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• ValueError : I/O operation on closed file when making animation

  3 juillet 2018, par user3851187

  I am using matplotlib and ffmpeg to do some animations. I usually code on a remote server because the code runs faster ; we are having some issues making animations on the remote server. Here is an example of code that works perfectly on my local mac but does not work remotely.

  import matplotlib as mpl
  
  mpl.use('agg')
  
  import matplotlib as mpl 
  
  from matplotlib import animation
  
  import pylab
  
  
  
  def init():
  
      pylab.plot(pylab.arange(10), [0]*10)
  
  
  
  def redraw(frame):
  
      pylab.plot(pylab.arange(10), pylab.arange(10) * frame)
  
  
  
  fig = pylab.figure()
  
  ani = animation.FuncAnimation(fig, redraw, frames=10, interval=1000, init_func=init)
  
  ani.save('animation.mp4')

  I get the animation I want on my local machine (macOS Sierra). When I run it on the remote host (Debian GNU/Linux 8 (jessie)), I get the following error message after 5 frames

  Traceback (most recent call last):
  
    File "animation.py", line 14, in <module>
  
      ani.save('animation.mp4')
  
    File "/usr/local/lib/python2.7/dist-packages/matplotlib/animation.py", line 1200, in save
  
      writer.grab_frame(**savefig_kwargs)
  
    File "/usr/lib/python2.7/contextlib.py", line 35, in __exit__
  
      self.gen.throw(type, value, traceback)
  
    File "/usr/local/lib/python2.7/dist-packages/matplotlib/animation.py", line 241, in saving
  
      self.finish()
  
    File "/usr/local/lib/python2.7/dist-packages/matplotlib/animation.py", line 367, in finish
  
      self.cleanup()
  
    File "/usr/local/lib/python2.7/dist-packages/matplotlib/animation.py", line 405, in cleanup
  
      out, err = self._proc.communicate()
  
    File "/usr/local/lib/python2.7/dist-packages/subprocess32.py", line 724, in communicate
  
      stdout, stderr = self._communicate(input, endtime, timeout)
  
    File "/usr/local/lib/python2.7/dist-packages/subprocess32.py", line 1535, in _communicate
  
      orig_timeout)
  
    File "/usr/local/lib/python2.7/dist-packages/subprocess32.py", line 1591, in _communicate_with_poll
  
      register_and_append(self.stdout, select_POLLIN_POLLPRI)
  
    File "/usr/local/lib/python2.7/dist-packages/subprocess32.py", line 1570, in register_and_append
  
      poller.register(file_obj.fileno(), eventmask)
  
  ValueError: I/O operation on closed file
  
  </module>

  My local machine uses matplotlib version 2.0.0 ; the remote machine uses matplotlib version 2.2.2

  On my local machine I have ffmpeg version 3.2.4

  $ ffmpeg -version
  
  ffmpeg version 3.2.4 Copyright (c) 2000-2017 the FFmpeg developers
  
  built with Apple LLVM version 8.0.0 (clang-800.0.42.1)
  
  configuration: --prefix=/usr/local/Cellar/ffmpeg/3.2.4 --enable-shared - 
  
  -enable-pthreads --enable-gpl --enable-version3 --enable-hardcoded-tables 
  
  --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable libmp3lame --enable-libx264 --enable-libxvid --enable-opencl --disable-lzma --enable-vda
  
  libavutil      55. 34.101 / 55. 34.101
  
  libavcodec     57. 64.101 / 57. 64.101
  
  libavformat    57. 56.101 / 57. 56.101
  
  libavdevice    57.  1.100 / 57.  1.100
  
  libavfilter     6. 65.100 /  6. 65.100
  
  libavresample   3.  1.  0 /  3.  1.  0
  
  libswscale      4.  2.100 /  4.  2.100
  
  libswresample   2.  3.100 /  2.  3.100
  
  libpostproc    54.  1.100 / 54.  1.100 

  On the remote host i have ffmpeg version 4.0.1

  ffmpeg -version
  
  ffmpeg version 4.0.1 Copyright (c) 2000-2018 the FFmpeg developers
  
  built with gcc 4.9.2 (Debian 4.9.2-10+deb8u1)
  
  configuration: --prefix=/usr/local
  
  libavutil      56. 14.100 / 56. 14.100
  
  libavcodec     58. 18.100 / 58. 18.100
  
  libavformat    58. 12.100 / 58. 12.100
  
  libavdevice    58.  3.100 / 58.  3.100
  
  libavfilter     7. 16.100 /  7. 16.100
  
  libswscale      5.  1.100 /  5.  1.100
  
  libswresample   3.  1.100 /  3.  1.100

  If I recall correctly I installed ffmpeg locally through homebrew ; I have the anaconda distribution of python. On the remote machine we have the default version of python that comes with Jessie ; I’m not sure how the sysadmin installed ffmpeg.

