python - 使用opencv+picamera stream IO用树莓派抓取视频

Question

我正在使用 Raspberry 来简单地显示一个视频(目前只是这个)。为此，我必须使用 opencv (cv2)。我尝试了很多解决方案，但现在我想使用 Picamera 库捕获视频。我会告诉你我的代码:

import io
import time
import picamera
import cv2
import numpy as np

# Create the in-memory stream
stream = io.BytesIO()
with picamera.PiCamera() as camera:
    while True:
        camera.capture(stream, format='jpeg')
        # Construct a numpy array from the stream
        data = np.fromstring(stream.getvalue(), dtype=np.uint8)
        # "Decode" the image from the array, preserving colour
        image = cv2.imdecode(data, 1)
        cv2.imshow('frame', image)

如你所见，它真的很简单，但它不起作用。实际上它并没有打开 window 。我想重现下一个完美运行的行为:

#import numpy as np
import cv2

cap = cv2.VideoCapture(0)

while(True):
    # Capture frame-by-frame
    ret, frame = cap.read()
    cv2.imshow('frame',frame)
    if cv2.waitKey(1) & 0xFF == ord('q'):
        break

# When everything done, release the capture
cap.release()
cv2.destroyAllWindows()

有什么想法吗？

Answer 1

查看 this blog posting .它具有实现此功能的代码:

# import the necessary packages
from picamera.array import PiRGBArray
from picamera import PiCamera
import time
import cv2

# initialize the camera and grab a reference to the raw camera capture
camera = PiCamera()
rawCapture = PiRGBArray(camera)

# allow the camera to warmup
time.sleep(0.1)

# grab an image from the camera
camera.capture(rawCapture, format="bgr")
image = rawCapture.array

# display the image on screen and wait for a keypress
cv2.imshow("Image", image)
cv2.waitKey(0)

再往下有一个连续捕捉图像的例子。

# import the necessary packages
from picamera.array import PiRGBArray
from picamera import PiCamera
import time
import cv2

# initialize the camera and grab a reference to the raw camera capture
camera = PiCamera()
camera.resolution = (640, 480)
camera.framerate = 32
rawCapture = PiRGBArray(camera, size=(640, 480))

# allow the camera to warmup
time.sleep(0.1)

# capture frames from the camera
for frame in camera.capture_continuous(rawCapture, format="bgr", use_video_port=True):
    # grab the raw NumPy array representing the image, then initialize the timestamp
    # and occupied/unoccupied text
    image = frame.array

    # show the frame
    cv2.imshow("Frame", image)
    key = cv2.waitKey(1) & 0xFF

    # clear the stream in preparation for the next frame
    rawCapture.truncate(0)

    # if the `q` key was pressed, break from the loop
    if key == ord("q"):
        break