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• No data written to stdin or stderr from ffmpeg

  13 décembre 2017, par Mikkel Bachmann

  I have a dummy client that is suppose to simulate a video recorder, on this client i want to simulate a video stream ; I have gotten so far that i can create a video from bitmap images that i create in code.

  The dummy client is a nodejs application running on an Raspberry Pi 3 with the latest version of raspian lite.

  In order to use the video I have created, I need to get ffmpeg to dump the video to pipe:1. The problem is that I need the -f rawvideo as a input parameter, else ffmpeg can’t understand my video, but when i have that parameter set ffmpeg refuses to write anything to stdio

  ffmpeg is running with these parameters

  ffmpeg -r 15 -f rawvideo -s 3840x2160 -pixel_format rgba -i pipe:0 -r 15 -vcodec h264 pipe:1

  Can anybody help with a solution to my problem ?

  —Edit

  Maybe i sould explain a bit more.
  The system i am creating is to be set up in a way, where instead of my stream server ask the video recorder for a video stream, it will be the recorder that tells the server that there is a stream.

• ffmpeg streaming video website — converting on the fly vs. hosting multiple formats

  19 avril 2014, par user1883050

  The setup : A website that streams uploaded videos using ffmpeg on the backend. Different video formats are served based on the needs of the client-device.

  My understanding is that some websites keep the same video in multiple formats, while others convert the non-HTML5 video (say) into HTML5 video on the fly if the client-device calls for HTML5 video.

  Why do one over the other ?

• Node.js Live Streaming : Avoid buffering

  27 octobre 2012, par Shirish Kamath

  I've written a small nodeJS server that outputs system audio captured by ffmpeg on Windows (using DirectShow) to the browser as a streaming MP3 file. The audio needs to be as live as possible, with minimum/no buffering, and a "skipping" effect in the audio is perfectly acceptable.

  When I play the audio in Chrome using the HTML5 audio tag, there's a delay of about 8-10 secs over a low-latency LAN connection. I suspected this to be a client-side buffer, and used a Flash MP3 player on the client-side, which brought down the delay to 2-3 secs.

  Now, the buffering seems to taking place on the server-side. The documentation for NodeJS's response.write mentions that the data is written kernel buffers. How do I go about avoiding any buffering altogether or at least getting around it, so that the client always gets the latest audio data ? Strategies for handling 'drain' events to always push live data ?

  On the request object, I've used setNoDelay(true) to avoid the use of Nagle's algorithm. Following is a snippet of how data is written when the spawned ffmpeg process emits data.

  var clients = []; //List of client connections currently being served
  
  ffmpeg.stdout.on('data', function(data) {
  
      for(var i = 0; i < clients.length; i++){
  
          clients[i].res.write(data);
  
      }
  
  });