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• Scaling nginx-rtmp livestreaming with ffmpeg transcoding

  31 mars 2020, par hoodsy

  I currently have a functional livestreaming setup using the prolific nginx-rtmp library, and I’m using ffmpeg to provide various resolutions of my stream.

  The only problem is, ffmpeg with only 2 outputs eats up 50% of my CPU. I’d like to be able to support up to 20 streamers at once – with the current demand, that would mean I need 10x the CPU power that I currently have !

  How can I scale my transcoding setup with nginx-rtmp and ffmpeg ?

  rtmp {
  
  server {
  
      listen 1935;
  
  
  
      application src {
  
          live on;
  
          exec_push ffmpeg -i rtmp://localhost/src/$name
  
              -c:v copy -preset:v ultrafast -b:v 512K -c:a copy -tune zerolatency -f flv rtmp://localhost/hls/$name_hi
  
              -c:v libx264 -preset:v ultrafast -s 852x480 -b:v 128K -c:a copy -tune zerolatency -f flv rtmp://localhost/hls/$name_low;
  
  
  
              # -c:v libx264 -s 852x480 -b:v 128K -c:a copy -tune zerolatency -f flv rtmp://localhost/hls/$name_low;
  
              # -c:v libx264 -s 1280x720 -b:v 256k -c:a copy -tune zerolatency -f flv rtmp://localhost/hls/$name_mid;
  
      }
  
  
  
      application hls {
  
          live on;
  
          hls on;
  
          hls_path /tmp/hls;
  
  
  
          # hls_fragment 1s;
  
          # hls_playlist_length 4s;
  
          hls_fragment 4s;
  
          hls_playlist_length 12s;
  
          hls_nested on;
  
          hls_variant _low BANDWIDTH=160000;
  
          # hls_variant _mid BANDWIDTH=320000;
  
          hls_variant _hi  BANDWIDTH=640000;
  
      }
  
  }

  }

• Gstreamer : Hauppauge HD PVR and Multi-video file output

  7 juin 2014, par user3716978

  I have very specific requirements for a Gstreamer pipeline that I can’t seem to create. I’m running Linux Mint Mate 14 (Nadia).

  I have an HD PVR, which records in MPEG TS. It presents, as its interface, a V4L2 device at /dev/video0. What I need is to somehow have it output the captured video to multiple files. That is, like dvgrab’s autosplit, it would output, say, 1800 frames, then create a new output file, then capture another 1800, and on and on.

  I’ve tried numerous methods. First, using multifilesink with the keyframe next-file option does what I want, but it doesn’t seem to add stream headers to the segment files, so that they cannot play properly and/or are missing their initial keyframe.

  I’ve tried limiting each individual capture length using num-buffers, and just restarting the capture after the previous one ends. This works for maybe 30 or 40 files but all the switching on and off eventually locks up the HD PVR, and it has to be power-cycled.

  I could also have it dump images to the disk and work with the individual frames, but this is very slow with MPEG TS since it has to demux, decode, and reencode every frame. It eats up 100% cpu and drops about 60% of the frames on my computer.

  ffmpeg doesn’t work, because the HD PVR driver doesn’t support ioctl. I can’t seem to get mencoder to stream it this way either, but maybe it’s possible ?

  What I need is to :

  • Have a single capture stream, to avoid pissing off the HD PVR
  • Have it split the stream into multiple files which can be individually analyzed
  • Have those multiple files be valid videos
  • Not eat up 100% of my CPU (although high utilization is ok, it needs to run at full speed). Since the stream is 1920x1080x60fps, anything to do with reencoding won’t work. It pretty much needs to be a stream copy.

  Thank you

• From time to time ffmpeg makes my computer unable to restart

  6 juin 2022, par principal-ideal-domain

  I'm doing very time consuming ffmpeg video editing. That's why I put my commands into a .bat file and run them over night. Usually that works fine but from time to time when I look at the next moring a see an error message of this kind :

  


  

  


  From that state on I didn't find any good way to close the console. When I press the x in the top right corner, it freezes. When I try to kill it using the task manager nothing happens. Even explorer.exe can't be closed using the task manager. A shutdown won't do anything. During the last month I had this problem about three times and the only way I could close it was to long press the power button of the computer until it was turned off this hard way.

  


  Any ideas what to in such situations ? Or even better : Any ideas how to prevent those situations ? What is the reason for the error ? Do you understand the message ? By the way, when the computer is started again then at the next morining and I run the same bat file again everything works fine. So the same error does not repeat and the video is edited nicely.

  


  Edit : Now, about one week after posting this question the problem occurred many more times. It is very annoying. I guess it has to do with the external hard drive connected by USB. Sometimes it randomly interrupts the connection. That might be the reason for the behavior. However that be, I want to learn a solution how to deal with this in future. I don't want to always push the reset button of my computer. I want a proper way to shut it down.