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• FFmpeg command to loop an audio starting from a sample twice and add a fade out

  27 juin 2022, par Victor Lopes

  I have some audio files and I want to use FFmpeg to loop them twice, but starting from a given sample (I have the sample numbers), and add a 5 seconds fade-out at the end. The output has to be a video : a static .png on the same folder with the audio playing on top of it (copying the same audio codec to preserve the quality).

  


  For example, for this input audio I am supposed to get this output video. Here I used Audacity to loop and fade the audio starting from the sample 43190, and the following FFmpeg command to add the image to it :

  


  ffmpeg -r 1 -loop 1 -i "Sonic 3 Tile.png" -i "Angel Island Zone Act 1 - LOOP.ogg" -acodec copy -r 1 -shortest -vf scale=1280:1280 "Angel Island Zone Act 1.mkv"


  


  The thing is, I want to be able to do it all at once, using FFmpeg to loop and fade instead of Audacity. Is it possible ? If so, what command should I use ? Just a reminder, the audio has to be looped twice.

  


• Fast seeking ffmpeg multiple times for screenshots

  7 mars 2017, par user3786834

  I have come across http://askubuntu.com/questions/377579/ffmpeg-output-screenshot-gallery/377630#377630, it’s perfect. That has done exactly what I wanted.

  However, I’m using remote URLs to generate the screenshot timeline. I do know it’s possible to fast seek with remote files using https://trac.ffmpeg.org/wiki/Seeking%20with%20FFmpeg (using -ss before the -i) but this only runs the once.

  I’m looking for a way to use the

  ./ffmpeg -i input -vf "select=gt(scene\,0.4),scale=160:-1,tile,scale=600:-1" \
  
  -frames:v 1 -qscale:v 3 preview.jpg

  command but using the fast seek method as it’s currently very slow when used with a remote file. I use PHP but I am aware that a C method exists by using av_seek_frame, I barely know C so I’m unable to implement this into a PHP script I’m writing. So hopefully, it is possible to do this directly with ffmpeg in the PHP system() function.

  Currently, I run seperate ffmpeg commands (with the -ss method) and then combine the screenshots together in PHP. However, with this method it will be refetching the metadata each time and a more optimized method would be to have it all happen in the same command line because I want to reduce the amount of requests made to the remote url so I can run more scripts in sequence with each other.

  Thank you for your help.

• Fast seeking ffmpeg multiple times for screenshots

  14 septembre 2021, par user3786834

  I have come across https://askubuntu.com/questions/377579/ffmpeg-output-screenshot-gallery/377630#377630, it's perfect. That has done exactly what I wanted.

  



  However, I'm using remote URLs to generate the screenshot timeline. I do know it's possible to fast seek with remote files using https://trac.ffmpeg.org/wiki/Seeking%20with%20FFmpeg (using -ss before the -i) but this only runs the once.

  



  I'm looking for a way to use the

  



  ./ffmpeg -i input -vf "select=gt(scene\,0.4),scale=160:-1,tile,scale=600:-1" \
-frames:v 1 -qscale:v 3 preview.jpg


  



  command but using the fast seek method as it's currently very slow when used with a remote file. I use PHP but I am aware that a C method exists by using av_seek_frame, I barely know C so I'm unable to implement this into a PHP script I'm writing. So hopefully, it is possible to do this directly with ffmpeg in the PHP system() function.

  



  Currently, I run seperate ffmpeg commands (with the -ss method) and then combine the screenshots together in PHP. However, with this method it will be refetching the metadata each time and a more optimized method would be to have it all happen in the same command line because I want to reduce the amount of requests made to the remote url so I can run more scripts in sequence with each other.

  



  Thank you for your help.