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• How to detect the silence at the end of an audio file ?

  1er mars 2017, par Ali Akber

  I am trying to detect silence at the end of an audio file.
  I have made some progress with ffmpeg library. Here I used silencedetect to list all the silences in an audio file.

  ffmpeg -i audio.wav -af silencedetect=n=-50dB:d=0.5 -f null - 2> /home/aliakber/log.txt

  Here is the output of the command :

  —With silence at the front and end of the audio file—

  [silencedetect @ 0x1043060] silence_start: 0.484979
  
  [silencedetect @ 0x1043060] silence_end: 1.36898 | silence_duration: 0.884
  
  [silencedetect @ 0x1043060] silence_start: 2.57298
  
  [silencedetect @ 0x1043060] silence_end: 3.48098 | silence_duration: 0.908
  
  [silencedetect @ 0x1043060] silence_start: 4.75698
  
  size=N/A time=00:00:05.56 bitrate=N/A

  —Without silence at the front and end of the audio file—

  [silencedetect @ 0x106fd60] silence_start: 0.353333
  
  [silencedetect @ 0x106fd60] silence_end: 1.25867 | silence_duration: 0.905333
  
  [silencedetect @ 0x106fd60] silence_start: 2.46533
  
  [silencedetect @ 0x106fd60] silence_end: 3.37067 | silence_duration: 0.905333
  
  size=N/A time=00:00:04.61 bitrate=N/A

  But I want something more flexible so that I can manipulate the output and do further task depending on the result.
  I want to get the output something like true or false. If there is a certain period of silence exists at the end of the audio file it will return true and false otherwise.

  Can someone suggest me an easy way to achieve this ?

• 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 ?

• How to cut the videos per every 2MB using FFMpeg

  5 mai 2017, par Krish

  Hi i have 20MB size video,I need to split this video as each part should be 2MB,
  For this i google it and found FFMpeg library for splitting videos.

  But this library splitting the videos based on time-limit suppose (00:00:02 to 00:00:06 seconds,Between this time period video splitted)

  My requirement is, I want to cut the video per every 2MB that’s what my exact requirement not based on time limit.

  I searched for this lot in google but i did not get solution can some one help me please.

  FFMpeg Command i used for splitting :-

  String cmd[] = new String[]{"-i", inputFileUrl, "-ss", "00:00:02", "-c", "copy", "-t", "00:00:06",
  
                  outputFileUrl};
  
          executeBinaryCommand(fFmpeg, cmd);
  
  
  
   public void executeBinaryCommand(FFmpeg ffmpeg, String[] command) {
  
  
  
          try {
  
  
  
              if (ffmpeg != null) {
  
  
  
                  ffmpeg.execute(command,
  
                          new ExecuteBinaryResponseHandler() {
  
  
  
                              @Override
  
                              public void onFailure(String response) {
  
                                  System.out.println("failure====>" + response.toString());
  
                              }
  
  
  
                              @Override
  
                              public void onSuccess(String response) {
  
                                  System.out.println("resposense====>" + response.toString());
  
                              }
  
  
  
                              @Override
  
                              public void onProgress(String response) {
  
                                  System.out.println("on progress");
  
                              }
  
  
  
                              @Override
  
                              public void onStart() {
  
                                  System.out.println("start");
  
                              }
  
  
  
                              @Override
  
                              public void onFinish() {
  
                                  System.out.println("Finish");
  
                              }
  
                          });
  
              }
  
          } catch (FFmpegCommandAlreadyRunningException exception) {
  
              exception.printStackTrace();
  
          }
  
      }