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• ffmpeg when asked to map a .mov file's streams 0,1,3 actually maps streams 0,1,2

  15 septembre 2023, par user2258729

  I'm trying the following :

  


  Start with in.mov which has 4 streams 0:0 - 0:3.

  


  Audio, Video, Data (unknown), and mJpeg.

  


  Trying to map 0:0, 0:1, and 0:3 into out013.mov.

  


  ffmpeg -i in.mov -map 0 -map -0:2 -c copy out013.mov

  


  or

  


  ffmpeg -i in.mov -map 0:0 -map 0:1 -map 0:2 -c copy out013.mov

  


  ffmpeg tells me that 3 streams are mapped :

  


    Stream #0:0 -> #0:0 (copy)
  Stream #0:1 -> #0:1 (copy)
  Stream #0:3 -> #0:2 (copy)


  


  ffprobe disagrees. According to it what really happened was :

  


    Stream #0:0 -> #0:0 (copy)
  Stream #0:1 -> #0:1 (copy)
  Stream #0:2 -> #0:2 (copy)


  


  "Who needs a thumbnail image anyways, screw it !" I said. "Let's just get rid of the data."

  


  ffmpeg -i out013.mov -map 0:0 -map 0:1 -c copy out01.mov

  


  ffmpeg tells me that 2 streams are mapped :

  


    Stream #0:0 -> #0:0 (copy)
  Stream #0:1 -> #0:1 (copy)


  


  ffprobe disagrees. According to it what really happened was :

  


    Stream #0:0 -> #0:0 (copy)
  Stream #0:1 -> #0:1 (copy)
  Stream #0:2 -> #0:2 (copy)


  


  Seems like I can't rid myself of that data stream (0:2).

  


  Below is the output from the ffprobe and ffmpeg for the first scenario.

  


  Any ideas ?

  


  ---

  


  ffprobe in.mov

  


  ffprobe version 2023-09-07-git-9c9f48e7f2-essentials_build-www.gyan.dev Copyright (c) 2007-2023 the FFmpeg developers
  built with gcc 12.2.0 (Rev10, Built by MSYS2 project)
  configuration: --enable-gpl --enable-version3 --enable-static --disable-w32threads --disable-autodetect --enable-fontconfig --enable-iconv --enable-gnutls --enable-libxml2 --enable-gmp --enable-bzlib --enable-lzma --enable-zlib --enable-libsrt --enable-libssh --enable-libzmq --enable-avisynth --enable-sdl2 --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxvid --enable-libaom --enable-libopenjpeg --enable-libvpx --enable-mediafoundation --enable-libass --enable-libfreetype --enable-libfribidi --enable-libharfbuzz --enable-libvidstab --enable-libvmaf --enable-libzimg --enable-amf --enable-cuda-llvm --enable-cuvid --enable-ffnvcodec --enable-nvdec --enable-nvenc --enable-dxva2 --enable-d3d11va --enable-libvpl --enable-libgme --enable-libopenmpt --enable-libopencore-amrwb --enable-libmp3lame --enable-libtheora --enable-libvo-amrwbenc --enable-libgsm --enable-libopencore-amrnb --enable-libopus --enable-libspeex --enable-libvorbis --enable-librubberband
  libavutil      58. 19.100 / 58. 19.100
  libavcodec     60. 26.100 / 60. 26.100
  libavformat    60. 11.100 / 60. 11.100
  libavdevice    60.  2.101 / 60.  2.101
  libavfilter     9. 11.100 /  9. 11.100
  libswscale      7.  3.100 /  7.  3.100
  libswresample   4. 11.100 /  4. 11.100
  libpostproc    57.  2.100 / 57.  2.100
[mov,mp4,m4a,3gp,3g2,mj2 @ 0000023b088f3300] stream 0, timescale not set
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'in.mov':
  Metadata:
    major_brand     : qt
    minor_version   : 0
    compatible_brands: qt
    creation_time   : 2023-08-22T21:23:09.000000Z
    title           : Redacted
    com.apple.quicktime.displayname: Redacted
    com.apple.quicktime.title: Redacted
  Duration: 00:00:30.03, start: 0.000000, bitrate: 152583 kb/s
  Stream #0:0[0x1](eng): Audio: pcm_s24le (lpcm / 0x6D63706C), 48000 Hz, 2 channels, s32 (24 bit), 2304 kb/s (default)
    Metadata:
      creation_time   : 2023-08-22T21:23:09.000000Z
      handler_name    : Core Media Audio
      vendor_id       : [0][0][0][0]
  Stream #0:1[0x2](und): Video: prores (Standard) (apcn / 0x6E637061), yuv422p10le(bt709, progressive), 1920x1080, 150213 kb/s, SAR 1:1 DAR 16:9, 29.97 fps, 29.97 tbr, 30k tbn (default)
    Metadata:
      creation_time   : 2023-08-22T21:23:09.000000Z
      handler_name    : Core Media Video
      vendor_id       : [0][0][0][0]
      encoder         : Apple ProRes 422
      timecode        : 00:00:00:00
  Stream #0:2[0x3](und): Data: none (tmcd / 0x64636D74), 0 kb/s (default)
    Metadata:
      creation_time   : 2023-08-22T21:23:09.000000Z
      handler_name    : Core Media Time Code
      timecode        : 00:00:00:00
  Stream #0:3[0x0]: Video: mjpeg (Progressive), yuvj420p(pc, bt470bg/unknown/unknown), 1920x1080 [SAR 72:72 DAR 16:9], 90k tbr, 90k tbn (attached pic)
Unsupported codec with id 0 for input stream 2


