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• 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);
  
      }
  
  });

• How to transcode 50 H264 Streams with FFMPEG more efficient ?

  20 juin 2019, par Kevin

  i need to (Re-)Transcode 50 Live-Streams. These streams are in H264 with 720p to 1080p and bitrates up to 10M. I just want to reduce the quality and bitrate of the streams to up to 720p with max. 2M Bitrate.

  That’s what i’m doing right now :

  ffmpeg -re -i "http://domain.tld/path/file.ext" -vcodec libx264 -preset veryfast -vf scale=-2:720 -b:v 2M -maxrate 2M -bufsize 1M -acodec libfdk_aac -f flv "rtmp://127.0.0.1:1935/live/stream_xyz"

  My Server CPU (2 x Xeon E5-2630 v3) is already at 100% with just 12 streams. I will upgrade my server to 2 x Xeon Gold 5118 next month, but i don’t think, that this will give me that much more power.

  Can someone help me, to do this more efficient ?

  Would it be more efficient / cheaper to do this with GPUs ?

  Or any other ideas, to do that as efficient and cheap as possible ?

  Thanks

• How to transcode 50 H264 Streams with FFMPEG more efficient ?

  20 juin 2019, par Kevin

  i need to (Re-)Transcode 50 Live-Streams. These streams are in H264 with 720p to 1080p and bitrates up to 10M. I just want to reduce the quality and bitrate of the streams to up to 720p with max. 2M Bitrate.

  That’s what i’m doing right now :

  ffmpeg -re -i "http://domain.tld/path/file.ext" -vcodec libx264 -preset veryfast -vf scale=-2:720 -b:v 2M -maxrate 2M -bufsize 1M -acodec libfdk_aac -f flv "rtmp://127.0.0.1:1935/live/stream_xyz"

  My Server CPU (2 x Xeon E5-2630 v3) is already at 100% with just 12 streams. I will upgrade my server to 2 x Xeon Gold 5118 next month, but i don’t think, that this will give me that much more power.

  Can someone help me, to do this more efficient ?

  Would it be more efficient / cheaper to do this with GPUs ?

  Or any other ideas, to do that as efficient and cheap as possible ?

  Thanks