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• Creating a smooth animation with ffmpeg filters

  30 mai 2021, par user1503606

  I am trying to add a watermark to a video using ffmpeg and have it animated from left to right in the center of the video.

  


  I have it working with the following command.

  


  ffmpeg -y -i Volkswagen.mp4 -loop 1 -i logo.png -filter_complex overlay=x='W/30*mod(t,30):enable=gt(mod(t,60),0)':y=main_h/2-overlay_h/2:shortest=1 Volkswagen_watermarked.mp4


  


  It works but the outcome looks like this.

  


  https://www.youtube.com/watch?v=M31wG2ub1Lg

  


  The video is from here : https://gist.github.com/jsturgis/3b19447b304616f18657

  


  http://commondatastorage.googleapis.com/gtv-videos-bucket/sample/VolkswagenGTIReview.mp4

  


  As you can see its not very smooth. I am just trying to get my head around the ffmpeg filter functions this is the first time I have used them so would appreciate some advise or is this as good as it gets ?

  


  I have looked at a few other posts but cant find any that can help with this maybe there is another filter I should be using ?

  


  I can run a draw filter command like this and the animation is smoother.

  


  ffmpeg -y -i Volkswagen.mp4 -vf "drawtext=fontfile=/Montserrat-Medium.ttf:text='Text':x=200:y=h-20*t: fontsize=36:fontcolor=yellow@0.9: box=1: boxcolor=black@0.6" -c:a copy VolkswagenText.mp4


  


  But it is obviously not looping.

  


  https://www.youtube.com/watch?v=wdANCWUHaMc

  


  I dont really understand whats happening here.

  


  w*mod(t\,10):enable=gt(mod(t\,60)\,0)

w = width of text
t = time in seconds


  


  I understand if I just have this.

  


  -filter_complex "overlay=x=w*t:y=main_h/2-overlay_h/2:shortest=1"

w*t = every second the x position is incremented by the text width * time


  


  so if the text width is 100px it would be something like this.

  


  1x100 = 100;
2x100 = 200;
etc


  


  What does the mod() function do ? I cant find any help really here https://ffmpeg.org/ffmpeg-filters.html

  


  is this saying when x is greater than the width of the viewport start again ?

  


  enable=gt(mod(t\,60)\,0)


  


  Thanks

  


• c# using pipes to get output stream

  1er janvier 2017, par lilscarecrow

  I am trying to pipe youtube-dl output to ffmpeg as input, but cannot seem to get the piping part to work. In normal cmd, I can do something like

   C:\YT\youtube-dl.exe -o - https://www.youtube.com/watch?v=L4aLQ0ki9Tk | ffmpeg -i pipe:0 -f asf pipe:1 

  but in c# this doesn’t work. Currently, I have c# create 2 processes :

  one for youtube-dl

  C:\YT\youtube-dl.exe -o - https://www.youtube.com/watch?v=L4aLQ0ki9Tk

  and another for ffmpeg

  ffmpeg  -i {yt.StandardOutput} -f s16le -ar 48000 -ac 2 pipe:1

  The problem is with the {yt.StandardOutput} (where yt is the process name of the youtube-dl process and -i specifies the input file/stream). Using pipe:0 doesn’t work either and I am not sure how to link the piped output of the first to the input of the second.

• How to create video with dynamic pictures like Facebook Friend's Day video

  21 février 2019, par Vinicius

  How to create a video with pictures from a user just like Facebook does with their Facebook Friend’s day video ?

  Example : https://www.youtube.com/watch?v=mNWJ_XxfQfU

  The intention is to generate this sort of video with images that a visitor will upload to a website. FFMPEG does support images animation but it seems that a bit of 3d animations like the above needs ages to be done with FFMPEG. I wonder if there is an alternative to FFMPEG that can generate this sort of animations, or maybe a software like After Effects that can either generate a template that can be used on ffmpeg (or any command line alternative) or has its own command-line interface that can be executed in a linux machine to do such thing.

  Basically, the user would upload the pictures, the server would crop them to have the same size and then it would convert it to a video like the one mentioned above.