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• IO.copy_stream performance in ruby

  19 juillet 2016, par stiller_leser

  I am trying to continously read a file in ruby (which is growing over time and needs to be processed in a separate process). Currently I am archiving this with the following bit of code :

  r,w = IO.pipe
  
  pid = Process.spawn('ffmpeg'+ffmpeg_args, {STDIN => r, STDERR => STDOUT})
  
  Process.detach pid
  
  while true do
  
    IO.copy_stream(open(@options['filename']), w)
  
    sleep 1
  
  end

  However - while working - I can’t imagine that this is the most performant way of doing it. An alternative would be to use the following variation :

  step = 1024*4
  
  copied = 0
  
  pid = Process.spawn('ffmpeg'+ffmpeg_args, {STDIN => r, STDERR => STDOUT})
  
  Process.detach pid
  
  while true do
  
    IO.copy_stream(open(@options['filename']), w, step, copied)
  
    copied += step
  
    sleep 1
  
  end

  which would only continously copy parts of the file (the issue here being if the step should ever overreach the end of the file). Other approaches such a simple read-file led to ffmpeg failing when there was no new data. With this solution the frames are dropped if no new data is available (which is what I need).

  Is there a better way (more performant) to archive something like that ?

  EDIT :

  Using the method proposed by @RaVeN I am now using the following code :

  open(@options['filename'], 'rb') do |stream|
  
    stream.seek(0, IO::SEEK_END)
  
    queue = INotify::Notifier.new
  
    queue.watch(@options['filename'], :modify) do
  
      w.write stream.read
  
    end
  
    queue.run
  
  end

  However now ffmpeg complaints about invalid data. Is there another method than read ?

• ffmpeg forward hls stream

  7 juillet 2016, par gemisoft

  I am trying to forward HLS stream to server via RTSP. On the server, it will be transcoded to the multiple bitrate streams so a wide range of users can watch stream.

  To achieve this, I am using ffmpeg.

  1. Should I stream to my server in best quality because my server will do transcoding to lower bitrate streams ?

  2. I am using this command :

     ffmpeg -i http://vevoplaylist-live.hls.adaptive.level3.net/vevo/ch1/appleman.m3u8 -c:v libx264 -preset veryfast -maxrate 2000k -bufsize 2000k -g 60 -c:a aac -b:a 96k -ac 2 -ar 44100 -f rtsp -muxdelay 0.1 rtsp ://username:password@95.138.139.123:1935/live/myStream

  But my stream is pixelated on some moments like on the picture :
  
  How can I fix that ?

  3. Is there some better method to achieve this ?

  Here is log file from ffmpeg.
  Log file

• Hide ffmpeg's console window when running YoutubeDL in GUI application

  23 juin 2016, par Slayther

  I’m developing a basic application which can download YouTube videos. Throughout the development, I had several quirks, including issues with formats.

  I decided to use a hopefully foolproof format syntax that youtube-dl will happily download for me in almost any case.

  Part of my YoutubeDL options look like this :

  self.ydl_opts = {
  
      'format': 'bestvideo[ext=mp4]+bestaudio[ext=m4a]/best[ext=mp4]/best',
  
      'quiet': True,
  
      'progress_hooks': [self.ydl_progress],
  
      'outtmpl': None
  
  }

  The outtmpl is inserted later on when output folder is chosen by the user.

  Since I’m using this format string, youtube-dl uses ffmpeg to merge(?) the audio and video if they are downloaded separately.

  When it does that, it opens very annoying console windows that capture the focus and interrupt other things I might be doing while the videos are downloading.

  My question is, how can I prevent ffmpeg or youtube-dl from creating those console windows from appearing, aka. how can I hide them ?

  EDIT :

  I’ll provide bare bones script that reproduces the problem :

  from __future__ import unicode_literals
  
  from PyQt4 import QtGui, QtCore
  
  import youtube_dl, sys
  
  
  
  def on_progress(info):
  
      print info.get("_percent_str", "Finished")
  
  
  
  ydl_opts = {
  
      'format': 'bestvideo[ext=mp4]+bestaudio[ext=m4a]/best[ext=mp4]/best',
  
      'progress_hooks': [on_progress],
  
      'quiet': True,
  
      'outtmpl': "C:/Users/Raketa/Desktop/%(title)s.%(ext)s"
  
  }
  
  
  
  ydl = youtube_dl.YoutubeDL(ydl_opts)
  
  
  
  class DownloadThread(QtCore.QThread):
  
      def __init__(self):
  
          super(DownloadThread, self).__init__()
  
          self.start()
  
  
  
      def __del__(self):
  
          self.wait()
  
  
  
      def run(self):
  
          print "Download start"
  
          ydl.download(["https://www.youtube.com/watch?v=uy7BiiOI_No"])
  
          print "Download end"
  
  
  
  class Application(QtGui.QMainWindow):
  
      def __init__(self):
  
          super(Application, self).__init__()
  
          self.dl_thread = DownloadThread()
  
  
  
      def run(self):
  
          self.show()
  
  
  
  def main():
  
      master = QtGui.QApplication(sys.argv)
  
  
  
      app = Application()
  
      app.run()
  
  
  
      sys.exit(master.exec_())
  
  
  
  if __name__ == '__main__':
  
      main()

  2(?) consoles appear at start of each download and 1 longer lasting console appears when both video and audio are downloaded. When downloading longer videos, the last console becomes unbearable.

  Is it possible to get rid of those ?