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• Best way to pipe audio and video chunks from within python to ffmpeg

  8 mai 2016, par basilikum

  Problem

  I’m getting audio and video chunks from a third-party server and I would like to pipe those chunks to ffmpeg to create a WebM live stream according to these instructions :

  http://wiki.webmproject.org/adaptive-streaming/instructions-to-do-webm-live-streaming-via-dash

  Here they are using input from webcam and microphone but I need to use the data chunks, so the ffmpeg command would look somehow like this :

      cmd = [
  
          "ffmpeg",
  
          "-f", "flv", "-i", "video.fifo",
  
          "-f", "s16le", "-ar", "16000", "-ac", "1", "-i", "audio.fifo",
  
          "-map", "0:0",
  
          "-pix_fmt", "yuv420p",
  
          "-c:v", "libvpx-vp9",
  
          "-s", "640x480", "-keyint_min", "40", "-g", "40", "-speed", "6",
  
          "-tile-columns", "4", "-frame-parallel", "1", "-threads", "8",
  
          "-static-thresh", "0", "-max-intra-rate", "300",
  
          "-deadline", "realtime", "-lag-in-frames", "0",
  
          "-error-resilient", "1",
  
          "-b:v", "3000k",
  
          "-f", "webm_chunk",
  
          "-header", self.video_header,
  
          "-chunk_start_index", "1",
  
          "video_360_%d.chk",
  
          "-map", "1:0",
  
          "-c:a", "libvorbis",
  
          "-b:a", "16k", "-ar", "16000",
  
          "-f", "webm_chunk",
  
          "-audio_chunk_duration", "2000",
  
          "-header", self.audio_header,
  
          "-chunk_start_index", "1",
  
          "audio_171_%d.chk"
  
      ]

  As you can see, I am using a "video.fifo" and "audio.fifo" file, because I thought it would be a good idea to pipe the chunks in via a named pipe, but I can’t get it to work. Here is what I’m doing :

  p = subprocess.Popen(cmd)
  
  fa = os.open("video.fifo", os.O_WRONLY)
  
  fv = os.open("audio.fifo", os.O_WRONLY)

  So I’m starting the subprocess first, so that it opens the fifo files for reading. After that, I should be able to open them for writing but I am not. More specifically, I am able to open the first one, but not the second one. So maybe that has something to do with how ffmpeg handles its inputs if there are more than one, but I just don’t know.

  Question

  How can I either solve the problem of non openable named pipes or how can I achieve what I wanted to achieve without named pipes.

• ffmpeg command slow zoom in according to duration. (example) i define -t 120 than picture should be zoom in for two minute softly

  12 septembre 2018, par Zeeshan Sheikh

  i have a command that convert the image into video with soft zoom out effect, command is :

  ffmpeg -loop 1 -i vide.mp4 -vf "zoompan=z=’1.5-on/duration*0.2’:d=325" -t 30 output.mp4

  . now i want soft zoom in effect rather than zoom out, can somebody help to achieve result. Thanks in advance

• Revision 31039 : Le site gravatar.com fournit un nouveau moyen plus fiable de tester ...

  21 août 2009, par da@… — Log

  Le site gravatar.com fournit un nouveau moyen plus fiable de tester l’existence d’un avatar : on peut lui demander de renvoyer une erreur 404 s’il existe pas (oui ça devrait être le comportement par défaut, c’est un peu exactement à ça que servent les erreurs 404...). Dans SPIP, c’est pratique, ça se traduit par un résultat vide pour recuperer_page(), même si la page 404 a un contenu, ce qui simplifie les tests.