如何在不下载的情况下从 Google Cloud Storage 读取视频？ 使用视频网址

Question

我想使用 opencv 读取视频文件，但问题是视频在我的 Google Cloud Storage 上，而opencv.videocapture方法无法识别它。 有没有其他方法可以在不下载本地磁盘上的视频的情况下访问视频文件？

我也尝试过urllib.urlopen但它没有用。 这是我的代码：

import urllib
import numpy as np
import cv2

uri = 'gs://call-gestures/dictionany/AIDS.mp4'
url = "https://storage.cloud.google.com/call- 
gestures/dictionany/AIDS.mp4?authuser=1"
# Open a sample video available in sample-videos
r = cv2.imread(url)
print('Result: ',r)
cap = cv2.VideoCapture(url)
print(cap)
if cap.isOpened():
    print ("File Can be Opened")
    while(True):
        # Capture frame-by-frame
        ret, frame = cap.read()
        #print cap.isOpened(), ret
        if frame is not None:
            # Display the resulting frame
            cv2.imshow('frame',frame)
            # Press q to close the video windows before it ends if you want
            if cv2.waitKey(22) & 0xFF == ord('q'):
                break
        else:
            print("Frame is None")
            break

    # When everything done, release the capture
    cap.release()
    cv2.destroyAllWindows()
    print ("Video stop")
else:
    print("Not Working")

我得到的错误：

warning: Error opening file (/build/opencv/modules/videoio/src/cap_ffmpeg_impl.hpp:901)
warning: https://storage.cloud.google.com/call-gestures/dictionany/Asia.mp4?authuser=1 (/build/opencv/modules/videoio/src/cap_ffmpeg_impl.hpp:902)

Answer 1

是的，有一种方法可以通过生成签名 url 来读取存储在谷歌云存储中的视频文件而无需下载它。

谷歌存储桶结构：

代码（已测试）：

import firebase_admin
from firebase_admin import credentials
from firebase_admin import storage
import datetime

import urllib.request as req
import cv2

cred = credentials.Certificate('Path\to\your\google-credential-file.json')
app = firebase_admin.initialize_app(cred, {'storageBucket': 'cnc-designs.appspot.com'}, name='storage')
bucket = storage.bucket(app=app)

def generate_image_url(blob_path):
    """ generate signed URL of a video stored on google storage. 
        Valid for 300 seconds in this case. You can increase this 
        time as per your requirement. 
    """                                                        
    blob = bucket.blob(blob_path) 
    return blob.generate_signed_url(datetime.timedelta(seconds=300), method='GET')


url = generate_image_url('sample1.mp4')
req.urlretrieve(url, "sample1.mp4")
cap = cv2.VideoCapture('sample1.mp4')

if cap.isOpened():
    print ("File Can be Opened")
    while(True):
        # Capture frame-by-frame
        ret, frame = cap.read()
        #print cap.isOpened(), ret
        if frame is not None:
            # Display the resulting frame
            cv2.imshow('frame',frame)
            # Press q to close the video windows before it ends if you want
            if cv2.waitKey(22) & 0xFF == ord('q'):
                break
        else:
            print("Frame is None")
            break
    # When everything done, release the capture
    cap.release()
    cv2.destroyAllWindows()
    print ("Video stop")
else:
    print("Not Working")

需要安装库：

firebase_admin : pip install firebase_admin

Answer 2

是的。 您需要使用 Google Storage 公共网址

cap = cv2.VideoCapture('https://storage.googleapis.com//your_Bucket//sample1.mp4')