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• ffmpeg use complex_filter with alphamerge only for a part of the video

  7 mars 2019, par Andy P

  I am trying to apply a filter to only the first few seconds of a video clip - and leave the rest of the video unchanged.

  why ?
  I got some video clips that I wanted to put on a website - unfortunatelly those clips are starting with a black background, which does not fit the website’s design. Therefor I was changing the background to transparent.

  I got that filter working from many of the great answers here (thanks to Gyan) and those videos are playing fine in common browsers :

  ffmpeg -i ${1} -filter_complex "[0]split[m][a];
  
  [a]geq='if(lt(lum(X,Y),16),0,255)',hue=s=0[al];
  
  [m][al]alphamerge,format=yuva420p" -c:v libvpx-vp9 -b:v 0 -crf 18 -an -auto-alt-ref 0 ${1}.webm

  the problem now : of course this replaces all black pixels during the video, which leads to many artefacts later on. Therefor I am searching for a way to apply that filter only to the first 5-ish seconds.

  I think I need a second split and a crop or a trim and a concat filter with a timestamp - but I can’t make it work :(

  ffmpeg -i ${1} -filter_complex "[0]split[f][s];
  
  [f]trim=start=0,duration=5[ft];
  
  [s]trim=start=6[st];
  
  [st]split[m][a];
  
  [a]geq='if(lt(lum(X,Y),16),0,255)',hue=s=0[al];
  
  [m][al]alphamerge,format=yuva420p[mal];
  
  [ft][mal]concat" -c:v libvpx-vp9 -b:v 0 -crf 18 -an -auto-alt-ref 0 ${1}.webm

  /edit : I am changing the subject slighty, to reflect the actual problem.

• ffmpeg overlay transparent animated gif over video and keep gif background transparency

  14 août 2020, par Diego Perez

  I'm trying to overlap an animated gif over a video with no success.

  



  My goals are the next :

  



  

  1. gif animation have to loop until video ends.

  


  2. gif is scaled so it covers the whole video.

  


  3. gif preserves transparency.

  


  



  The most I have achieved regarding this is that the gif covers the whole video with the scale filter and that it loops until video ends (but this not in the best way, I guess).

  



  Regarding loop I know I can use -ignore_loop 0 gif filter parameter with shortest=1 in overlay but this way it is not working so I ended up with -frames:v 900 (my video is 30fps and 30sec long so 900 is the number of frames).

  



  My most important issue is I'm not able to keep gif transparency and everything I've tried resulted in no success.

  



  This is my ffmpeg command with arguments, so I hope anybody can help (I'm using ffmpeg 4.1).

  



  ffmpeg -y 
-i videoin.mp4 
-i anim01.gif 
-filter_complex [1:v]scale=1080:1920[ovrl] [0:v][ovrl]overlay=main_w-overlay_w:main_h-overlay_h
-frames:v 900 
-codec:a copy
-codec:v libx264
-preset ultrafast
video.mp4


  


• How to plot an animated graph

  2 août 2019, par Mukonza Sabastian Simbarashe

  Following along How to Create Animated Graphs in Python when constructing an animated plot then on writing the ffmpeg I get the following error :

  'Requested MovieWriter ({}) not available'.format(name))
  
  RuntimeError: Requested MovieWriter (ffmpeg) not available

  After getting this error, I initially tried to install ffmpeg using pip by the following method :

  python -m install ffmpeg

  and it seems to have successfully installed ffmpeg, but going back to my code I still get the same error

  Find below my code :

  import numpy as np
  
  import pandas as pd
  
  import seaborn as sns
  
  import matplotlib
  
  import matplotlib.pyplot as plt
  
  import matplotlib.animation as animation
  
  
  
  overdoses = pd.read_excel(r'C:\Users\ACER\Desktop\overdose_data_1999-2015.xls',sheet_name='Online',skiprows =6)
  
  
  
  def get_data(table,rownum,title):
  
      data = pd.DataFrame(table.loc[rownum][2:]).astype(float)
  
      data.columns = {title}
  
      return data
  
  
  
  title = 'Heroin Overdoses'
  
  d = get_data(overdoses,18,title)
  
  x = np.array(d.index)
  
  y = np.array(d['Heroin Overdoses'])
  
  overdose = pd.DataFrame(y,x)
  
  overdose.columns = {title}
  
  Writer = animation.writers['ffmpeg']

  Here is the stack trace :

  Traceback (most recent call last):
  
    File "C:\Python\Python36\lib\site-packages\matplotlib\animation.py", line 161, in __getitem__
  
      return self.avail[name]
  
  KeyError: 'ffmpeg'
  
  
  
  During handling of the above exception, another exception occurred:
  
  
  
  Traceback (most recent call last):
  
    File "", line 1, in <module>
  
      Writer = animation.writers['ffmpeg']
  
    File "C:\Python\Python36\lib\site-packages\matplotlib\animation.py", line 164, in __getitem__
  
      'Requested MovieWriter ({}) not available'.format(name))
  
  RuntimeError: Requested MovieWriter (ffmpeg) not available
  
  </module>