  


  ---

  


  ffmpeg -i in.mov -map 0:0 -map 0:1 -map 0:3 -c copy out013.mov

  


  ffmpeg version 2023-09-07-git-9c9f48e7f2-essentials_build-www.gyan.dev Copyright (c) 2000-2023 the FFmpeg developers
  built with gcc 12.2.0 (Rev10, Built by MSYS2 project)
  configuration: --enable-gpl --enable-version3 --enable-static --disable-w32threads --disable-autodetect --enable-fontconfig --enable-iconv --enable-gnutls --enable-libxml2 --enable-gmp --enable-bzlib --enable-lzma --enable-zlib --enable-libsrt --enable-libssh --enable-libzmq --enable-avisynth --enable-sdl2 --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxvid --enable-libaom --enable-libopenjpeg --enable-libvpx --enable-mediafoundation --enable-libass --enable-libfreetype --enable-libfribidi --enable-libharfbuzz --enable-libvidstab --enable-libvmaf --enable-libzimg --enable-amf --enable-cuda-llvm --enable-cuvid --enable-ffnvcodec --enable-nvdec --enable-nvenc --enable-dxva2 --enable-d3d11va --enable-libvpl --enable-libgme --enable-libopenmpt --enable-libopencore-amrwb --enable-libmp3lame --enable-libtheora --enable-libvo-amrwbenc --enable-libgsm --enable-libopencore-amrnb --enable-libopus --enable-libspeex --enable-libvorbis --enable-librubberband
  libavutil      58. 19.100 / 58. 19.100
  libavcodec     60. 26.100 / 60. 26.100
  libavformat    60. 11.100 / 60. 11.100
  libavdevice    60.  2.101 / 60.  2.101
  libavfilter     9. 11.100 /  9. 11.100
  libswscale      7.  3.100 /  7.  3.100
  libswresample   4. 11.100 /  4. 11.100
  libpostproc    57.  2.100 / 57.  2.100
[mov,mp4,m4a,3gp,3g2,mj2 @ 000001f92e383880] stream 0, timescale not set
[aist#0:0/pcm_s24le @ 000001f92e50f400] Guessed Channel Layout: stereo
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'in.mov':
  Metadata:
    major_brand     : qt
    minor_version   : 0
    compatible_brands: qt
    creation_time   : 2023-08-22T21:23:09.000000Z
    title           : Redacted
    com.apple.quicktime.displayname: Redacted
    com.apple.quicktime.title: Redacted
  Duration: 00:00:30.03, start: 0.000000, bitrate: 152583 kb/s
  Stream #0:0[0x1](eng): Audio: pcm_s24le (lpcm / 0x6D63706C), 48000 Hz, 2 channels, s32 (24 bit), 2304 kb/s (default)
    Metadata:
      creation_time   : 2023-08-22T21:23:09.000000Z
      handler_name    : Core Media Audio
      vendor_id       : [0][0][0][0]
  Stream #0:1[0x2](und): Video: prores (Standard) (apcn / 0x6E637061), yuv422p10le(bt709, progressive), 1920x1080, 150213 kb/s, SAR 1:1 DAR 16:9, 29.97 fps, 29.97 tbr, 30k tbn (default)
    Metadata:
      creation_time   : 2023-08-22T21:23:09.000000Z
      handler_name    : Core Media Video
      vendor_id       : [0][0][0][0]
      encoder         : Apple ProRes 422
      timecode        : 00:00:00:00
  Stream #0:2[0x3](und): Data: none (tmcd / 0x64636D74), 0 kb/s (default)
    Metadata:
      creation_time   : 2023-08-22T21:23:09.000000Z
      handler_name    : Core Media Time Code
      timecode        : 00:00:00:00
  Stream #0:3[0x0]: Video: mjpeg (Progressive), yuvj420p(pc, bt470bg/unknown/unknown), 1920x1080 [SAR 72:72 DAR 16:9], 90k tbr, 90k tbn (attached pic)
Output #0, mov, to 'out013.mov':
  Metadata:
    major_brand     : qt
    minor_version   : 0
    compatible_brands: qt
    com.apple.quicktime.title: Redacted
    title           : Redacted
    com.apple.quicktime.displayname: Redacted
    encoder         : Lavf60.11.100
  Stream #0:0(eng): Audio: pcm_s24le (in24 / 0x34326E69), 48000 Hz, stereo, s32 (24 bit), 2304 kb/s (default)
    Metadata:
      creation_time   : 2023-08-22T21:23:09.000000Z
      handler_name    : Core Media Audio
      vendor_id       : [0][0][0][0]
  Stream #0:1(und): Video: prores (Standard) (apcn / 0x6E637061), yuv422p10le(bt709, progressive), 1920x1080 [SAR 1:1 DAR 16:9], q=2-31, 150213 kb/s, 29.97 fps, 29.97 tbr, 30k tbn (default)
    Metadata:
      creation_time   : 2023-08-22T21:23:09.000000Z
      handler_name    : Core Media Video
      vendor_id       : [0][0][0][0]
      encoder         : Apple ProRes 422
      timecode        : 00:00:00:00
  Stream #0:2: Video: mjpeg (Progressive) (jpeg / 0x6765706A), yuvj420p(pc, bt470bg/unknown/unknown), 1920x1080 [SAR 72:72 DAR 16:9], q=2-31, 90k tbr, 90k tbn (attached pic)
Stream mapping:
  Stream #0:0 -> #0:0 (copy)
  Stream #0:1 -> #0:1 (copy)
  Stream #0:3 -> #0:2 (copy)
Press [q] to stop, [?] for help
[out#0/mov @ 000001f92e398340] video:550881kB audio:8446kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown
frame=  900 fps=0.0 q=-1.0 Lq=-1.0 size=  559116kB time=00:00:30.02 bitrate=152567.6kbits/s speed= 117x


