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• even though my code is running without an error, it does not generate plot or video. I have xming runing

  23 octobre 2017, par Amin Abbasi

  This is my first code and I am really new to coding. I am trying to create a video or just plot my code.Eeven though my code is running without an error, I can’t get the video or the plot to generate. I have xming running and I have plotted a sample to make sure it not a computer Issue. I have also tried the following on GitHub but no success :
  https://jakevdp.github.io/blog/2013/05/19/a-javascript-viewer-for-matplotlib-animations/

  # -*- coding: utf-8 -*-
  
  import numpy as np
  
  def solver(I, V, f, c, L, dt, cc, T, user_action=None):
  
      """Solve u_tt=c^2*u_xx + f on (0,L)x(0,T]."""
  
      Nt = int(round(T/dt))
  
      t = np.linspace(0, Nt*dt, Nt+1) # Mesh points in time
  
      dx = dt*c/float(cc)
  
      Nx = int(round(L/dx))
  
      x = np.linspace(0, L, Nx+1) # Mesh points in space
  
      C2 = cc**2 # Help variable in the scheme
  
      # Make sure dx and dt are compatible with x and t
  
      dx = x[1] - x[0]
  
      dt = t[1] - t[0]
  
      if f is None or f == 0 :
  
          f = lambda x, t: 0
  
      if V is None or V == 0:
  
          V = lambda x: 0
  
      u       = np.zeros(Nx+1) # Solution array at new time level
  
      u_n     = np.zeros(Nx+1) # Solution at 1 time level back
  
      u_nm1   = np.zeros(Nx+1) # Solution at 2 time levels back
  
      import time; t0 = time.clock() # Measure CPU time
  
      # Load initial condition into u_n
  
      for i in range(0,Nx+1):
  
          u_n[i] = I(x[i])
  
      if user_action is not None:
  
          user_action(u_n, x, t, 0)
  
      # Special formula for first time step
  
      n = 0
  
      for i in range(1, Nx):
  
          u[i] = u_n[i] + dt*V(x[i]) + \
  
              0.5*C2*(u_n[i-1] - 2*u_n[i] + u_n[i+1]) + \
  
              0.5*dt**2*f(x[i], t[n])
  
      u[0] = 0; u[Nx] = 0
  
      if user_action is not None:
  
          user_action(u, x, t, 1)
  
      # Switch variables before next step
  
      u_nm1[:] = u_n; u_n[:] = u
  
      for n in range(1, Nt):
  
          # Update all inner points at time t[n+1]
  
          for i in range(1, Nx):
  
              u[i] = - u_nm1[i] + 2*u_n[i] + \
  
                      C2*(u_n[i-1] - 2*u_n[i] + u_n[i+1]) + \
  
                      dt**2*f(x[i], t[n])
  
          # Insert boundary conditions
  
          u[0] = 0; u[Nx] = 0
  
          if user_action is not None:
  
              if user_action(u, x, t, n+1):
  
                  break
  
          # Switch variables before next step
  
          u_nm1[:] = u_n; u_n[:] = u
  
      cpu_time = time.clock() - t0
  
      return u, x, t,
  
  def test_quadratic():
  
      """Check that u(x,t)=x(L-x)(1+t/2) is exactly reproduced."""
  
      def u_exact(x, t):
  
          return x*(L-x)*(1 + 0.5*t)
  
      def I(x):
  
          return u_exact(x, 0)
  
      def V(x):
  
          return 0.5*u_exact(x, 0)
  
      def f(x, t):
  
          return 2*(1 + 0.5*t)*c**2
  
      L = 2.5
  
      c = 1.5
  
      cc = 0.75
  
      Nx = 6 # Very coarse mesh for this exact test
  
      dt = cc*(L/Nx)/c
  
      T = 18
  
      def assert_no_error(u, x, t, n):
  
          u_e = u_exact(x, t[n])
  
          diff = np.abs(u - u_e).max()
  
          tol = 1E-13
  
          assert diff < tol
  
      solver(I, V, f, c, L, dt, cc, T,
  
              user_action=assert_no_error)
  
  def viz(
  
      I, V, f, c, L, dt, C, T,umin, umax, animate=True, tool='matplotlib'):
  
      """Run solver and visualize u at each time level."""
  
      def plot_u_st(u, x, t, n):
  
          """user_action function for solver."""
  
          plt.plot(x, u, 'r-')
  
