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• Generate a movie with ffmpeg from a changing still image url ?

  24 septembre 2012, par Wim Deblauwe

  I need to create a movie/stream with ffmpeg from a HTTP url that points to an image. This image gets updated 1 time per second.

  I already know how to convert from MPEG-4 to flv for example using the ffmpeg command line, but now I need to start from this still image that gets updated. I would like ffmpeg to 'GET' the url 1 time per second for example.

  regards,

  Wim

• Rescaling and slowing down a movie at the same time with ffmpeg

  21 décembre 2016, par ejl62

  I would like with ffmpeg to slow down a movie I am creating using the flag :

  -filter:v "setpts=2.0*PTS"

  However the height of my still images is not divisible by 2, so to avoid the error : height not divisible by 2 (1238x833), I am using the flag :

  -vf scale="trunc(iw/2)*2:trunc(ih/2)*2"

  (I also tried -vf scale=1238:-2).

  When I do this the film is generated but it isn’t slowed down, like if the -filter:v "setpts=2.0*PTS" wasn’t there.

  Is there something particular to do in order to have both option working at the same time ?

  Here is the complete command I am using :

  ffmpeg -an -i ./movie/cphmd1.%05d.ppm -vcodec libx264 -pix_fmt yuv420p -b:v 5000k -r 24 -crf 18 -filter:v "setpts=2.0*PTS" -vf scale="trunc(iw/2)*2:trunc(ih/2)*2" -preset slow -f mp4 cphmd1_slower.mp4

  Many thanks in advance !

• create a movie in python [on hold]

  22 mai 2017, par masoud

  I have some files with names (’Den_car_resample’ +’sdf’+ str(n)+’.dat’) where n changes from 0 to 25. I wrote a code to read these files and plots the results.
  now I want to create a movie from these plots. at the end of the program, I used the avconv command to do that.
  but, unfortunately my code creates a movie but it is empty.
  I don’t know the reason exactly but I think, first, I have to define a frame to each plot and then create a movie.
  can anyone please tell me how can I define a frame and also the add bit_rate of the movie.

  import sys
  
  import subprocess   
  
  import sdf
  
  import numpy as np
  
  import matplotlib.pyplot as plt  
  
  import time
  
  import matplotlib.animation as Animation
  
  from matplotlib.font_manager import FontProperties
  
  fp = FontProperties('Symbola')
  
  
  
  ##################### information from EPOCH input.deck
  
  nx,ny= 1200, 1600
  
  xmin=-100e-6
  
  xmax = 110e-6
  
  ymin = -200e-6
  
  ymax = 200e-6
  
  X =np.linspace(xmin,xmax,nx)   
  
  Y =np.linspace(ymin,ymax,ny)
  
  
  
  #################
  
  for n in range(0,25):
  
    nstr = str(n)
  
  
  
  ######################..... reading Density of carbon
  
    filename ="Den_car_resample" +'_sdf_'+ str(n)+'.dat'
  
  
  
    with open(filename, 'rb') as f:                        
  
      data = np.fromfile(f, dtype='float64', count=nx*ny)  
  
  
  
    Den_car  = np.reshape(data, [ny, nx], order='F')
  
    Den_car= np.log10(Den_car)
  
  
  
    ######################  Display Carbon density
  
  
  
    fig = plt.imshow(Den_car,  extent=[X.min()*1e6, X.max()*1e6, Y.min()*1e6,Y.max()*1e6], vmin=24, vmax=29, cmap='brg', aspect='auto') 
  
    plt.suptitle('Den_car')
  
    plt.title('sdf '+ str(n)+'; Time= '+str(n*50)+'ps',color='green', fontsize=15)
  
    plt.xlabel('x($\mu$m)')
  
    plt.ylabel('y($\mu$m)')
  
    plt.text(-80,-40,'Den_Carbon',color='red', fontsize=15)
  
    plt.colorbar()
  
    plt.savefig( 'fig%06d.png' % n, bbox_inches='tight')          
  
  
  
    plt.pause(.1)
  
    plt.clf()  
  
    plt.close()
  
  
  
    ######################  Create movie
  
  
  
    subprocess.call("avconv -framerate 1 -i fig%06d.png -c:v libx264 -profile:v high -crf 20".split())
  
  
  
  sys.exit()