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• Filter concat:out:v0 has a unconnected output | Concatenating with php-ffmpeg

  9 février 2016, par K Ф

  I’m incorporating PHP-FFMpeg to my symfony3 project which is working perfectly. However recently I’ve been needing to concatenate two videos into one, and it would appear it’s not supported. So I created a ConcatVideoFilter class that I’m using based off of this

      public function apply(Video $video, VideoInterface $format)
  
      {
  
          $params = [];
  
          $count = count($this->files) + 1;
  
          foreach ($this->files as $i => $file) {
  
              $params[] = '-i';
  
              $params[] = $file;
  
          }
  
          $params[] = '-filter_complex';
  
          $params[] = 'concat=n='.$count.':v=1:a=1 [v]';
  
          $params[] = '-map';
  
          $params[] = '[v]';
  
          return $params;
  
      }

  I’m getting an encoding failed error in my symfony profiler

  

  I then copy pasted the actual ffmpeg command line to see what error it would give :

  

  Which is giving me this error

  Filter concat:out:v0 has a unconnected output

  What does this error mean, and what can I do to get rid of it ?

• Ffmpeg : Concat multiple videos and an audio file. Videos may or may not have audio and I cant know it before runnign the command

  28 juillet 2023, par AtActionPark

  I have a list of mp4 and an aac audio file. I have a concat.txt file with all the mp4s that need to be concatenated.
I need to concat all the mp4s and merge the aac on top.

  


  As said in the title, the mp4s individually may or may not have an audio track, and I can not check the mp4s with no audio, add a dummy sound track as it will be an automated process with thousands of commands executed daily.

  


  The sound of the mp4, if present, must be preserved and merged with the aac

  


  Here is a working command for the case where at least the first of my mp4s has an audiotrack :

  


  ffmpeg -f concat -safe 0 -i concat.txt -i audio.aac  -c:v copy -filter_complex "[0:a][1:a] amix=inputs=2:duration=shortest [audio_out]" -map 0:v -map "[audio_out]" -y result.mp4


  


  However that breaks if my mp4s dont have audio

  


  


  Stream specifier ':a' in filtergraph description [0:a][1:a]
amix=inputs=2:duration=shortest [audio_out] matches no streams.

  


  


  I've been reading about anullsrc, and would like to take [0:a] if it exists, or a generated empty audio channel, and merge it with my aac, but I'm not getting there.

  


  Any help would be appreciated

  


  Thanks

  


• Concat creates a still image before the video

  7 décembre 2017, par Vitalis Hommel

  I am creating a cutlist like this

  file 't1.MP4'
  
  inpoint 1.45067
  
  outpoint 3.18133
  
  file 't2.MP4'
  
  inpoint 3.45067
  
  outpoint 6.18133
  
  ...

  and I use it like this

  ffmpeg -y -f concat -safe 0 -i list.txt -c:v libx264 -c:a aac -af aresample=async=1 -pix_fmt yuv420p output.mp4

  The output almost always contains a still image at the start, sometimes half the video time, sometimes less, showing the first frame then the final video starts. I noticed, the less inpoint and outpoint are apart, the longer the still image at the start. Maybe its also connected to the amount of inpoint and outpoint.

  How do I solve this ?