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• remuxing audio and videos (screen and presenter) captured at the same time does not synchronize

  22 septembre 2014, par user28163

  trying to merge a screencast with a video (without sound) and a sound steam which has been captured separately using ffmpeg using a bash command. All the stream-capture were started at the same time and all ffmpeg processes killed at the same time (pkill). But when I remux them together, the screencast and video does not match, and thus sound does not synchronize either.

  Where did I go wrong ? Any inputs appreciated from ffmpeg experts here. Thanks in advance.

  Please find the ffmpeg output as follows :

  1. The ffmpeg log of two videos muxing (http://pastebin.com/XwnDSf5i)
  2. The ffmpeg log of remuxing the sound with the side-by side video as of 1 above (cannot paste as the pastebin limit exeeded :( ).

  UPDATE :

  After checking the lenght of the screencast, I figured out that the screen capture (though started and stopped at the same time as video and sound using a bash script), is shorter in lenght by 1m54s than video and audio (former 34:22 vs later 36:16). The video was captured in h264 mp4 wrapper at -r 30. So is screen capture but lossless

  %ffmpeg -report -f x11grab -r 30 -s 1920x1080 -i :0.0 -qscale 0 -vcodec libx264 -threads 4 screen.m4v

  Could that be the reason for the delay ? Is there any way to extend the screencast against the videos ? Thanks !

• How to view the stream generated from mkvserver via ffplay ?

  18 juin 2019, par Chaitanya Bhardwaj

  I want to live stream from one source(ffmpeg) to multiple clients for which I’m using mkvserver.
  I’m able to live stream a webcam from ffmpeg(client) to mkvserver(server) as follows :

  On Server :

  nc -l  | ./server

  On Client :

  ffmpeg -f avfoundation -framerate 30 -i 0 -b 900k -f matroska -r 20 tcp://:

  To view the genereted steam on server, I used the ffplay as :

  ffplay tcp://:<port>
  
  </port>

  but I got the Connection timed out error. Please suggest a way to view the generated stream on the server via ffplay. Thanks !

• Pipe FFMPEG MPEG-DASH livestream to AWS S3

  17 août 2019, par Alexander

  So I’m currently trying to livestream the rendering of a GPU-heavy video (renders about 1fps), encode it to a 30fps MPEG-DASH livestream and output this to AWS S3 so Shaka Player can display the live rendering.

  The first issue is that the livestream keeps looping, it doesn’t stop after the rendering for loop is done.

  I use a python script to pipe the output of the rendering to FFMPEG, and pipe the output of FFMPEG to the aws s3 cli like this :

  p1 = Popen(['ffmpeg', '-y', '-hwaccel', 'cuvid', '-f', 'image2pipe', '-r', '24', '-i', '-', '-c:v', 'h264_nvenc', '-b:v', '5M', '-f', 'dash', '-movflags', 'frag_keyframe+empty_moov', '-'], stdin=PIPE)#, shell=True) #'-method', 'PUT', 'https://example.s3.amazonaws.com/test1/test1.mpd'], stdin=PIPE)
  
  
  
  p2 = Popen(['aws', 's3', 'cp', '-', 's3://example/test1/test1.mpd'], stdin=p1.stdout)
  
  
  
  
  
  #The following commented aws s3 sync command uploads successfully to S3
  
  #but the issue here is that it stops after the syncing is done and its hacky
  
  #p1 = Popen(['ffmpeg', '-y', '-vsync', '0', '-hwaccel', 'cuvid', '-f', 'image2pipe', '-r', '24', '-i', '-', '-c:v', 'h264_nvenc', '-b:v', '5M', '-f', 'dash', '-movflags', 'frag_keyframe+empty_moov', 'test2.mpd'], stdin=PIPE)#, shell=True) #'-method', 'PUT', 'https://teststream.s3.amazonaws.com/test1/test1.mpd'], stdin=PIPE)
  
  #p2 = Popen(['aws', 's3', 'sync', '.', 's3://teststream/test1', '--exclude', '"*"', '--include', '"*.m4s"', '--include', '"*.mpd"'], stdin=PIPE)
  
  
  
  #pseudocode
  
  for ci,(content,contentName) in enumerate(content_loader):
  
      im = renderframe(content)
  
      im.save(p1.stdin, 'PNG')
  
  
  
  p1.stdin.close()
  
  p1.wait()
  
  p2.stdin.close()
  
  p2.wait()