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• Opencv VideoCapture not streaming RTSP link and returns "no frame!"

  6 September 2023, by Asadullah Naeem

  I am trying to stream my HikVision IP camera throough python. I am using cv2.VideoCapture("rtsp_link") which works fine on my Laptop but when I try to run the same python script with same Opencv and FFmpeg version it gives me following error:

  


  Error:

  


  [h264 @ 000002124c7f9a40] missing picture in access unit with size 47
[h264 @ 000002124c7f9a40] no frame!


  


  I have so far tried to run this script on 5 computer devices but it gives the same error. I am using the following python script and my Opencv version is 4.6.0.66 and ffmpeg version 2022-06-20-git-56419428a8-essentials_build-www.gyan.dev:

  


  Python Script:

  


  import cv2

# RTSP stream URL
rtsp_url = "rtsp://username:password@ip_address:port/Streaming/Channels/501"

# Open the RTSP stream
cap = cv2.VideoCapture(rtsp_url)

# Check if the stream was successfully opened
if not cap.isOpened():
    print("Failed to open RTSP stream.")
    exit()

# Read and display frames from the stream
while True:
    # Read a frame from the stream
    ret, frame = cap.read()

    # Check if the frame was successfully read
    if not ret:
        print("Failed to read frame from RTSP stream.")
        break

    # Display the frame
    cv2.imshow("RTSP Stream", frame)

    # Exit if 'q' is pressed
    if cv2.waitKey(1) & 0xFF == ord('q'):
        break

# Release the resources
cap.release()
cv2.destroyAllWindows()



  


  Update:

  


  Code runs on a laptop on both wifi and mobile internet (4G) but on other devices rtsp link is accessible only with mobile internet (4G).

  


• Black overlay appears when merging a transparent video to another video

  13 June 2012, by RakeshS

  This is what I have done so far:

  Command to create a transparent PNG image:

  convert -size 640x480 -background transparent -fill blue \
  
  -gravity South label:ROCK image1-0.png

  Command to create a transparent video:

  ffmpeg -loop 1 -f image2 -i image1-0.png -r 20 -vframes 100 \
  
  -vcodec png -pix_fmt bgra mov-1.mov

  (as per this post) - I expect this video to be a transparent video.

  Command to overlay a video with another:

  ffmpeg -i final-video.mov -sameq -ar 44100 \
  
  -vf "movie=mov-1.mov [logo];[in][logo] overlay=0:0 [out]" \
  
  -strict experimental final-video.mov

  Above commands works perfect and I have not faced any problem, but I don't get what I expect which is kinda watermarking effect, I want mov-1.mov to be transparent with final-video.mov.

  Questions:

  1. Is there any way to verify if the generated video is transparent? other than merging?
  2. Not sure why the above mov-1.mov is not transparent when it is merged with final-video.mov, any info to solve this problem would be great.

  Please help.

• Error with LocalAudioFile(file) returns OSError: [Errno 2] No such file or directory

  5 March 2016, by beriukay

  Much like the question here http://developer.echonest.com/forums/thread/3843#reply, I am having the following error:

  File
  "/usr/local/lib/python2.7/dist-packages/echonest/remix/audio.py", line
  944, in init
  sampleRate=sampleRate, numChannels=numChannels) File "/usr/local/lib/python2.7/dist-packages/echonest/remix/audio.py", line
  403, in init
  self.load() File "/usr/local/lib/python2.7/dist-packages/echonest/remix/audio.py", line
  421, in load
  numChannels=self.numChannels, sampleRate=self.sampleRate, verbose=self.verbose) File
  "/usr/local/lib/python2.7/dist-packages/echonest/remix/support/ffmpeg.py",
  line 91, in ffmpeg
  close_fds=(not win) File "/usr/lib/python2.7/subprocess.py", line 710, in init
  errread, errwrite) File "/usr/lib/python2.7/subprocess.py", line 1327, in _execute_child
  raise child_exception OSError: [Errno 2] No such file or directory

  I checked input and output file permissions, made sure that both files and all related file paths existed, and that I have all the relevant python tools installed. The first clue is that Subprocess.py is having trouble. Looking at ffmpeg.py on line 88, I started playing around with the Popen function call to see how and why it was misbehaving.

  Solution:

  After messing around with the ffmpeg.py file, I piped the input to the shell (shell=True instead of shell=False), which raised the following error:

  check raise Run timeError(ffmpeg_install_instructions) RuntimeError: en-ffmpeg not found! Please make sure ffmpeg is installed and create a link as follows: sudo ln -s which ffmpeg /usr/local/bin/en-ffmpeg Alternatively, import echonest.remix.support.ffmpeg and modify ffmpeg.FFMPEG to name the appropriate binary.

  So, to finalize the solution, you need to get the binary from https://ffmpeg.org/download.html#build-linux, which in Ubuntu 14.04 means you just need to:

  sudo add-apt-repository ppa:mc3man/trusty-media
  
  sudo apt-get update && sudo apt-get upgrade
  
  sudo apt-get install ffmpeg
  
  sudo ln -s `which ffmpeg` /usr/local/bin/en-ffmpeg

  That should clear this problem right up.