  


  ---

  


  ffprobe out013.mov

  


  ffprobe version 2023-09-07-git-9c9f48e7f2-essentials_build-www.gyan.dev Copyright (c) 2007-2023 the FFmpeg developers
  built with gcc 12.2.0 (Rev10, Built by MSYS2 project)
  configuration: --enable-gpl --enable-version3 --enable-static --disable-w32threads --disable-autodetect --enable-fontconfig --enable-iconv --enable-gnutls --enable-libxml2 --enable-gmp --enable-bzlib --enable-lzma --enable-zlib --enable-libsrt --enable-libssh --enable-libzmq --enable-avisynth --enable-sdl2 --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxvid --enable-libaom --enable-libopenjpeg --enable-libvpx --enable-mediafoundation --enable-libass --enable-libfreetype --enable-libfribidi --enable-libharfbuzz --enable-libvidstab --enable-libvmaf --enable-libzimg --enable-amf --enable-cuda-llvm --enable-cuvid --enable-ffnvcodec --enable-nvdec --enable-nvenc --enable-dxva2 --enable-d3d11va --enable-libvpl --enable-libgme --enable-libopenmpt --enable-libopencore-amrwb --enable-libmp3lame --enable-libtheora --enable-libvo-amrwbenc --enable-libgsm --enable-libopencore-amrnb --enable-libopus --enable-libspeex --enable-libvorbis --enable-librubberband
  libavutil      58. 19.100 / 58. 19.100
  libavcodec     60. 26.100 / 60. 26.100
  libavformat    60. 11.100 / 60. 11.100
  libavdevice    60.  2.101 / 60.  2.101
  libavfilter     9. 11.100 /  9. 11.100
  libswscale      7.  3.100 /  7.  3.100
  libswresample   4. 11.100 /  4. 11.100
  libpostproc    57.  2.100 / 57.  2.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'out013.mov':
  Metadata:
    major_brand     : qt
    minor_version   : 512
    compatible_brands: qt
    title           : Redacted
    encoder         : Lavf60.11.100
    timecode        : 00:00:00:00
  Duration: 00:00:30.03, start: 0.000000, bitrate: 152523 kb/s
  Stream #0:0[0x1](eng): Audio: pcm_s24le (in24 / 0x34326E69), 48000 Hz, stereo, s32 (24 bit), 2304 kb/s (default)
    Metadata:
      handler_name    : Core Media Audio
      vendor_id       : [0][0][0][0]
  Stream #0:1[0x2]: Video: prores (Standard) (apcn / 0x6E637061), yuv422p10le(bt709, progressive), 1920x1080, 150213 kb/s, SAR 1:1 DAR 16:9, 29.97 fps, 29.97 tbr, 30k tbn (default)
    Metadata:
      handler_name    : Core Media Video
      vendor_id       : FFMP
      encoder         : Apple ProRes 422
      timecode        : 00:00:00:00
  Stream #0:2[0x4](eng): Data: none (tmcd / 0x64636D74), 0 kb/s
    Metadata:
      handler_name    : Core Media Video
      timecode        : 00:00:00:00
Unsupported codec with id 0 for input stream 2



