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• matplotlib ArtistAnimation returns a blank video

  28 mars 2017, par Mpaull

  I’m trying to produce an animation of a networkx graph changing over time. I’m using the networkx_draw utilities to create matplotlib figures of the graph, and matplotlib’s ArtistAnimation module to create an animation from the artists networkx produces. I’ve made a minimum reproduction of what I’m doing here :

  import numpy as np
  
  import networkx as nx
  
  import matplotlib.animation as animation
  
  import matplotlib.pyplot as plt
  
  
  
  # Instantiate the graph model
  
  G = nx.Graph()
  
  G.add_edge(1, 2)
  
  
  
  # Keep track of highest node ID
  
  G.maxNode = 2
  
  
  
  fig = plt.figure()
  
  nx.draw(G)
  
  ims = []
  
  
  
  for timeStep in xrange(10):
  
  
  
      G.add_edge(G.maxNode,G.maxNode+1)
  
      G.maxNode += 1
  
  
  
      pos = nx.drawing.spring_layout(G)
  
      nodes = nx.drawing.draw_networkx_nodes(G, pos)
  
      lines = nx.drawing.draw_networkx_edges(G, pos)
  
  
  
      ims.append((nodes,lines,))
  
      plt.pause(.2)
  
      plt.cla()
  
  
  
  im_ani = animation.ArtistAnimation(fig, ims, interval=200,            repeat_delay=3000,blit=True)
  
  im_ani.save('im.mp4', metadata={'artist':'Guido'})

  The process works fine while displaying the figures live, it produces exactly the animation I want. And it even produces a looping animation in a figure at the end of the script, again what I want, which would suggest that the animation process worked. However when I open the "im.mp4" file saved to disk, it is a blank white image which runs for the expected period of time, never showing any of the graph images which were showed live.

  I’m using networkx version 1.11, and matplotlib version 2.0. I’m using ffmpeg for the animation, and am running on a Mac, OSX 10.12.3.

  What am I doing incorrectly ?

• Returns wrong frame while seeking in FFMPEG Player

  5 février 2015, par user543

  I have implemented an audio player which supports all the formats using FFMPEG. But while seeking the audio, the application is getting the wrong frame at that target duration. Here is my code for the seek functionality.

           int64_t seekTime = av_rescale_q(seekValue * AV_TIME_BASE,
  
                      AV_TIME_BASE_Q,
  
                      fmt_ctx->streams[seekStreamIndex]->time_base);
  
  
  
              int64_t seekStreamDuration =
  
                      fmt_ctx->streams[seekStreamIndex]->duration;
  
  
  
              int flags = AVSEEK_FLAG_BACKWARD;
  
              if (seekTime > 0 && seekTime < seekStreamDuration)
  
                  flags |= AVSEEK_FLAG_ANY;
  
  
  
              int ret = av_seek_frame(fmt_ctx, seekStreamIndex, seek_target,
  
                      flags);
  
  
  
              if (ret < 0)
  
                  ret = av_seek_frame(fmt_ctx, seekStreamIndex, seekTime,
  
                          flags);
  
  
  
            avcodec_flush_buffers(dec_ctx);

  It is working fine for most of the songs.
  But some of the mp3 songs are getting the wrong timespan.

  For instance : If the song total duration is 2 minutes, if I play the song without seeking it works fine. But while playing, if we seek the song to some position, this will make the song ends with 2 mins and 10 seconds.

  I am getting this issue with only mp3 songs. I am using FFMPEG 2.1. The code for the seek functionality is working fine on FFMPEG 0.11.1.

  Please provide any information about this issue.

• Making a thumbnail using fluent-ffmpeg returns ffprobe

  29 avril 2019, par user10204157

  I am getting the following error :

  Error: ffprobe exited with code 1
  
  ffprobe version 4.1.1 Copyright (c) 2007-2019 the FFmpeg developers
  
    built with gcc 8.2.1 (GCC) 20190212
  
    configuration: --enable-gpl --enable-version3 --enable-sdl2 --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass
  
  --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libtheora --enable-libtwolame --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libzimg --enable-lzma --enable-zlib --enable-gmp --enable-libvidstab --enable-libvorbis --enable-libvo-amrwbenc --enable-libmysofa --enable-libspeex --enable-libxvid --enable-libaom --enable-libmfx --enable-amf --enable-ffnvcodec --enable-cuvid --enable-d3d11va --enable-nvenc --enable-nvdec --enable-dxva2 --enable-avisynth
  
    libavutil      56. 22.100 / 56. 22.100
  
    libavcodec     58. 35.100 / 58. 35.100
  
    libavformat    58. 20.100 / 58. 20.100
  
    libavdevice    58.  5.100 / 58.  5.100
  
    libavfilter     7. 40.101 /  7. 40.101
  
    libswscale      5.  3.100 /  5.  3.100
  
    libswresample   3.  3.100 /  3.  3.100
  
    libpostproc    55.  3.100 / 55.  3.100
  
  [tcp @ 0000020813d01740] Connection to tcp://stemuli.blob.core.windows.net:443 failed: Error number -138 occurred  <------
  
  https://stemuli.blob.core.windows.net/stemuli/mentor-lesson-video-76cbf390-4033-4a92-b127-7df22d5885f8.MOV: Unknown error

  Does this mean that azure’s connection is just being cut off ?