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• How do I crossfade between scenes in ffmpeg using a complex filter ?

  15 mars 2014, par scubed

  I have ffmpeg 2.1.4 and an input movie in.mkv.
  There are effectively 2 different scenes inside of in.mkv. I want to be able to crossfade between the scenes, preferably with just using a complex filter instead of external programs. Essentially, I want to have something like an overlay but with the alpha changing at a specific time.

  Consider if in.mkv looked like this :

  00:00 - 00:05 scene 1
  
  00:05 - 00:10 junk
  
  00:10 - 00:15 scene 2

  So, I would want an output that had :

  00:00 - 00:04 scene 1 (0-4)
  
  00:04 - 00:05 alpha fading between scene 1 (4-5) and 2 (10-11)
  
  00:05 - 00:09 scene 2 (11-15)

  I see that there's a filter for : overlay, alphamerge, and color, but it's not clear how exactly to do this.

  In general, it seems hard to work with pieces of a movie file in ffmpeg. Is there a way to say that I am taking various pieces of the same input file and putting them together without rendering them as separate movies first ?

• Running ffmpeg with Mac's Automator to remove metadata

  11 février 2019, par sd100

  Hi so I am having problems running ffmpeg on a folder of movie files with Mac’s automator. My goal is to select a folder and right click/select service and automatically the script should run on only movie files (of mp4 type).

  So I have a Automator workflow receives files or folders in finder. Then I have "Selected Finder items" and then run shell script (code below).

  This works but firstly it gives the ffmpeg verbose output in the results window in the mac which I have to press ok. I tried the "-hide_banner -loglevel panic" but the script doesn’t work then.

  Secondly the "Selected finder items" works but I want to only select a folder and automatically the automator script should go in the folder and run the shell script on only mp4 files (movie).

  Is there anyway to set both requirements ? Any advise would be appreciated !

  Code I’ve tried :

  for f in "$@"
  do
  /usr/local/bin/ffmpeg -i "$f" -map_metadata -1 -c:v copy -c:a copy "$f%.mp4"-new.mp4 ;
  done

  Also am trying to move all converted mp4 files to a directory in the current directory with shell code like this :

  for f in *.mp4 ; do ffmpeg -i "$f" -map_metadata -1 -c:v copy -c:a copy "converted/$f" ; done

  This doesn’t work either in automator as I don’t know how to move the ffmpeg output files into another directory via automator.

• Converting PNG images to MP4 in Jupyter

  15 mars 2020, par Steve H

  This has had me going round in circles for hours, so I’m hoping one of you kind gents can help.

  I am trying to learn more about data science and have followed this course on creating a population pyramid (https://www.viralml.com/video-content.html?v=WmyYyOtZwzs). There were a few problems in the code, which I rectified, but one has eluded me.

  I am trying to convert a collection of images in the format anim_%d.png to an mp4 file using the code :

  ffmpeg -framerate 10 -i "anim_%d.png" -pix_fmt yuv420p out.mp4

  However, I get an invalid syntax error.

  I have also tried :

  avconv -f image2 -i anim_%d.png -r 76 -s 800x600 foo.avi

  then :

  ffmpeg -r 10 -i "anim_%d.png" -pix_fmt yuv420p out.mp4

  But they all give a syntax error.

  I am using Jupyter, via Anaconda on a Windows machine with Python 3.

  Any help would be greatly appreciated.

  Thanks
  Steve