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• ffmpeg doesn't work when the script is launched by cron - No protocol specified, Cannot open display :0.0

  14 janvier 2024, par a k

  ffmpeg in my script doesn't work when the script is launched by cron of the root

  


  Error : No protocol specified, Cannot open display :0.0

  


  OS : Ubuntu 20.04

  


  #!/bin/bash
log=/var/log/log2/log2.txt

echo ______________ $(date) >> "$log"
echo "$""DISPLAY" "=      "  "$DISPLAY" >> "$log" ;
echo whoami '         ' $(whoami) >> "$log" 
echo pwd '            ' $(pwd) >> "$log" 
echo "$""USER" "=" '        ' "$USER" >> "$log"
echo PATH '           ' "$PATH" >> "$log"
echo which ffmpeg '   ' $(which ffmpeg)>> "$log" 
echo whereis ffmpeg ' ' $(whereis ffmpeg) >> "$log" 
echo "\nls -l /bin/* | grep ffmpeg" '        ' >> "$log"
ls -l /usr/bin/* | grep ffmpeg >> "$log"
echo "ls -l /var/log | grep log2" ' '>> "$log"
ls -l /var/log | grep log2 >> "$log"

ffmpeg -y -f x11grab -s 1366x768 -i :0.0 -r 25 /var/log/log2/test.mp4 -loglevel error 2>>"$log" &

echo "pid ffmpeg ""$""!"" = " "$!" >> "$log" 
sleep 5
kill "$!"
echo exit >> "$log"
exit


  


  When Cron (Cron of the root) launches the script, ffmpeg shows the error "No protocol specified, Cannot open display :0.0"

  


  /var/log/log2/log2.txt :

  


  ______________ ven. 05 mai 2023 04:10:01 CEST
$DISPLAY =       
whoami           root
pwd              /root
$USER =          
PATH             /usr/bin:/bin
which ffmpeg     /usr/bin/ffmpeg
whereis ffmpeg   ffmpeg: /usr/bin/ffmpeg /usr/share/ffmpeg /usr/share/man/man1/ffmpeg.1.gz
ls -l /usr/bin/* | grep ffmpeg  
-rwxr-xr-x 1 root   root      284976 mai   18  2022 /usr/bin/ffmpeg
ls -l /var/log | grep log2  
drwxrwxrwx  2 root              root               4096 mai    5 04:09 log2
pid ffmpeg $! =  74590
No protocol specified
[x11grab @ 0x56244aa06740] Cannot open display :0.0, error 1.
:0.0: Input/output error
exit


  


  When I launch the script manually as a not-root user (with sudo), everything work correctly :

  


  ______________ ven. 05 mai 2023 04:10:47 CEST
$DISPLAY =       :0
whoami           root
pwd              /home/an
$USER =          root
PATH             /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/snap/bin
which ffmpeg     /usr/bin/ffmpeg
whereis ffmpeg   ffmpeg: /usr/bin/ffmpeg /usr/share/ffmpeg /usr/share/man/man1/ffmpeg.1.gz
ls -l /usr/bin/* | grep ffmpeg  
-rwxr-xr-x 1 root   root      284976 mai   18  2022 /usr/bin/ffmpeg
ls -l /var/log | grep log2  
drwxrwxrwx  2 root              root               4096 mai    5 04:09 log2
pid ffmpeg $! =  74618
exit


  


  When I launch the script manually as the root, everything works correctly :

  


  ______________ ven. 05 mai 2023 04:11:27 CEST
$DISPLAY =       :0
whoami           root
pwd              /root
$USER =          root
PATH             /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/snap/bin
which ffmpeg     /usr/bin/ffmpeg
whereis ffmpeg   ffmpeg: /usr/bin/ffmpeg /usr/share/ffmpeg /usr/share/man/man1/ffmpeg.1.gz
ls -l /usr/bin/* | grep ffmpeg  
-rwxr-xr-x 1 root   root      284976 mai   18  2022 /usr/bin/ffmpeg
ls -l /var/log | grep log2  
drwxrwxrwx  2 root              root               4096 mai    5 04:11 log2
pid ffmpeg $! =  74683
exit


  


  When crontab of an ordinary user launches the script, it works correctly :

  


  $DISPLAY =       
whoami           an
pwd              /home/an
$USER =          
PATH             /usr/bin:/bin
which ffmpeg     /usr/bin/ffmpeg
whereis ffmpeg   ffmpeg: /usr/bin/ffmpeg /usr/share/ffmpeg /usr/share/man/man1/ffmpeg.1.gz
ls -l /usr/bin/* | grep ffmpeg  
-rwxr-xr-x 1 root   root      284976 mai   18  2022 /usr/bin/ffmpeg
ls -l /var/log | grep log2  
drwxrwxrwx  2 root              root               4096 mai    5 05:05 log2
pid ffmpeg $! =  77601
exit


  


  I have tried to put into the script :

  


  export DISPLAY=":0"

  


  export DISPLAY=":0.0"

  


  export DISPLAY=":1"

  


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

  6 septembre 2023, par 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).