  I am by no means an expert on ffmpeg, but I have generally never had issues with making animations in matplotlib on my local machine and I would really like to be able to make videos more quickly on the remote machine. Any help would be appreciated !

  Edit
  On the remote machine, the animation works if I use avconv as the writer instead of ffmpeg. I installed avconv locally...which led me to get the same ffmpeg issues locally (probably due to updating shared dependencies). However, I uninstalled ffmpeg and reinstalled it with x264 codec enables Animations in ipython (jupyter) notebook - ValueError : I/O operation on closed file

• Getting error while converting on FFMPEG ? what's the meaning & how it should be fixed ?

  12 août 2017, par asif

  I am using this code to apply watermark on linux server ;

  -i input.mp4 logo.png -filter_complex 'overlay=main_w-overlay_w-10:main_h-overlay_h-10' output.mp4

  so ended-up with this error ;

  Please use -b:a or -b:v, -b is ambiguous
  
  Cannot find a matching stream for unlabeled input pad 1 on filter Parsed_overlay_0

  Full error ;

  ffmpeg version N-71954-gbc6f84f Copyright (c) 2000-2015 the FFmpeg developers
  
  
  
    built with gcc 4.4.7 (GCC) 20120313 (Red Hat 4.4.7-16)
  
    configuration: --prefix=/usr --enable-version3 --enable-gpl --enable-shared --
  
  
  
  enable-libmp3lame --enable-libvorbis --enable-libtheora --enable-libvpx --
  
  
  
  enable-libx264 --enable-libxvid --enable-libopencore-amrwb --enable-libopencore-
  
  
  
  amrnb --enable-postproc --enable-nonfree --enable-pthreads --enable-x11grab --
  
  
  
  enable-libfaac --enable-libopenjpeg --enable-zlib --disable-doc
  
  
  
    libavutil      54. 23.101 / 54. 23.101
  
    libavcodec     56. 37.101 / 56. 37.101
  
    libavformat    56. 31.102 / 56. 31.102
  
    libavdevice    56.  4.100 / 56.  4.100
  
    libavfilter     5. 16.101 /  5. 16.101
  
    libswscale      3.  1.101 /  3.  1.101
  
    libswresample   1.  1.100 /  1.  1.100
  
    libpostproc    53.  3.100 / 53.  3.100
  
  
  
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'uploaded/1502539665_21.mp4':
  
  
  
    Metadata:
  
      major_brand     : isom
  
      minor_version   : 512
  
      compatible_brands: isomiso2avc1mp41
  
      encoder         : Lavf56.31.102
  
      enter code here
  
  
  
    Duration: 00:02:27.32, start: 0.023220, bitrate: 635 kb/s
  
  
  
      Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 480x320 
  
  [SAR 1:1 DAR 3:2], 476 kb/s, 25 fps, 25 tbr, 12800 tbn, 50 tbc (default)
  
  
  
      Metadata:
  
        handler_name    : VideoHandler
  
      enter code here
  
      Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 151 kb/s (default)
  
      Metadata:
  
        handler_name    : SoundHandler
  
      enter code here
  
  
  
  Please use -b:a or -b:v, -b is ambiguous
  
  Cannot find a matching stream for unlabeled input pad 1 on filter Parsed_overlay_0

• advanced ffmpeg compression control

  18 juillet 2017, par Daniel Mahler

  I am using very aggressive video compression, eg -crf 51. I am using this for ’artistic’ effect, so what I am doing may not make sense from a normal video compression point of view.

  So far I have only been using very basic compression control using only the -crf or -b:v flags. The results look like ffmpeg divides images into square patches and the makes smooth approximations within the patches. This gives 2 control dimensions to the process : the patch size and the aggressiveness of the smoothing within the patches.

  It have found that ffmpeg uses both parameters to some extent, but there appears to be an absolute maximum patch size in pixels beyond which it will not go regardless of the frame size.
  After that it will only increase compression by reducing the detail within the patches.

  This is suboptimal for high resolution video, where this becomes equivalent to reducing the resolution. The problem is particularly noticeable on fractal like images which have large featureless region as well as regions of high detail.

  How can I tell ffmpeg to increase the maximum patch size and retain more detail within the patches ?