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• Unable to run ffmpeg with qProcess to extract a single frame from Vide

  24 janvier 2018, par user3840315

  I am trying to extract a single frame from a video using the QProcess in qt framework and ffmpeg and store it in a tmp folder. When I run the program in terminal command line it is able to extract it but not when QProcess runs it. I’m developing on a mac. What am I doing wrong.

  QString extractSingleFrame(QString videoPath, QDir tmpDir)
  
  {
  
      QString program = ffmpegPath();
  
      QProcess *ffmpegProcess = new QProcess();
  
      QString arguments;
  
      QFileInfo videoInfo(videoPath);
  
      QString videoName = videoInfo.fileName();
  
  
  
      QString firstFrameName(tmpDir.absolutePath() + "/" + videoName + ".jpg");
  
      arguments = " -y -i " + QDir::toNativeSeparators(videoPath)
  
                  + " -frames:v 1 -q:v 1 -f image2 " + QDir::toNativeSeparators(firstFrameName);
  
  
  
      QFile::remove(firstFrameName);
  
      qDebug() << "Starting program" << program + arguments;
  
      ffmpegProcess->start(program + arguments);
  
      // ffmpegProcess->start(program , QStringList() <<  arguments); this also doesnt work
  
      if (ffmpegProcess->state() == QProcess::Starting){
  
         qDebug() << "program is starting" + ffmpegProcess->state();
  
      }
  
      ffmpegProcess->waitForFinished(-1);
  
  
  
      qDebug() << "done";
  
  
  
      delete ffmpegProcess;
  
  
  
      return firstFrameName;
  
  }

  This is the printed command
  to start the program "ffmpeg -y -i "/Users/userX/test.mov" -vframes 1 -q:v 1 -f image2 "/var/folders/s1/vtv2cx36p3h0000gn/T/test-ywDBgj/test.mov.jpg""

• Anomalie #4363 : mot de passe vide bloque le formulaire de réinitialisation du mot de passe d’un u...

  3 août 2019, par b b

  Comme tu le dis, "on" ne veut pas, mais en attendant que quelqu’un propose mieux mette à disposition la super fonctionnalité "qu’on veut", on peut répondre à la demande avec ce bouton. C’est bien de rappeler qu’on fait de la merde et qu’on devrait s’améliorer, mais en attendant on peut toujours s’en sortir avec l’existant :*

• How to get native frame rate of vide with FFmpex ?

  18 juin 2021, par Flame_Phoenix

  Background

  


  I have an .mp4 video and I need to get the video's frame rate. Using ffmepg (in Linux) I know I can get this information via the following command :

  


  ffprobe -v 0 -of compact=p=0 -select_streams 0 -show_entries stream=r_frame_rate 'MyVideoFIle.mp4'


  


  Which returns :

  


  r_frame_rate=24000/1001


  


  FFmpex

  


  Doing this in bash is fine, but what I really want is to use it in my Elixir application. To this end I found out about ffmpex.

  


  First I tried using FFprobe :

  


  > FFprobe.format("Devil May Cry 5 Bury the Light LITTLE V COVER.mp4")

{:ok,
 %{
   "bit_rate" => "611784",
   "duration" => "482.999000",
   "filename" => "Devil May Cry 5 Bury the Light LITTLE V COVER.mp4",
   "format_long_name" => "QuickTime / MOV",
   "format_name" => "mov,mp4,m4a,3gp,3g2,mj2",
   "nb_programs" => 0,
   "nb_streams" => 2,
   "probe_score" => 100, 
   "size" => "36936415",
   "start_time" => "0.000000",
   "tags" => %{
     "compatible_brands" => "isomiso2avc1mp41",
     "encoder" => "Lavf58.19.102",
     "major_brand" => "isom",
     "minor_version" => "512"
   }
 }}


  


  Which gives me some information, but not the frame rate.

  


  My next tentative was to use the command options :

  


  command = 
  FFmpex.new_command() 
  |> add_input_file("Devil May Cry 5 Bury the Light LITTLE V COVER.mp4") 
  |> add_video_option(???) 


  


  But the problem here is that I can't find in the documentation the video option I need to get the native frame rate. I only found vframe which is used to set the video frame rate.

  


  Question

  


  

  • How can I get the native fps of a video using ffmpex ?