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• How to pipe live video frames from ffmpeg to PIL ?

  30 janvier 2017, par Ryan Martin

  I need to use ffmpeg/avconv to pipe jpg frames to a python PIL (Pillow) Image object, using gst as an intermediary*. I’ve been searching everywhere for this answer without much luck. I think I’m close - but I’m stuck. Using Python 2.7

  My ideal pipeline, launched from python, looks like this :

  1. ffmpeg/avconv (as h264 video)
  2. Piped ->
  3. gst-streamer (frames split into jpg)
  4. Piped ->
  5. Pil Image Object

  I have the first few steps under control as a single command that writes .jpgs to disk as furiously fast as the hardware will allow.

  That command looks something like this :

  command = [
  
          "ffmpeg",
  
          "-f video4linux2",
  
          "-r 30",
  
          "-video_size 1280x720",
  
          "-pixel_format 'uyvy422'",
  
          "-i /dev/video0",
  
          "-vf fps=30",
  
          "-f H264",
  
          "-vcodec libx264",
  
          "-preset ultrafast",
  
          "pipe:1 -",
  
          "|", # Pipe to GST
  
          "gst-launch-1.0 fdsrc !",
  
          "video/x-h264,framerate=30/1,stream-format=byte-stream !",
  
          "decodebin ! videorate ! video/x-raw,framerate=30/1 !",
  
          "videoconvert !",
  
          "jpegenc quality=55 !",
  
          "multifilesink location=" + Utils.live_sync_path + "live_%04d.jpg"
  
        ]

  This will successfully write frames to disk if ran with popen or os.system.

  But instead of writing frames to disk, I want to capture the output in my subprocess pipe and read the frames, as they are written, in a file-like buffer that can then be read by PIL.

  Something like this :

      import subprocess as sp
  
      import shlex
  
      import StringIO
  
  
  
      clean_cmd = shlex.split(" ".join(command))
  
      pipe = sp.Popen(clean_cmd, stdout = sp.PIPE, bufsize=10**8)
  
  
  
      while pipe:
  
  
  
          raw = pipe.stdout.read()
  
          buff = StringIO.StringIO()
  
          buff.write(raw)
  
          buff.seek(0)
  
  
  
          # Open or do something clever...
  
          im = Image.open(buff)
  
          im.show()
  
  
  
          pipe.flush()

  This code doesn’t work - I’m not even sure I can use "while pipe" in this way. I’m fairly new to using buffers and piping in this way.

  I’m not sure how I would know that an image has been written to the pipe or when to read the ’next’ image.

  Any help would be greatly appreciated in understanding how to read the images from a pipe rather than to disk.

  • This is ultimately a Raspberry Pi 3 pipeline and in order to increase my frame rates I can’t (A) read/write to/from disk or (B) use a frame by frame capture method - as opposed to running H246 video directly from the camera chip.

• How to save the stream URL chunks as a video in NodeJs

  2 octobre 2020, par Harsh Lodhi

  I'm trying to download a piece of video from the below URL using axios.

  


  https://r5---sn-gwpa-civy.googlevideo.com/videoplayback?...&range=32104-500230


  


  I'm using below code to fetch the above URL and for save the chunk to the mp4 file.

  


  axios({
        url: MY_URL`,
        method: 'GET',
        responseType: 'stream'
    }).then(function (response) {
        let buffArray = []
        response.data.on('data', (chunk) => {
            buffArray .push(chunk)
        })

        response.data.on('end', (chunk) => {
            let buff = Buffer.concat(buffArray)
            fs.writeFile('output.mp4', buff, (dt) => {
                console.log("File created");
            })
        })
    })


  


  above code is working fine and I'm able to save the video but the video is not able to play.
when I set the range in URL from &range=32104-500230 to &range=0-500230 then video is working properly. Please try to help that how can I save a video from small chunk of video stream instead of saving full video.

  


• Anomalie #4134 : Redirection problématique imposée par le formulaire joindre_documents

  18 février 2021, par Maïeul Rouquette

  Peut être lié à ce bug aléatoire https://www.mail-archive.com/spip@rezo.net/msg80645.html ?