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• FFmpeg : Add alpha channel to a video using a PNG mask

  7 avril 2016, par Rodrigo Polo

  I saw that FFmpeg can merge/blend two videos with alpha channel and can encode video with alpha channel using the qtrle codec, but, It is possible to apply a PNG file mask, either a black and white or a PNG with an alpha channel to a video in order to have a video with the alpha channel of the PNG applied ?

  Here is the concept in images

  Original video :
  

  PNG file with alpha channel, the "mask" :
  

  And the result :
  

  Or even a black and white image as a mask for alpha channel :
  

  Any help would be appreciated, thank you !

• How to swap SBS LR 3D videos ?

  21 avril 2016, par Vitalis Hommel

  I have this command

  ffmpeg -i "D:\Neuer Ordner\Test.mkv" -c copy -ss 00:00:00 -t 00:08:00 -sn "D:\Neuer Ordner\Test1.mkv" -c copy -ss 00:08:00 -t 00:08:00 -sn "D:\Neuer Ordner\Test2.mkv" -c copy -ss 00:16:00 -t 00:08:00 -sn "D:\Neuer Ordner\Test3.mkv" -c copy -ss 00:24:00 -sn "D:\Neuer Ordner\Test4.mkv"

  My goal is to upload them to youtube. Yet I need to swap each pair before converting it, so left becomes right and right becomes left.

  I found the complex filter and tried

  ffmpeg -i "D:\Neuer Ordner\Test.mkv" -filter:v "crop=1280:720:0:0" -i "D:\Neuer Ordner\Test.mkv" -filter:v "crop=1280:720:1280:0" -filter_complex "pad=in_w*2:in_h, overlay=main_w/2:0, scale=in_w/2:in_h, scale=-1:720" -c:a copy "D:\Neuer Ordner\output.mkv" 

  Which led to

  Option filter:v (set stream filtergraph) cannot be applied to input file D:\Neuer Ordner\Test.mkv -- you are trying to apply an input option to an output file or vice versa. Move this option before the file it belongs to. 
  
  Error parsing options for input file D:\Neuer Ordner\Test.mkv. 
  
  Error opening input files: Invalid argument

  Which command solves this ?

• Trying to open file with PHP-FFMpeg after it was encoded once

  19 mai 2016, par Shillo Ben David

  in the same PHP process I’m trying to open a file that was manipulated and saved, and then I’m trying to open it with as a new FFMpeg\Video. For example, in the same process :

  Open -> original.MOV
  
    Manipulate & save to -> new.mp4
  
      Open -> new.mp4

  However when I’m trying to open the manipulated file I get this InvalidArgumentException exception :

  InvalidArgumentException: Unable to detect file format, only audio and video supported

  It’s thrown by the FFMpeg::open() after it could not detect that it’s a either Video or Audio stream.

  FFMpeg::open()

  public function open($pathfile)
  
  {
  
      if (null === $streams = $this->ffprobe->streams($pathfile)) {
  
          throw new RuntimeException(sprintf('Unable to probe "%s".', $pathfile));
  
      }
  
  
  
      if (0 < count($streams->videos())) {
  
          return new Video($pathfile, $this->driver, $this->ffprobe);
  
      } elseif (0 < count($streams->audios())) {
  
          return new Audio($pathfile, $this->driver, $this->ffprobe);
  
      }
  
  
  
      throw new InvalidArgumentException('Unable to detect file format, only audio and video supported');
  
  }

  The filters I applied to the video are audio mute and speedup (setpts).

  So I wonder, why FFMpeg doesn’t recognise it as video ?