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• Node.js asynchronous video conversion slow

  9 décembre 2016, par lukstei

  I wrote a little website/service, which can download a video from a website (currently Youtube) and converts it on the fly to an mp3 file and sends this file back as the response.

  For example, you when you request http://localhost:8000/v=http ://www.youtube.com/watch?v=HhoewflkQu0, then it will download this video and response the audio layer encoded in MP3.

  This all works very well, my problem is that this is very slow and I can’t figure out why.

  ---

  Simplified the script behaves like this :

  Download the video and write it to the stdin of ffmpeg, and the stdout goes to the response.
  Video (MP4, FLV) -> FFMPEG -> MP3

  I used curl to figure out how fast the script is :

  $ curl http://localhost:8000/v=http://www.youtube.com/watch?v=HhoewflkQu0

  I get only about 5-10k.

  So why is this so slow ?

  1. The server, from which I am downloading the video is slow.
  2. The conversion is slow (because of a slow CPU).
  3. The data transfer between node.js -> FFMPEG is slow.

  I tried to download the video in a normal download manager, and i got about 320k, which is my normal download speed, so the first point isn’t the bottleneck.

  To point 2 and 3, I tried to write a local file to the stdin, and I got about 600k so that isn’t it either.

  So why is my script so slow, and what can I do to make it faster ?

  https://gist.github.com/1304637

  Thanks in advance.

• When using subprocess passthrough is not accepting both inputs

  30 janvier 2021, par Baraque Obahamas

  Im trying to have two subprocesses pipe into one and output via the passthrough. My goal is to make it possible to download 2 files (one video and one audio) and combine them with ffmpeg.

  


  header('Content-Description: File Transfer');
header('Cache-Control: must-revalidate');
header('Pragma: public');
header("Content-Disposition: attachment; filename=\"ok.mp4\"");
header("Content-Type: application/octet-stream");

$cmd = "<(youtube-dl -f bestvideo[ext=mp4] --no-part --no-cache-dir --no-warnings --no-progress -o - https://www.youtube.com/watch?v=6Dh-RL__uN4) <(youtube-dl -f bestaudio[ext=m4a] --no-part --no-cache-dir --no-warnings --no-progress -o - https://www.youtube.com/watch?v=6Dh-RL__uN4) | ffmpeg -i - -i pipe:3 -movflags frag_keyframe+empty_moov+faststart -frag_duration 3600 -c:v copy -c:a copy -f mp4 -";

$cmd = passthru($cmd, $status);


  


  My error is : -bash : /dev/fd/63 : Permission denied

  


• Increasing speed of a video in C# ?

  13 décembre 2017, par alan samuel

  I am trying to increase the speed of a video using NReco.VideoConverter.FFMpegConverter

  Here is what I have tried.

    var ffMpeg = new NReco.VideoConverter.FFMpegConverter();
  
    string inputfile = @"C:\Users\Alan\Desktop\Video.flv";
  
    string outputfile = @"C:\Users\Alan\Desktop\converted.mp4";
  
  
  
  
  
    ConvertSettings convertSettings = new ConvertSettings
  
          {
  
              MaxDuration = 10,
  
              VideoFrameRate = 12
  
              //VideoFrameCount = 10
  
  
  
          };
  
  
  
  ffMpeg.ConvertMedia(inputfile,Format.flv, outputfile,Format.mp4,convertSettings);

  What I want is like a video with an increased playback like in this example - https://www.youtube.com/watch?v=6tQ1ewhGiwk

  This is what I am basically trying to do.