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• Precise image overlay over video using ffmpeg

  22 août 2017, par Sunny Tambi

  I want to overlay various icon-images over a given video (which is created using the sequence of images) in a time and position precise manner. I am using FFmpeg for the same.
  Here are the commands I am using :

  Image to video conversion command

  ffmpeg -framerate 5 -start_number 0 -i images/img%04d.png -vframes 1000 -r 30 -vcodec libx264 -crf 25  -pix_fmt yuv420p out.mp4 -y

  Images superimpose over video command

  ffmpeg -analyzeduration 10000 -hwaccel auto -i out.mp4 -i icons/up.png -i icons/down.png -i icons/left.png -i icons/right.png -i icons/top.png -i icons/bottom.png -i icons/side.png -filter_complex [0:v]setpts=PTS-STARTPTS[0];
  
  [1:v]setpts=PTS-STARTPTS[i1];
  
  [2:v]setpts=PTS-STARTPTS[i2];
  
  [3:v]setpts=PTS-STARTPTS[i3];
  
  [4:v]setpts=PTS-STARTPTS[i4];
  
  [5:v]setpts=PTS-STARTPTS[i5];
  
  [6:v]setpts=PTS-STARTPTS[i6];
  
  [0][i1]overlay=211.875:319.916:enable='between(t,0.610,0.910)'[1];
  
  [1][i2]overlay=212.344:309.516:enable='between(t,1.810,2.110)'[2];
  
  [2][i3]overlay=37.969:332.396:enable='between(t,2.775,3.075)'[3];
  
  [3][i4]overlay=202.500:307.436:enable='between(t,3.626,3.926)'[4];
  
  [4][i5]overlay=37.734:296.203:enable='between(t,4.531,4.831)'[5];
  
  [5][i6]overlay=208.359:313.676:enable='between(t,5.602,5.902)'[6];
  
  [6][i7]overlay=34.688:383.150:enable='between(t,6.733,7.033)'[7];
  
  -map [7] -y -movflags +faststart superimposed.mp4

  My problem is that I am not getting precision in time. i.e. if there is an icon to be overlayed at 0.61 sec, it doesn’t come exactly at 0.61 sec. Sometimes it comes at 1.0 sec, sometimes at 0.30 sec and sometimes at some other unpredictable time.

  I have an HTML5 video player where the user is allowed to seek the video with 100-millisecond precision. The user expects the icon to see precisely at 0.61 sec. However, above inaccuracy limits the capabilities of my video player.

  Please suggest what could be wrong in my implementation/command.

• Psychopy gives the ffmpeg error and does not play the videos

  17 août 2017, par I.Nuel

  I want to create an experiment with Psychopy in which I will present randomly video that participant will have to evaluate.

  I have created a routine with my MovieStim and my Rating response and a Loop with my conditions file (in which are my video files videoname.wmv).
  All my videos are in the same folder as my experiment.

  I have specified the MovieStim with a variable refering to my Loop’s column ($Stimulus).

  But when I run the experiment I have this message.

  Running: E:\Thèse ESPRIT\Approach_Aversion\Experience_AA\Approach_Aversion_lastrun.py 
  
  pyo version 0.8.0 (uses single precision)
  
  WARNING:root:Warning: could not find imageio's ffmpeg executable:
  
  [Error 5] Accès refus: 'C:\\Program Files (x86)\\PsychoPy2\\lib\\site-packages\\imageio\\resources\\ffmpeg\\ffmpeg.win32.exe'
  
  Traceback (most recent call last):
  
    File "E:\Thèse ESPRIT\Approach_Aversion\Experience_AA\Approach_Aversion_lastrun.py", line 105, in <module>
  
      depth=0.0,
  
    File "C:\Program Files (x86)\PsychoPy2\lib\site-packages\psychopy-1.84.2-py2.7.egg\psychopy\contrib\lazy_import.py", line 120, in __call__
  
      return obj(*args, **kwargs)
  
    File "C:\Program Files (x86)\PsychoPy2\lib\site-packages\psychopy-1.84.2-py2.7.egg\psychopy\visual\movie3.py", line 124, in __init__
  
      self.loadMovie(self.filename)
  
    File "C:\Program Files (x86)\PsychoPy2\lib\site-packages\psychopy-1.84.2-py2.7.egg\psychopy\visual\movie3.py", line 170, in loadMovie
  
      self._mov = VideoFileClip(filename, audio=(1 - self.noAudio))
  
    File "C:\Program Files (x86)\PsychoPy2\lib\site-packages\moviepy\video\io\VideoFileClip.py", line 55, in __init__
  
      reader = FFMPEG_VideoReader(filename, pix_fmt=pix_fmt)
  
    File "C:\Program Files (x86)\PsychoPy2\lib\site-packages\moviepy\video\io\ffmpeg_reader.py", line 32, in __init__
  
      infos = ffmpeg_parse_infos(filename, print_infos, check_duration)
  
    File "C:\Program Files (x86)\PsychoPy2\lib\site-packages\moviepy\video\io\ffmpeg_reader.py", line 237, in ffmpeg_parse_infos
  
      proc = sp.Popen(cmd, **popen_params)
  
    File "C:\Program Files (x86)\PsychoPy2\lib\subprocess.py", line 710, in __init__
  
      errread, errwrite)
  
    File "C:\Program Files (x86)\PsychoPy2\lib\subprocess.py", line 958, in _execute_child
  
      startupinfo)
  
  WindowsError: [Error 2] Le fichier spécifié est introuvable
  
  </module>

  It seems to be something wrong with the ffmpeg executable but I don’t understand what.

  Do you have any idea ?

  Thank you very much fo advance !

  Have a nice day.

  Ivane

• lavf/matroskaenc : fix avio_printf argument types after bump

  4 avril 2021, par Anton Khirnov

  lavf/matroskaenc : fix avio_printf argument types after bump
  Field precision supplied with the '*' specification must be an int.
  Also, make sure converting those fields to int does not overflow.
  

  • [DH] libavformat/matroskaenc.c