Recherche avancée

Sur d’autres sites (10846)

• doc/general : update after recent additions

  25 octobre 2015, par Paul B Mahol

  doc/general : update after recent additions
  Signed-off-by : Paul B Mahol <onemda@gmail.com>
  

  • [DH] doc/general.texi
  • [DH] libavformat/vag.c

• Creating a convertAll() function that converts all .filetype in working directory

  5 janvier 2019, par Risviltsov

  I seem to not know proper bash syntax ; despite this, I’ve tried to create a tool that changes the dimensions of all files of a ffmpeg-accepted filetype in the working directory and converts it to another ffmpeg-accepted filetype. In this instance, this tool converts all .webm files over 1080x720 into 1080x-1 or -1x720 .mp4 files. If the .webm file is under 1080x720, the new .mp4 file will have the same dimensions.

  However, there’s a wrench in the tool.

  convertAll () {
  
  local wantedWidth = 1080
  
  local wantedHeight = 720
  
  for i in *.webm; do
  
  local newWidth = $i.width
  
  local newHeight = $i.height
  
  until [$newWidth <= $wantedWidth && $newHeight <= $wantedHeight]; do
  
  if [$videoWidth > $wantedWidth]; then
  
  newHeight = $newWidth*($wantedWidth/$newWidth)
  
  newWidth = $newWidth*($wantedWidth/$newWidth)
  
  fi
  
  if [$videoHeight > $wantedHeight]; then
  
  newWidth = $newWidth*($wantedHeight/$newHeight)
  
  newHeight = $newHeight*($wantedHeight/$newHeight)
  
  fi
  
  done
  
  ffmpeg -i "$i" -vf scale=$newWidth:$newHeight "${i%.*}.mp4";
  
  done
  
  echo "All files have been converted."
  
  }

  What this returns is a bunch of lines that look like this :

  bash: [: missing ']'
  
  bash: [: missing ']'
  
  bash: =: No such file or directory

  My best guess is that BASH can’t do mathematics, and that I’m declaring and editing my variables incorrectly.

  I’d like some input on this --- my lack of experience is really getting me here.

• FFMpeg amix filter volume changes. Explanation request

  22 janvier 2020, par klodoma

  First, the question :
  IS THERE somewhere documented or explained how ffmpeg amix filter changes the volume in the mixed audio files ? I couldn’t find any good reference.

  There are several threads regarding this "issue" that the amix filter changes the volume of the input files. I played around with these and I just cannot explain what is going on. It makes a difference if you "mix" files like concatenate them at specific times or you overlap audio tracks and volume changes just doesn’t make any sense.

  Firstly, I don’t understand WHY the volumes need to be changed.

  Some related refs :

  • FFMPEG amix filter volume issue with inputs of different duration
  • FFMPEG set volume in amix