  


• How to resize an animated webp？

  23 mai 2023, par shsf

  I want to be able to change the size of a dynamic webp.
Sample picture address : https://postimg.cc/2qpx5bQm
I found this website to do just that : https://ezgif.com/resize

  


  So how can I implement something similar in my own program ?
I tried using ImageMagick7 or ffmpeg5, but failed.

  


  environment :

  


  [developer@Dev_Payment_229 ~]$ cat /etc/redhat-release

  


  CentOS Linux release 7.8.2003 (Core)

  


  1. tried ffmpeg :

  


  [developer@Dev_Payment_229 ~]$ /opt/ffmpeg-5/ffmpeg -i b.webp -vf "scale=320:-1" b_320.webp
ffmpeg version 5.1.1-static https://johnvansickle.com/ffmpeg/  Copyright (c) 2000-2022 the FFmpeg developers
  built with gcc 8 (Debian 8.3.0-6)
  configuration: --enable-gpl --enable-version3 --enable-static --disable-debug --disable-ffplay --disable-indev=sndio --disable-outdev=sndio --cc=gcc --enable-fontconfig --enable-frei0r --enable-gnutls --enable-gmp --enable-libgme --enable-gray --enable-libaom --enable-libfribidi --enable-libass --enable-libvmaf --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-librubberband --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libvorbis --enable-libopus --enable-libtheora --enable-libvidstab --enable-libvo-amrwbenc --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libdav1d --enable-libxvid --enable-libzvbi --enable-libzimg
  libavutil      57. 28.100 / 57. 28.100
  libavcodec     59. 37.100 / 59. 37.100
  libavformat    59. 27.100 / 59. 27.100
  libavdevice    59.  7.100 / 59.  7.100
  libavfilter     8. 44.100 /  8. 44.100
  libswscale      6.  7.100 /  6.  7.100
  libswresample   4.  7.100 /  4.  7.100
  libpostproc    56.  6.100 / 56.  6.100
[webp @ 0x7686f40] skipping unsupported chunk: ANIM
[webp @ 0x7686f40] skipping unsupported chunk: ANMF
    Last message repeated 10 times
[webp @ 0x7686f40] image data not found
[webp_pipe @ 0x7685700] Could not find codec parameters for stream 0 (Video: webp, none): unspecified size
Consider increasing the value for the 'analyzeduration' (0) and 'probesize' (5000000) options
Input #0, webp_pipe, from 'b.webp':
  Duration: N/A, bitrate: N/A
  Stream #0:0: Video: webp, none, 25 fps, 25 tbr, 25 tbn
Stream mapping:
  Stream #0:0 -> #0:0 (webp (native) -> webp (libwebp_anim))
Press [q] to stop, [?] for help
[webp @ 0x7697600] skipping unsupported chunk: ANIM
[webp @ 0x7697600] skipping unsupported chunk: ANMF
    Last message repeated 10 times
[webp @ 0x7697600] image data not found
Error while decoding stream #0:0: Invalid data found when processing input
Cannot determine format of input stream 0:0 after EOF
Error marking filters as finished
Conversion failed!


  


  It seems that ffmpeg cannot recognize this dynamic webp image.

  


  2. tried ImageMagick7

  


  install :

  


   yum -y install libwebp-devel libwebp-tools
[root@Dev_FTP_241 developer]# yum list installed | grep webp
libwebp.x86_64                         0.3.0-11.el7               @updates
libwebp-devel.x86_64                   0.3.0-11.el7               @updates
libwebp-tools.x86_64                   0.3.0-11.el7               @updates



  


  source code: https://github.com/ImageMagick/ImageMagick/archive/refs/tags/7.1.1-0.tar.gz
tar -xvf ImageMagick-7.1.1-0.tar.gz
./configure --with-webp --prefix=/usr/local/imagemagick
make
make install


  


  single webp can be resized :

  


  [root@Dev_FTP_241 developer]#  /usr/local/imagemagick/bin/convert -resize 480  simple.webp simple_480.webp
Decoded /tmp/magick-LNPdXgk2zDpiuU6Qv9CpDups3560EATh. Dimensions: 2160 x 608. Now saving...
Saved file /tmp/magick-Q8JHRZZOXdp1r1x187eftzsFlw8AqAuo


  


  but animated webp failed :

  


  [root@Dev_FTP_241 developer]#  /usr/local/imagemagick/bin/convert -resize 480  b.webp b_480.webp
Error! Decoding of an animated WebP file is not supported.
       Use webpmux to extract the individual frames or
       vwebp to view this image.
Decoding of /tmp/magick-jMiy7ytmAnBzpS8UpafCQ5B44BjDTUSD failed.
Status: 4 (UNSUPPORTED_FEATURE)
convert: delegate failed `'dwebp' -pam '%i' -o '%o'' @ error/delegate.c/InvokeDelegate/1924.
convert: unable to open file '/tmp/magick-D-NMEGWU_a0IypZWwTpYiWIE61nteoig': No such file or directory @ error/constitute.c/ReadImage/786.
convert: no images defined `b_480.webp' @ error/convert.c/ConvertImageCommand/3342.