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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 ?

• Download youtube video duration using youtube-dl PHP and ffmpeg

  20 juillet 2016, par user3285828

  Is there any more efficient way to download youtube videos at a specific start and end time using youtube-dl and ffmpeg in PHP.

  I currently have this, which does work, it first downloads the whole video to an mp3 file, and then crops that file to the range I set using ffmpeg, but when I only want 30 seconds or so of a 20 minute video, waiting for the full video to download doesn’t seem the best way to do it.

  <?php
  
  require __DIR__ . '/vendor/autoload.php';
  
  
  
  use YoutubeDl\YoutubeDl;
  
  
  
  $dl = new YoutubeDl([
  
      'extract-audio' => true,
  
      'audio-format' => 'mp3',
  
      'audio-quality' => 0, // best
  
      'output' => 'videoname.%(ext)s',
  
  ]);
  
  $dl->setDownloadPath('C:\youtubevideos');
  
  $video = $dl->download('https://www.youtube.com/watch?v=oDAw7vW7H0c');
  
  
  
  $start = 60; // Start 60 seconds in to the video
  
  $duration = 30; // Get 30 seconds after $start
  
  $fullVideo = "C:\youtubevideos\videoname.mp3";
  
  $shortVideo = "C:\youtubevideos\short\shortversion.mp3"; // create 30 seconds
  
  exec("ffmpeg -ss $start -i $fullVideo -t $duration -c copy $shortVideo");
  
  exec("DEL $fullVideo");

  I am using youtube dl PHP https://github.com/norkunas/youtube-dl-php

• Wowza RTMP to RTSP

  3 août 2016, par Nmas

  We’re using a Raspicam to stream live video to a client using Wowza Streaming Engine. We use FFMPEG to encode and send to Wowza and we can succesfully watch the RTMP stream using JWPlayer. This is the FFMPEG command used :

  ffmpeg -t 0 -s 320x240 -f video4linux2 -i /dev/video0 -b:v 250k -tune zerolatency -preset ultrafast -f flv -r 15 rtmp://wowzaaddress:1935/live/live

  To be able to watch the stream on mobile devices we want to use RTSP or HLS which Wowza provides links to, however when we use those links (provided on the Test Player) nothing happens and we can’t even open them to test for example in VLC. We have already added the extra ports on our web server to see if that was the problem and still didn’t work.
  Does anybody know what the problem is or what could we be doing wrong ?