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• Creating an MP4 video with ffmpeg from timestamped JPEG frames received by pipe

  16 août 2024, par Denis Fevralev

  I need to create a video with following conditions :

  


  

  1. It can only be made from a sequence of JPEG files, each having its timestamp (milliseconds) in the name. The images' durations are not the same, they differ, so i cannot just concat them all and use particular fps

  


  2. There are several tar archives with the images sequences, the archives are kind of huge so I read them from a file storage as an async steam of data and cannot save them on the disk as files. The frames are read and right away put to ffmpeg running process stdin.

  


  3. The images may have different aspect ratios so it's required to make a NxN square and scale the images to fit in with filling the empty space with pads

  


  


  My current solution :

  


  ffmpeg -r $someFpsValue -i - -vf scale=w=$w:h=$h:force_original_aspect_ratio=1,pad=$w:$h:(((ow-iw)/2)):(((oh-ih)/2)) result.mp4


  


  As you can see, it doesn't let me concat the images with correct durations. I know that the concat demuxer can solve the problem of merging images with different durations but seemingly it doesn't work with pipe protocol. I have an idea of evaluating an average fps as (videoFramesCount) / (videoDurationInSeconds) for -r argument, or maybe even counting the fps for each video's second and then getting the avg, but maybe there is a more reliable solution (like some concat demuxer analogue) ?

  


  Thanks in advance :)

  


• How can i convert and compress in real time batch of images to mp4 video file ?

  29 juin 2015, par Brubaker Haim

  In my directory on the hard disk i have many images : screenshot000001.bmp , screenshot000002.bmp....screenshot001200.bmp

  I want to do two things :

  1. For testing using the cmd(Command Prompt) and to compress and convert the images to mp4 video file.

  2. In my program in real time while my program take the screenshots and save them to the hard disk to compress them and build the mp4 video file in real time.

  For the first part i tried to type in cmd :

  ffmpeg -f image2 -i screenshot%d.bmp -vcodec libx264 -b 800k video.avi

  But what i got is two errors :

  [image2 @ 0000000004766380] Could find no file with path ’screenshot%d.bmp’ and
  index in the range 0-4
  screenshot%d.bmp : No such file or directory

  I copied the ffmpeg.exe to the directory where the images are in.
  E :\screenshots

  For the second part this how i’m taking the screenshots in real time :

  A button click event that start a timer :

  private void button1_Click(object sender, EventArgs e)
  
          {
  
              timer1.Start();
  
          }

  Then in the tick event :

      ScreenShot shot = new ScreenShot();
  
      public static int counter = 0;
  
      private void timer1_Tick(object sender, EventArgs e)
  
      {
  
          counter++;
  
          shot.GetScreenShot(@"e:\screenshots\", "screenshot");
  
          if (counter == 1200)
  
          {
  
              timer1.Stop();
  
          }
  
      }

  This line shot.GetScreenShot(@"e :\screenshots\", "screenshot") ; save the screenshots to the hard disk.
  Here after each screenshot save i want to compress and build the mp4 video file in real time.

  I tried this and got errors :

  ffmpeg -f image2 -i screenshot%06d.bmp -vcodec libx264 -b 800k video.avi

  Error message :

  ffmpeg version N-73165-gf1e1730 Copyright (
  
    built with gcc 4.9.2 (GCC)
  
    configuration: --enable-gpl --enable-vers
  
  isynth --enable-bzlib --enable-fontconfig -
  
  le-iconv --enable-libass --enable-libbluray
  
  enable-libdcadec --enable-libfreetype --ena
  
  ibilbc --enable-libmodplug --enable-libmp3l
  
  le-libopencore-amrwb --enable-libopenjpeg -
  
  able-libschroedinger --enable-libsoxr --ena
  
  ble-libtwolame --enable-libvidstab --enable
  
   --enable-libvorbis --enable-libvpx --enabl
  
  e-libx264 --enable-libx265 --enable-libxavs
  
  ble-decklink --enable-zlib
  
    libavutil      54. 27.100 / 54. 27.100
  
    libavcodec     56. 45.100 / 56. 45.100
  
    libavformat    56. 38.102 / 56. 38.102
  
    libavdevice    56.  4.100 / 56.  4.100
  
    libavfilter     5. 18.100 /  5. 18.100
  
    libswscale      3.  1.101 /  3.  1.101
  
    libswresample   1.  2.100 /  1.  2.100
  
    libpostproc    53.  3.100 / 53.  3.100
  
  [bmp @ 0000000002f77ce0] bad magic number
  
      Last message repeated 3 times
  
  [image2 @ 0000000002f76380] decoding for st
  
  [image2 @ 0000000002f76380] Could not find
  
   bmp, none): unspecified size
  
  Consider increasing the value for the 'anal
  
  screenshot%06d.bmp: could not find codec pa
  
  Input #0, image2, from 'screenshot%06d.bmp'
  
    Duration: 00:00:02.88, start: 0.000000, b
  
      Stream #0:0: Video: bmp, none, 25 fps,
  
  Please use -b:a or -b:v, -b is ambiguous
  
  Codec AVOption b (set bitrate (in bits/s))
  
  vi) has not been used for any stream. The m
  
  e (e.g. a video option with no video stream
  
  some encoder which was not actually used fo
  
  Output #0, avi, to 'video.avi':
  
  Output file #0 does not contain any stream

• Anomalie #3338 (Nouveau) : Problème de virgule dans les CSS générées

  10 novembre 2014, par Julien Lusson

  Bonjour,

  Avec une installation SPIP 3.0.17 "fraiche" sans personnalisation, j’ai un soucis lors du calcul des CSS de l’espace privé, les valeurs décimales ont une virgule comme séparateur à la place du point, ce qui rend invalide les propriétés en question.

  Exemple pour le code suivant (style_prive.css) :
  

  #haut h1,h1.grostitre margin-top :[(#ENVmargin-bottom|mult1.5|div2|div#GETline-height)em]
  

  
  Donne :
  

  #haut h1,h1.grostitre margin-top:0,75em
  

  La raison : le serveur est configuré en locale française (fr_FR.UTF-8), si j’indique à PHP d’utiliser la locale US (intl.default_locale = en_US.UTF-8), je retrouve le point dans les CSS.

  Une solution de résolution au niveau de spip serait de définir la locale globalement via setlocale(LC_ALL, ’en_US.UTF-8’) ou uniquement pour les fichiers CSS.