  #                 xlabel='x', ylabel='u',
  
  #                 axis=[0, L, umin, umax],
  
  #                 title='t=%f' % t[n], show=True)
  
          # Let the initial condition stay on the screen for 2
  
          # seconds, else insert a pause of 0.2 s between each plot
  
          time.sleep(2) if t[n] == 0 else time.sleep(0.2)
  
          plt.savefig('frame_%04d.png' % n) # for movie making
  
      class PlotMatplotlib:
  
          def __call__(self, u, x, t, n):
  
              """user_action function for solver."""
  
              if n == 0:
  
                  plt.ion()
  
                  self.lines = plt.plot(x, u, 'r-')
  
                  plt.xlabel('x'); plt.ylabel('u')
  
                  plt.axis([0, L, umin, umax])
  
                  plt.legend(['t=%f' % t[n]], loc='lower left')
  
              else:
  
                  self.lines[0].set_ydata(u)
  
                  plt.legend(['t=%f' % t[n]], loc='lower left')
  
                  plt.draw()
  
              time.sleep(2) if t[n] == 0 else time.sleep(0.2)
  
              plt.savefig('tmp_%04d.png' % n) # for movie making
  
      if tool == 'matplotlib':
  
          import matplotlib.pyplot as plt
  
          plot_u = PlotMatplotlib()
  
      elif tool == 'scitools':
  
          import scitools.std as plt # scitools.easyviz interface
  
          plot_u = plot_u_st
  
      import time, glob, os
  
      # Clean up old movie frames
  
      for filename in glob.glob('tmp_*.png'):
  
          os.remove(filename)
  
      # Call solver and do the simulaton
  
      user_action = plot_u if animate else None
  
      u, x, t, cpu = solver_function(
  
          I, V, f, c, L, dt, C, T, user_action)
  
      # Make video files
  
      fps = 4 # frames per second
  
      codec2ext = dict(flv='flv', libx264='mp4', libvpx='webm',
  
                       libtheora='ogg') # video formats
  
      filespec = 'tmp_%04d.png'
  
      movie_program = 'ffmpeg' # or 'avconv'
  
      for codec in codec2ext:
  
          ext = codec2ext[codec]
  
          cmd = '%(movie_program)s -r %(fps)d -i %(filespec)s '\
  
                '-vcodec %(codec)s movie.%(ext)s' % vars()
  
          os.system(cmd)
  
      if tool == 'scitools':
  
          # Make an HTML play for showing the animation in a browser
  
          plt.movie('tmp_*.png', encoder='html', fps=fps,
  
                    output_file='movie.html')
  
      return cpu

• ffmpeg taking time to convert video

  2 septembre 2015, par sonam Sharma

  hello all i am having a video hosting site like youtube where i allow almost all kinds of videos to be uploaded but i would like to convert all the uploaded videos to mp4 format

  i can do this and my code is below

    require 'vendor/autoload.php';
  
          $getEXT_check=substr(@$_FILES['profileimage99']['name'],-3);
  
          if($getEXT_check !='mp4' || $getEXT_check !='MP4'){
  
          exec('ffmpeg -i '.$uploadfile.' -f mp4 -s 896x504 '.$new_flv.''); }
  
          //execute ffmpeg and create thumb
  
          exec('ffmpeg  -i '.$uploadfile.' -ss 00:00:28.435 -vframes 1  '.$new_image_path);
  
          $theduration=exec('ffprobe -v error -show_entries format=duration -of default=noprint_wrappers=1:nokey=1 '.$uploadfile.' 2>&1');
  
          $theduration_val=round($theduration/60, 2);

  this code converts the non mp4 videos to mp4 and gets a thumbnail and gets duration correctly but the problem is that the process takes very much time like more than 2-3 hrs if i upload flv or mkv formats of about 100mbs.

  please suggest me something better please if you need to see the full page code

  Complete Code :

       <?php
  
      @session_start();
  
     include "conn.php";
  
      include "date.php";
  
     $sid = $_SESSION['id'];
  
     $ipIP=$_SERVER['REMOTE_ADDR'];
  
     $uploaddir = "members/$sid/video/";
  
  
  
       //Check the file is of correct format.  
  
        function checkfile($input){
  
        $ext = array('mpg', 'wma', 'mov', 'flv', 'mp4', 'avi', 'qt', 'wmv', 'rm', 'mkv', 'MP4','3gp');
  
        $extfile = substr($input['name'],-4);
  
        $extfile = explode('.',$extfile);
  
          $good = array();
  
        @$extfile = $extfile[1];
  
       if(in_array($extfile, $ext)){
  
       $good['safe'] = true;
  
       $good['ext'] = $extfile;
  
       }else{
  
        $good['safe'] = false;
  
         }
  
        return $good;
  
           }
  
         if($_FILES["profileimage99"]["size"] ==''){
  
       echo 'No file added';die;
  
          }
  
    // if the form was submitted process request if there is a file for uploading
  
     if(@$_FILES["profileimage99"]["size"] < 102400000000){
  
     //$live_dir is for videos after converted to mp4
  
      $live_dir = "mem/$sid/video/";
  
    //$live_img is for the first frame thumbs.
  
