Port missing in uri warning: Error opening http URL with Python cv2.VideoCapture() on Jetson

Robotics & Edge Computing Jetson & Embedded Systems Jetson AGX Xavier
1

I’m trying to connect a Axis network camera with Jetson xavier using cv2.VideoCapture() , but I get the following error and cannot connect.

How can I get connected?
On my other Ubuntu PC, I was able to connect with the same program.

[tcp @ 0x28bb6cd0] Port missing in uri
[ WARN:0] global /home/nvidia/host/build_opencv/nv_opencv/modules/videoio/src/cap_gstreamer.cpp (1757) handleMessage OpenCV | GStreamer warning: Embedded video playback halted; module source reported: Could not resolve server name.
[ WARN:0] global /home/nvidia/host/build_opencv/nv_opencv/modules/videoio/src/cap_gstreamer.cpp (886) open OpenCV | GStreamer warning: unable to start pipeline
[ WARN:0] global /home/nvidia/host/build_opencv/nv_opencv/modules/videoio/src/cap_gstreamer.cpp (480) isPipelinePlaying OpenCV | GStreamer warning: GStreamer: pipeline have not been created

The program is as follows:

from threading import Thread
import cv2
import time

class VideoScreenshot(object):

def __init__(self, src=0):

    self.capture = cv2.VideoCapture(src)

    # Take screenshot every x seconds
    self.screenshot_interval = 1

    # Default resolutions of the frame are obtained (system dependent)
    self.frame_width = int(self.capture.get(3))
    self.frame_height = int(self.capture.get(4))

    # Start the thread to read frames from the video stream
    self.thread = Thread(target=self.update, args=())
    self.thread.daemon = True
    self.thread.start()

def update(self):
    # Read the next frame from the stream in a different thread
    while True:
        if self.capture.isOpened():
            (self.status, self.frame) = self.capture.read()

def show_frame(self):
    # Display frames in main program
    
    if self.status:
        cv2.imshow('frame', self.frame)
    
    # Press Q on keyboard to stop recording
    key = cv2.waitKey(1)
    if key == ord('q'):
        self.capture.release()
        cv2.destroyAllWindows()
        exit(1)

if name == ‘main’:

stream_link = 'http://root:password@192.xxx.x.xx/mjpg/1/video.mjpg?resolution=1920x1080'
video_stream_widget = VideoScreenshot(stream_link)

while True:
    try:
        video_stream_widget.show_frame()
    except AttributeError:
        pass

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Also, when the stream link is rtsp, it connects to the camera, but there is a huge delay, so I would like to use htttp.

3

Hi,
Not sure if http link works in cv2.VideoCapture(). This would need other users to share experience.

We suggest try RTSP in gst-launch-1.0 command like:

$ gst-launch-1.0 uridecodebin uri=rtsp://_URI_OF_THE_SOURCE_ ! nvoverlaysink

If above command works, please apply the URI to this python sample and give it a try:
Doesn't work nvv4l2decoder for decoding RTSP in gstreamer + opencv - #3 by DaneLLL

4

Thanks for the reply.

I’ve tried rtsp before and confirmed that it connects, but I want to use http because of the high latency.

On my other PC, I was able to connect using http, so what is different about jetson?

In addition, is there any other way to connect to a network camera in python other than cv2.VideoCapture()?

5

Hi,
You may check if you can construct a gstreamer pipeline for http protocol. Not sure but may be able to utilize this plugin: souphttpsrc

We don’t have much experience in receiving http stream. You may go to gstreamer forum to get further assistance. Once you get a working pipeline with software decoder such as avdec_h264, you can replace it with nvv4l2decoder to enable hardware decoding.

6

You can use two ways from opencv. With ffmpeg or gstreamer. The latter is by far the easiest on jetson to get good performance. This works for me:

cap = cv2.VideoCapture("uridecodebin uri=http://192.168.0.40:8080/playlist.m3u8 ! nvvidconv ! video/x-raw,format=BGRx ! videoconvert ! video/x-raw,format=BGR ! appsink drop=1", cv::CAP_GSTREAMER);

With ffmpeg capture backend, in my case it works with C++

  setenv ("OPENCV_FFMPEG_CAPTURE_OPTIONS", "protocol_whitelist;tcp,http", 1);
  cap->open("http://192.168.0.40:8080/playlist.m3u8", cv::CAP_FFMPEG);

but python crashes with:

import os
os.environ["OPENCV_FFMPEG_CAPTURE_OPTIONS"] = "protocol_whitelist;tcp,http;1"
cap = cv2.VideoCapture("http://192.168.0.40:8080/playlist.m3u8", cv2.CAP_FFMPEG)

Anyway, you would need an opencv build configured for a FFMPEG version having HW acceleration and this is not trivial.

Try gstreamer pipeline with uridecodebin.