如何在python中使用opencv从sftp位置读取视频文件

Question

I am facing issue in reading file from sftp location using opencv lib. Can you tell me how to read file from sftp location or sftp file object. If can you tell me read large file directly to opencv lib then it's good things.

import paramiko
import cv2
import numpy as np

client = paramiko.SSHClient()
client.set_missing_host_key_policy(paramiko.AutoAddPolicy())
client.connect("IPADDRESS", port=22, username='USERNAME', password='PASSWORD')
t = client.get_transport()
sftp = paramiko.SFTPClient.from_transport(t)
sftp.chdir("/home/bizviz/devanshu_copy")

obj = sftp.open("SampleVideo_1280x720_1mb.mp4")

cap = cv2.VideoCapture.open(obj)

while True:
    _,frame = cap.read()
    print(frame)
    cv2.imshow('res', frame)
    key = cv2.waitKey(1)
    if key == 27:
        break

cap.release()
cv2.destroyAllWindows()

Answer 1

using just Paramiko you'll need to copy the file to the local filesystem and then use that local file for cv2.

cv2 doesn't accept this method of passing a file.

Of course, python has libraries for everything, so I think using fs.sshfs , which is an extension on pyfilesystem2 to include SFTP, should do the trick. NOTE HERE, this doesn't actually play nice with opencv-python .

---

EDIT1:

from the docs here you can see which ways you can pass a file to VideoCapture.Open().

Editing the code to copy the file locally and then pass the local file to openCV works correctly.

sftp.get('file.mp4', 'file.mp4')
sftp.close() # Also, close the sftp connection

cap = cv2.VideoCapture.open('file.mp4')

---

EDIT2:

So, mounting the SFTP filesystem to the local filesystem using ssfhs works. Best way would be to mount the SFTP on the OS level using the tested methods for this. Below is sample python code to do everything in python, but note that this assumes ssfhs can connect correctly to the SFTP host from commandline. I'm not explaining that part here as there are excellent different tutorials for that.

Note that this only contains some basic error checking so I advise to make sure you catch any errors that might pop up. This is proof of concept.

import cv2
import os
import subprocess


g_remoteuser = 'USERNAME'
g_remotepassword = 'PASSWORD'
g_remotehost = 'HOSTIP'
g_remotepath = '/home/{remoteuser}/files'.format(remoteuser=g_remoteuser)
g_localuser = 'LOCAL_MACHINE_LINUX_USERNAME'
g_localmntpath = '/home/{localuser}/mnt/remotehost/'.format(localuser=g_localuser)
g_filename = 'file.mp4'


def check_if_path_exists(path):
    # check if the path exists, create the path if it doesn't
    if not os.path.exists(path):
        os.makedirs(path)


def mount(remoteuser, remotehost, remotepath, remotepassword, localmntpath):
    check_if_path_exists(localmntpath)
    if not check_if_mounted(localmntpath):
        subprocess.call([
            '''echo "{remotepassword}" | sshfs {remoteuser}@{remotehost}:{remotepath} {localmntpath} \
             -o password_stdin -o UserKnownHostsFile=/dev/null -o StrictHostKeyChecking=no -o auto_unmount -o allow_other'''.format(
                remoteuser=remoteuser,
                remotehost=remotehost,
                remotepath=remotepath,
                localmntpath=localmntpath,
                remotepassword=remotepassword
            )], shell=True)


def unmount(path):
    try:
        subprocess.call(['sudo umount -l {path}'.format(path=path)], shell=True)
    except Exception as e:
        print(e)


def check_if_mounted(path):
    # check if there's actually files. Hacky way to check if the remote host is already mounted.
    # will of course fail if there's no files in the remotehost
    from os import walk
    f = []
    for (dirpath, dirnames, filenames) in walk(path):
        f.extend(filenames)
        f.extend(dirnames)
        if dirnames or filenames or f:
            return True
        break
    return False


if check_if_mounted(g_localmntpath):
    unmount(g_localmntpath)

mount(g_remoteuser, g_remotehost, g_remotepath, g_remotepassword, g_localmntpath)


cap = cv2.VideoCapture()
cap.open(g_localmntpath + g_filename)


while True:
    _, frame = cap.read()
    print(frame)
    cv2.imshow('res', frame)
    key = cv2.waitKey(1)
    if key == 27:
        break

cap.release()
cv2.destroyAllWindows()
unmount(g_localmntpath)