Face recognition using deepface shows error "NoneType has no len()"

Question

This is my code I've been working on:

cap=cv2.VideoCapture(1)
if not cap.isOpened():
    cap=cv2.VideoCapture(0)
if not cap.isOpened():
    raise IOError("cannot open webcam")
faceCascade = cv2.CascadeClassifier(cv2.data.haarcascades+"haarcascade_frontalface_default.xml")
while True:
    ret,frame=cap.read()
    result= DeepFace.analyze(frame, actions = ['emotion'])
    gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
    faces = faceCascade.detectMultiScale(gray, scaleFactor=1.05, minNeighbors=5)
    for x, y, w, h in faces:
        cv2.rectangle(frame, (x, y), (x + w, y + h), (66, 50, 200), 6)
    font = cv2.FONT_HERSHEY_SIMPLEX
    cv2.putText(frame,
                result["dominant_emotion"],
                (100, 200),
                font, 10,
                (0, 0, 255),
                10,
                cv2.LINE_4);
    cv2.imshow("Original Video", frame)

    if cv2.waitKey(2) & 0xFF==ord('q'):
        break

cap.release()
cv2.destroyAllWindows()

The error I'm facing while running the code:

TypeError                                 Traceback (most recent call last)
<ipython-input-5-e9c622d7a86c> in <module>
      7 while True:
      8     ret,frame=cap.read()
----> 9     result= DeepFace.analyze(frame, actions = ['emotion'])
     10     gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
     11     faces = faceCascade.detectMultiScale(gray, scaleFactor=1.05, minNeighbors=5)

~\Anaconda3\lib\site-packages\deepface\DeepFace.py in analyze(img_path, actions, models, enforce_detection, detector_backend, prog_bar)
    389                         if action == 'emotion':
    390                                 emotion_labels = ['angry', 'disgust', 'fear', 'happy', 'sad', 'surprise', 'neutral']
--> 391                                 img, region = functions.preprocess_face(img = img_path, target_size = (48, 48), grayscale = True, enforce_detection = enforce_detection, detector_backend = detector_backend, return_region = True)
    392 
    393                                 emotion_predictions = models['emotion'].predict(img)[0,:]

~\Anaconda3\lib\site-packages\deepface\commons\functions.py in preprocess_face(img, target_size, grayscale, enforce_detection, detector_backend, return_region, align)
    173 
    174         #img might be path, base64 or numpy array. Convert it to numpy whatever it is.
--> 175         img = load_image(img)
    176         base_img = img.copy()
    177 

~\Anaconda3\lib\site-packages\deepface\commons\functions.py in load_image(img)
     72                 exact_image = True
     73 
---> 74         elif len(img) > 11 and img[0:11] == "data:image/":
     75                 base64_img = True
     76 

TypeError: object of type 'NoneType' has no len()

Answer 1

If you read the traceback, cap.read() has returned a null frame. You should check the documentation to see why this may be.

You can workaround the issue by checking its value, and raising your own error.

ret,frame=cap.read()
if frame is None:
    raise ValueError('Unable to get a frame!')
result= DeepFace.analyze(frame, actions = ['emotion'])