  


• FFMPEG changes pixel values when reading and saving png without modification

  25 janvier 2023, par walrus

  This is a toy problem that is the result of my trying to identify a bug within a video pipeline I'm working on. The idea is that I want to take a frame from a YUV420 video, modify it as an RGB24 image, and reinsert it. To do this I convert YUV420 -> YUV444 -> RGB -> YUV444 -> YUV420. Doing this without any modification should result in the same frame however I noticed slight color transformations.

  


  I tried to isolate the problem using a toy 3x3 RGB32 png image. The function read_and_save_image reads the image and then saves it as new file. It returns the read pixel array. I run this function thrice successively using the output of the previous run as the input of the next. This is to demonstrate a perplexing fact. While passing an image through the function once causes the resulting image to have different pixel values, doing it twice does not change anything. Perhaps more confusing is that the pixel values returned by the function are all the same.

  


  tldr ; How can I load and save the toy image below using ffmpeg as a new file such that the pixel values of the new and original files are identical ?

  


  Here is the original image followed by the result from one and two passes through the function. Note that the pixel value displayed by when reading these images with Preview has changed ever so slightly. This becomes noticeable within a video.

  


  Test image (very small) ->&#xA; <-

  &#xA;

  Here are the pixel values read (note that after being loaded and saved there is a change) :

  &#xA;

  original test image

  &#xA;

  test image after one pass

  &#xA;

  test image after two passes

  &#xA;

  Edit : here is an RGB24 frame extracted from a video I am using to test my pipeline. I had the same issue with pixel values changing after loading and saving with ffmpeg.

  &#xA;

  frame from video I was testing pipeline on

  &#xA;

  Here is a screenshot showing how the image is noticeably darker after ffmpeg. Same pixels on the top right corner of the image.

  &#xA;

  

  &#xA;

  Here is the code of the toy problem :

  &#xA;

  import os
import ffmpeg
import numpy as np


def read_and_save_image(in_file, out_file, width, height, pix_fmt='rgb32'):
    input_data, _ = (
        ffmpeg
        .input(in_file)
        .output('pipe:', format='rawvideo', pix_fmt=pix_fmt)
        .run(capture_stdout=True)
    )
  
    frame = np.frombuffer(input_data, np.uint8)
    print(in_file,'\n', frame.reshape((height,width,-1)))
    
    save_data = (
        ffmpeg
            .input('pipe:', format='rawvideo', pix_fmt=pix_fmt, s='{}x{}'.format(width, height))
            .output(out_file, pix_fmt=pix_fmt)
            .overwrite_output()
            .run_async(pipe_stdin=True)
    )
    