      $live_img = "mem/$sid/img/";        
  
      $seed = rand(11111111111193,9999999999999929) * rand(3,9);
  
      $getEXT=substr(@$_FILES['profileimage99']['name'],-5);
  
      $upload = $seed.$getEXT;
  
      $uploadfile = $uploaddir .$upload;        
  
  
  
      $safe_file = checkfile(@$_FILES['profileimage99']);
  
      if($safe_file['safe'] == 1){
  
                  if (move_uploaded_file(@$_FILES['profileimage99']['tmp_name'], $uploadfile)) {
  
  
  
                  $base = basename($uploadfile, $safe_file['ext']);
  
                  $new_file = $base.'mp4';
  
                  $new_image = $base.'jpg';
  
                  $new_image_path = $live_img.$new_image;
  
                  $new_flv = $live_dir.$new_file;
  
  
  
          require 'vendor/autoload.php';
  
          $getEXT_check=substr(@$_FILES['profileimage99']['name'],-3);
  
          if($getEXT_check !='mp4' || $getEXT_check !='MP4'){
  
          exec('ffmpeg -i '.$uploadfile.' -f mp4 -s 896x504 '.$new_flv.''); }
  
          //execute ffmpeg and create thumb
  
          exec('ffmpeg  -i '.$uploadfile.' -ss 00:00:28.435 -vframes 1  '.$new_image_path);
  
          $theduration=exec('ffprobe -v error -show_entries format=duration -of default=noprint_wrappers=1:nokey=1 '.$uploadfile.' 2>&1');
  
          $theduration_val=round($theduration/60, 2);
  
      //create query to store video
  
      if(isset($_POST['title'])){$titlename=$_POST['title'];}else{$titlename='';}
  
      if(isset($_POST['desc'])){$desc=$_POST['desc'];}else{$desc='';}
  
      if(isset($_POST['catag'])){$catag=$_POST['catag'];}else{$catag='';}
  
      if(isset($_POST['channel'])){$channel=$_POST['channel'];}else{$channel='';}
  
      $dbentry_o=mysqli_query($conn,"insert into vids (uid,chid,ctid,vname,vdisc,duration,time,ip,src,thumb) values ('$sid','$channel','$catag','$titlename','$desc','$theduration_val','$date','$ipIP','$new_file','$new_image')");
  
      echo "<img src="http://stackoverflow.com/feeds/tag/mem/$sid/img/$new_image" class="The_Append_L_snap" style='max-width: 300px; max-height: 300px' />";die;
  
           } else {
  
                  echo "Possible file upload attack!\n";
  
                  print_r($_FILES);
  
           }
  
  
  
      }else{
  
  
  
           echo 'Invalid File Type Please Try Again. You file must be of type 
  
           .mpg, .wma, .mov, .flv, .mp4, .avi, .qt, .wmv, .rm'.$_FILES['profileimage99']['name'];
  
  
  
      }
  
    }else{
  
   echo 'Please choose a video';die;
  
    }
  
    ?>

  The issue :
  FFmpeg call above takes too much time to convert the video to MP4.

  Note :
  In the future I will be having a quality selector in my video.js player.

• fate : Use a oneoff test for the tremolo filter

  9 décembre 2019, par Martin Storsjö

  fate : Use a oneoff test for the tremolo filter
  The tremolo filter uses floating point internally, and uses
  
  multiplication factors derived from sin(fmod()), neither of
  
  which is bitexact for use with framecrc.
  This fixes running this test when built with for mingw/x86_32
  
  with clang.
  In this case, a 1 ulp difference in the output from fmod() would
  
  end up in an output from the filter that differs by 1 ulp, but
  
  which makes the lrint() in swresample/audioconvert.c round in a
  
  different direction.
  Signed-off-by : Martin Storsjö <martin@martin.st>
  

  • [DH] tests/fate/filter-audio.mak
  • [DH] tests/ref/fate/filter-tremolo