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• Processing Camera stream in Opencv, pushing it over RTMP (NGINX RTMP Module) using FFMPEG

  19 avril 2016, par Asymptote

  Output video :
  https://youtu.be/VxfoBQjoY6E

  Explanation :

  I want to : Process camera stream in Opencv and push it over to RTMP server. I already have NGINX (RTMP module) set up and I have tested streaming videos with both RTMP (Flash Player) and HLS.

  I am reading the frames in a loop and using ’subprocess’ in python to execute ffmpeg command. Here’s the command I am using :

  command = [ffmpeg,
  
      '-y',
  
      '-f', 'rawvideo',
  
      '-vcodec','rawvideo',
  
      '-pix_fmt', 'bgr24',
  
      '-s', dimension,
  
      '-i', '-',
  
      '-c:v', 'libx264',
  
      '-pix_fmt', 'yuv420p',
  
      '-preset', 'ultrafast',
  
      '-f', 'flv',
  
      'rtmp://10.10.10.80/live/mystream']
  
  
  
  
  
  import subprocess as sp
  
  ...
  
  proc = sp.Popen(command, stdin=sp.PIPE,shell=False)
  
  ...
  
  proc.stdin.write(frame.tostring()) #frame is read using opencv

  Problem :

  I can see the stream fine but it freezes and resumes frequently. Here’s the output of FFMPEG terminal log :

  Stream mapping:
  
    Stream #0:0 -> #0:0 (rawvideo (native) -> h264 (libx264))
  
  frame=  117 fps= 16 q=22.0 size=     344kB time=00:00:04.04 bitrate= 697.8kbits/s speed=0.543x   

  It mentions speed at the end. I believe it should be close to 1x. I am not sure how to achieve that.

  And I am on the same network as server, I can post my python code if required. Need some ffmpeg guru to give me some advise.

  EDIT

  My input fps is actually 3.
  With '-use_wallclock_as_timestamps', '1' I can see in the log that speed is close to 1x.
  But HLS is not streaming live there’s 2 min delay, it halts and . Chris’s advise partially worked. I am not sure where exactly is the problem, I am starting to believe it has something to do with nginx-rtmp module.

  Here’s the final output, on left it’s flash and on right it’s hls. I am showing the ffmpeg options at the end.
  https://youtu.be/jsm6XNFOUE4

• Processing Camera stream in Opencv, pushing it over RTMP (NGINX RTMP Module) using FFMPEG

  12 août 2019, par Asymptote

  Output video :
  https://youtu.be/VxfoBQjoY6E

  Explanation :

  I want to : Process camera stream in Opencv and push it over to RTMP server. I already have NGINX (RTMP module) set up and I have tested streaming videos with both RTMP (Flash Player) and HLS.

  I am reading the frames in a loop and using ’subprocess’ in python to execute ffmpeg command. Here’s the command I am using :

  command = [ffmpeg,
  
      '-y',
  
      '-f', 'rawvideo',
  
      '-vcodec','rawvideo',
  
      '-pix_fmt', 'bgr24',
  
      '-s', dimension,
  
      '-i', '-',
  
      '-c:v', 'libx264',
  
      '-pix_fmt', 'yuv420p',
  
      '-preset', 'ultrafast',
  
      '-f', 'flv',
  
      'rtmp://10.10.10.80/live/mystream']
  
  
  
  
  
  import subprocess as sp
  
  ...
  
  proc = sp.Popen(command, stdin=sp.PIPE,shell=False)
  
  ...
  
  proc.stdin.write(frame.tostring()) #frame is read using opencv

  Problem :

  I can see the stream fine but it freezes and resumes frequently. Here’s the output of FFMPEG terminal log :

  Stream mapping:
  
    Stream #0:0 -> #0:0 (rawvideo (native) -> h264 (libx264))
  
  frame=  117 fps= 16 q=22.0 size=     344kB time=00:00:04.04 bitrate= 697.8kbits/s speed=0.543x   

  It mentions speed at the end. I believe it should be close to 1x. I am not sure how to achieve that.

  And I am on the same network as server, I can post my python code if required. Need some ffmpeg guru to give me some advise.

  EDIT

  My input fps is actually 3.
  With '-use_wallclock_as_timestamps', '1' I can see in the log that speed is close to 1x.
  But HLS is not streaming live there’s 2 min delay, it halts and . Chris’s advise partially worked. I am not sure where exactly is the problem, I am starting to believe it has something to do with nginx-rtmp module.

  Here’s the final output, on left it’s flash and on right it’s hls. I am showing the ffmpeg options at the end.
  https://youtu.be/jsm6XNFOUE4

• Can you think of a reason why windows might not enable audio if noone is logged in ?

  3 juillet 2017, par Caius Jard

  I’m having a bizarre problem with some virtual servers created to record podcasts. They run on amazon AWS as windows server 2012 instances and a small c# app tells FFMPEG to do the heavy lifting of capturing from the virtual screen and reading from the virtual sound card (Virtual Audio Cable : https://en.wikipedia.org/wiki/Virtual_Audio_Cable) via DirectShow filters

  The problem I have is if I leave the machine to do its stuff unattended, the recordings are sometimes silent. If I log in via VNC and watch it doing its stuff the audio is recorded just fine. All other aspects of the test op are the same, and the virtual machine is shut down between successive recordings so each one should theoretically be a clean slate. The app runs under a logged in session (hence the use of VNC rather than RDP)

  I’m now wondering if there is some optimisation of the windows sound engine whereby it doesn’t bother playing audio if it thinks noone is listening. The confusing thing to me is that not every virtual machine suffers these problems ; some of them record fine (and they’re all created from the same seed virtual hard disk image) in unattended mode

  I’m asking this question with the aim of getting together a list of things I can check/look into/debug.. I don’t have much knowledge of how MME/DirectSound/WASAPI work internally...