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• Output result of concat demuxer to pipe

  19 mars 2023, par ZPears

  I am trying to output the results of an ffmpeg call that concatenates videos to a pipe. Here's the command :

  


  ffmpeg -protocol_whitelist https,file,tls,tcp -f concat -safe 0 -i <(for f in "/path/to/file1.mp4" "/path/to/file2.mp4"; do echo "file $f"; done) -c copy -


  


  When I run this, I get Unable to find a suitable output format for 'pipe:'.

  


  From other searches, my understanding is that I need to specify an output format via the -f flag, but I'm not sure how to do that given that I already have output as my -f flag value.

  


  Does anyone have any tips for this ?

  


• Recieving multiple files from ffmpeg via subprocesses.PIPE

  19 août 2014, par Per Plexi

  I am using ffmpeg to convert a video into images. These images are then processed by my Python program. Originally I used ffmpeg to first save the images to disk, then reading them one by one with Python.

  This works fine, but in an effort to speed up the program I am trying to skip the storage step and only work with the images in memory.

  I use the following ffmpeg and Python subproccesses command to pipe the output from ffmpeg to Python :

  command = "ffmpeg.exe -i ADD\\sg1-original.mp4 -r 1 -f image2pipe pipe:1"
  
  pipe = subprocess.Popen(ffmpeg-command, stdout = subprocess.PIPE, stderr = subprocess.PIPE)
  
  image = Image.new(pipe.communicate()[0])

  The image variable can then be used by my program. The problem is that if I send more than 1 image from ffmpeg all the data is stored in this variable. I need a way to separate the images. The only way I can think of is splitting on jpeg markers end of file (0xff, 0xd9). This works, but is unreliable.

  What have I missed regarding piping files with subproccesses. Is there a way to only read one file at a time from the pipeline ?

• Error setting option pix_fmt to value -1 : Pipe a mp4 video with ffmpeg

  14 août 2014, par Lewisou

  I was piping a mp4 file and always got Error setting option pix_fmt to value -1.

  I was trying to put -pix_fmt option in front of ’-i inputfile’, as in the ffmpeg output I found a message : unspecified pixel format but it seems not work

  The ffmpeg outpus is here : http://pastebin.com/8hNdLeQ2

  By the way, the ffmpeg version I was using is the latest one from git repo

  And the mp4 video clip is from a sumsung tablet.

  The command I use :
  $ cat b2.mp4 | ./ffmpeg -i pipe:0 -c:a copy a.mp4

  I also tried :

  The video is at : https://www.dropbox.com/s/oz0e51ggkbpgj0f/b2.mp4

  Anyone can tell me how to pipe this mp4 video, Thanks,

  Lewis