 系统找不到指定的文件

Question

我刚接触OpenCV和Python，并通过在线教程成功安装了它们。现在我正在尝试运行以下脚本：

from scipy.spatial import distance as dist
from imutils.video import VideoStream
from imutils import face_utils
from threading import Thread
import numpy as np
import argparse
import imutils
import time
import dlib
import cv2
import subprocess
def sound_alarm(path):
# play an alarm sound
subprocess.call(["afplay",path])

def eye_aspect_ratio(eye):
A = dist.euclidean(eye[1], eye[5])
B = dist.euclidean(eye[2], eye[4])
C = dist.euclidean(eye[0], eye[3])
ear = (A + B) / (2.0 * C)
return ear

   ap = argparse.ArgumentParser()
   ap.add_argument("-p", "--shape-predictor", required=True,
   help="path to facial landmark predictor")
   ap.add_argument("-a", "--alarm", type=str, default="",
    help="path alarm .WAV file")
   ap.add_argument("-w", "--webcam", type=int, default=0,
    help="index of webcam on system")
   args = vars(ap.parse_args())

   EYE_AR_THRESH = 0.25
   EYE_AR_CONSEC_FRAMES = 10
   COUNTER = 0
   ALARM_ON = False

   print("[INFO] loading facial landmark predictor...")
   detector = dlib.get_frontal_face_detector()
   predictor = dlib.shape_predictor(args["shape_predictor"])

(lStart, lEnd) = face_utils.FACIAL_LANDMARKS_IDXS["left_eye"]
(rStart, rEnd) = face_utils.FACIAL_LANDMARKS_IDXS["right_eye"]

print("[INFO] starting video stream thread...")
vs = VideoStream(src=args["webcam"]).start()
time.sleep(1.0)

while True:
    frame = vs.read()
    frame = imutils.resize(frame, width=450)
    gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
    rects = detector(gray, 0)
    for rect in rects:
        shape = predictor(gray, rect)
        shape = face_utils.shape_to_np(shape)
        leftEye = shape[lStart:lEnd]
        rightEye = shape[rStart:rEnd]
        leftEAR = eye_aspect_ratio(leftEye)
        rightEAR = eye_aspect_ratio(rightEye)
        ear = (leftEAR + rightEAR) / 2.0
        leftEyeHull = cv2.convexHull(leftEye)
        rightEyeHull = cv2.convexHull(rightEye)
        cv2.drawContours(frame, [leftEyeHull], -1, (0, 255, 0), 1)
        cv2.drawContours(frame, [rightEyeHull], -1, (0, 255, 0), 1)
        if ear < EYE_AR_THRESH:
            COUNTER += 1
            if COUNTER >= EYE_AR_CONSEC_FRAMES:
                if not ALARM_ON:
                    ALARM_ON = True
                    if args["alarm"] != "":
                        t = Thread(target=sound_alarm,
                            args=(args["alarm"],))
                        t.deamon = True
                        t.start()
                cv2.putText(frame, "DROWSINESS ALERT!", (10, 30),
                    cv2.FONT_HERSHEY_SIMPLEX, 0.7, (0, 0, 255), 2)
        else:
            COUNTER = 0
            ALARM_ON = False
        cv2.putText(frame, "EAR: {:.2f}".format(ear), (300, 30),
            cv2.FONT_HERSHEY_SIMPLEX, 0.7, (0, 0, 255), 2)

    cv2.imshow("Frame", frame)
    key = cv2.waitKey(1) & 0xFF
    if key == ord("q"):
        break

cv2.destroyAllWindows()
vs.stop()

脚本可以正常运行，但我遇到以下问题:

1) 没有按照触发条件（alarm.wav）发出警报声音。

2) 在执行此脚本时:

python detect_drowsiness.py --shape-predictor 
shape_predictor_68_face_landmarks.dat --alarm alarm.wav

我收到了以下错误信息。

Exception in thread Thread-1:
Traceback (most recent call last):
  File "C:\Users\Mandeesh\AppData\Local\Programs\Python\Python37- 
   32\lib\threading.py", line 917, in _bootstrap_inner
        self.run()
  File "C:\Users\Mandeesh\AppData\Local\Programs\Python\Python37-
32\lib\threading.py", line 865, in run
    self._target(*self._args, **self._kwargs)
  File "detect_drowsiness.py", line 18, in sound_alarm
    subprocess.call(["afplay",path])
   File "C:\Users\Mandeesh\AppData\Local\Programs\Python\Python37- 
   32\lib\subprocess.py", line 317, in call
    with Popen(*popenargs, **kwargs) as p:
  File "C:\Users\Mandeesh\AppData\Local\Programs\Python\Python37- 
   32\lib\subprocess.py", line 769, in __init__
    restore_signals, start_new_session)
  File "C:\Users\Mandeesh\AppData\Local\Programs\Python\Python37- 
   32\lib\subprocess.py", line 1172, in _execute_child
    startupinfo)
 FileNotFoundError: [WinError 2] The system cannot find the file specified

我完全不了解opencv和python，尝试为朋友的项目尝试这个脚本。有人能帮忙提出潜在问题吗？

- Mandeesh Singh

Answer 1

谢谢，问题已解决。我试图在Windows上运行MACOS函数“afplay”。使用“playsound”修改了脚本，声音可以正常触发！

谢谢。

- Mandeesh Singh

Answer 2

欢迎来到Stackoverflow！

错误发生的原因是您的脚本没有将正确的文件路径传递给sound_alarm(path)函数。

请检查包含以下内容的行：

                    if args["alarm"] != "":
                    t = Thread(target=sound_alarm,
                        args=(args["alarm"],))
                    t.deamon = True
                    t.start() 

如果您在使用sound_alarm(path)时遇到问题，我建议首先使用单独的脚本编写一个简单的函数来测试您的警报是否能够播放，以便确定问题所在。

您可以尝试以下代码：

import subprocess
path = r'C:\your_file_path_here'
def sound_alarm(path):
    # play an alarm sound
    print ('entered function')
    subprocess.call(["afplay",path])
    print ('ended function')
sound_alarm(path)

如果您在控制台中打印了entered function和ended function，但仍然没有声音播放，那么这意味着subprocess.call在处理文件播放声音时存在问题，这意味着调用文件的代码有误并需要重新编写或文件本身存在问题。

- ycx