python - PiCameraValueError : Incorrect buffer length for resolution 1920x1080

Question

这是我检测圆/球的代码。我想从 Pi 相机检测足球。 (足球可以是任何颜色。)我遇到了一些 PiCameraValueError 的问题。这段代码有什么问题。我正在使用 Raspberry Pi 2、Python2 和 OpenCV。

from picamera.array import PiRGBArray
from picamera import PiCamera
import time
import cv2
import sys
import imutils
import cv2.cv as cv
# initialize the camera and grab a reference to the raw camera capture
camera = PiCamera()

rawCapture = PiRGBArray(camera)

# capture frames from the camera
for frame in camera.capture_continuous(rawCapture, format="bgr"):
    # grab the raw NumPy array representing the image, then initialize the timestamp
    # and occupied/unoccupied text
    image = frame.array
    img   = cv2.medianBlur(image, 5)
    imgg  = cv2.cvtColor(img, cv2.COLOR_RGB2GRAY)
    cimg  = cv2.cvtColor(imgg, cv2.COLOR_GRAY2BGR)
    imgg  = cv2.blur(imgg, (3,3))
            #imgg = cv2.dilate(imgg, np.ones((5, 5)))
            #imgg = cv2.GaussianBlur(imgg,(5,5),0)
    circles = cv2.HoughCircles(imgg, cv.CV_HOUGH_GRADIENT, 1, 20, param1=100, param2=40, minRadius=5, maxRadius=90)
    cv2.imshow("cimg", imgg)
    key = cv2.waitKey(1)
    if key & 0xFF == ord('q'):
        break
    if circles is None:
        continue

    print circles
            #circles = np.uint16(np.around(circles))
    for i in circles[0,:]:
        cv2.circle(cimg,(i[0],i[1]),i[2],(0,255,0),1) # draw the outer circle
                   #cv2.circle(cimg,(i[0],i[1]),2,(0,0,255),3) # draw the center of the circle
        cv2.imshow("Filtered", cimg)

cv2.destroyWindow("cimg")
cv2.destroyAllWindows() 

Answer 1

如解释here ,

the PiCameraValueError is a secondary exception raised in response to the KeyboardInterrupt exception. This is quite normal and not a bug (it's more a consequence of how generic the output mechanism is in picamera), but it is difficult to detect and respond to in Python 2 (the usual method there would probably be to catch the PiCameraValueError as well in whatever loop your main script runs). Under Python 3, exception chaining is implemented so you could potentially look back through the stack of exceptions to find the KeyboardInterrupt one.

您需要做的是清除捕获之间的流。 PiRGBArray文档涵盖了使用截断函数执行此操作。

这是来自 python face detection raspberry pi with picamera 的示例

import io
import time
import picamera
with picamera.PiCamera() as camera:
    stream = io.BytesIO()
    for foo in camera.capture_continuous(stream, format='jpeg'):
    # YOURS:  for frame in camera.capture_continuous(stream, format="bgr",  use_video_port=True):
        # Truncate the stream to the current position (in case
        # prior iterations output a longer image)
        stream.truncate()
        stream.seek(0)
        if process(stream):
            break