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• Save Slow motion video with ffmpeg on android devices

  25 mars 2017, par nkalra0123

  I want to save videos in slow motion through my android app.I tried to convert videos into slow motion by changing frame rate.

  I used the following commands,first command is dumping 30 frames per second from videos to a temp directory, and then second command is using these images to create a video with reduced or faster frame rate and then i am deleting all the images from temp directory.

  ffmpeg -i input_file.mp4 -r 30/1 img%03d.png
  
  
  
  ffmpeg -framerate 15/1 -i img%03d.png -r 30 -pix_fmt yuv420p out4.mp4

  But this is a very slow operation. It is taking like forever even for small videos.

  I even tried to change PTS(presentation time stamp) of videos, but it is not working properly on android phones
  using this command :

  ffmpeg -i input.mkv -filter:v "setpts=2.0*PTS" output.mkv

  as suggested here :
  https://trac.ffmpeg.org/wiki/How%20to%20speed%20up%20/%20slow%20down%20a%20video

  Can anybody suggest me how can i make it fast. Is it necessary to save frames to a temp directory, can i pass the output of ffmpeg process to another ffmpeg process executing concurrently through some method.

  Is there any other ffmpeg command to save the videos in slow motion ?

• FFMPEG - build ubuntu 32 bit - missing shared library : libspeex

  29 avril 2013, par Benoit Brayer

  I am currently doing a cross platform software calling ffmpeg in c++ and I need a ffmpeg build working on both ubuntu 32bits and 64bits for the installer.
  I also need this ffmpeg build to include librtmp, libh264, x11-grab, alsa, and mp3.

  I tried to compile ffmpeg on a 32bits virtual box to have a ffmpeg build working on ubuntu 32 bits and 62 bits.

  I used this guide to build ffmpeg :
  https://ffmpeg.org/trac/ffmpeg/wiki/UbuntuCompilationGuide

  After compiling all the libs and ffmpeg himself, after installation using the deb files, ffmpeg is working perfectly on the 32bits virtualbox with all of my required components but not on my 62bits ubuntu.

  When executing ffmpeg on ubuntu 64bits i got a message saying : impossible find the shared library libspeex.

  Do you have any idea why I have this problem only on linux 64bits with the save deb files ?
  Do you know a website where i could find an ffmpeg 32bits build with all the components I need (static if possible) ?
  I tried this website http://ffmpeg.gusari.org/static/ but the build is not including alsa...

  I have a build for windows working perfectly, I downloaded the 32 bits static build on this website : zeranoe builds website for windows.

  Thanks in advance for any answer.
  Regards.

  Benoit Brayer

• Use ffmpeg to create a music video with the cover on a black background

  21 septembre 2020, par user6329530

  I am trying to use this tutorial to create youtube videos with ffmpeg
https://trac.ffmpeg.org/wiki/Encode/YouTube

  


  When using this example, I get a video that works however the background is white

  


  ffmpeg -loop 1 -framerate 2 -i albumcover.png -i audio.wav -c:v libx264 -preset medium -tune stillimage -crf 18 -c:a copy -shortest -pix_fmt yuv420p output.mkv


  


  I tried to add a color filter but that makes the whole video output black :

  


  ffmpeg -loop 1 -framerate 2 -i albumcover.png -filter_complex "color=s=1920x1080:c=black" -i audio.wav -c:v libx264 -preset medium -tune stillimage -crf 18 -c:a copy -shortest -pix_fmt yuv420p output.mkv


  


  I find it very difficult to find something about this on the internet as most ask for just a black video or a transparent background for a gif ect.

  


  So how do I get the albumcover.png on a black background ?

  


  EDIT : I just realized that the video format is of course the image format (square) and therefore it's white on youtube. The question therefore is now how do I create a black background 16:9 and put the albumcover centered on it...