    

    save_data.stdin.write(frame.tobytes())
    save_data.stdin.close()
    #save_data.wait()

    return frame

try:
    test_img = "test_image.png"
    test_img_1 = "test_image_1.png"
    test_img_2 = "test_image_2.png"
    test_img_3 = "test_image_3.png"

    width, height, pix_fmt = 3,3,'rgb32'
    #width, height, pix_fmt = video_stream['width'], video_stream['height'],  'rgb24'
    test_img_pxls = read_and_save_image(test_img,test_img_1, width, height, pix_fmt)
    test_img_1_pxls = read_and_save_image(test_img_1,test_img_2, width, height, pix_fmt)
    test_img_2_pxls = read_and_save_image(test_img_2,test_img_3, width, height, pix_fmt)

    print(np.array_equiv(test_img_pxls, test_img_1_pxls))
    print(np.array_equiv(test_img_1_pxls, test_img_2_pxls))

except ffmpeg.Error as e:
    print('stdout:', e.stdout.decode('utf8'))
    print('stderr:', e.stderr.decode('utf8'))
    raise e


!mediainfo --Output=JSON --Full $test_img
!mediainfo --Output=JSON --Full $test_img_1
!mediainfo --Output=JSON --Full $test_img_2


  &#xA;

  Here is the console output of the program that shows that the pixel arrays read by ffmpeg are the same despite the images being different.

  &#xA;

  test_image.png 
 [[[253 218 249 255]
  [252 213 248 255]
  [251 200 244 255]]

 [[253 227 250 255]
  [249 209 236 255]
  [243 169 206 255]]

 [[253 235 251 255]
  [245 195 211 255]
  [226 103 125 255]]]
test_image_1.png 
 [[[253 218 249 255]
  [252 213 248 255]
  [251 200 244 255]]

 [[253 227 250 255]
  [249 209 236 255]
  [243 169 206 255]]

 [[253 235 251 255]
  [245 195 211 255]
  [226 103 125 255]]]
test_image_2.png 
 [[[253 218 249 255]
  [252 213 248 255]
  [251 200 244 255]]

 [[253 227 250 255]
  [249 209 236 255]
  [243 169 206 255]]

 [[253 235 251 255]
  [245 195 211 255]
  [226 103 125 255]]]
True
True
{
"media": {
"@ref": "test_image.png",
"track": [
{
"@type": "General",
"ImageCount": "1",
"FileExtension": "png",
"Format": "PNG",
"FileSize": "4105",
"StreamSize": "0",
"File_Modified_Date": "UTC 2023-01-19 13:49:00",
"File_Modified_Date_Local": "2023-01-19 13:49:00"
},
{
"@type": "Image",
"Format": "PNG",
"Format_Compression": "LZ77",
"Width": "3",
"Height": "3",
"BitDepth": "32",
"Compression_Mode": "Lossless",
"StreamSize": "4105"
}
]
}
}

{
"media": {
"@ref": "test_image_1.png",
"track": [
{
"@type": "General",
"ImageCount": "1",
"FileExtension": "png",
"Format": "PNG",
"FileSize": "128",
"StreamSize": "0",
"File_Modified_Date": "UTC 2023-01-24 15:31:58",
"File_Modified_Date_Local": "2023-01-24 15:31:58"
},
{
"@type": "Image",
"Format": "PNG",
"Format_Compression": "LZ77",
"Width": "3",
"Height": "3",
"BitDepth": "32",
"Compression_Mode": "Lossless",
"StreamSize": "128"
}
]
}
}

{
"media": {
"@ref": "test_image_2.png",
"track": [
{
"@type": "General",
"ImageCount": "1",
"FileExtension": "png",
"Format": "PNG",
"FileSize": "128",
"StreamSize": "0",
"File_Modified_Date": "UTC 2023-01-24 15:31:59",
"File_Modified_Date_Local": "2023-01-24 15:31:59"
},
{
"@type": "Image",
"Format": "PNG",
"Format_Compression": "LZ77",
"Width": "3",
"Height": "3",
"BitDepth": "32",
"Compression_Mode": "Lossless",
"StreamSize": "128"
}
]
}
}



  &#xA;

• 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

  &#xA;

  Error : No protocol specified, Cannot open display :0.0

  &#xA;

  OS : Ubuntu 20.04

  &#xA;

  #!/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


  &#xA;

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

  &#xA;

  /var/log/log2/log2.txt :

  &#xA;

  ______________ 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


  &#xA;

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

  &#xA;

  ______________ 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


  &#xA;

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

  &#xA;

  ______________ 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


  &#xA;

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

  &#xA;

  $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


  &#xA;

  I have tried to put into the script :

  &#xA;

  export DISPLAY=":0"

  &#xA;

  export DISPLAY=":0.0"

  &#xA;

  export DISPLAY=":1"

  &#xA;