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• Video transcoding during stream

  31 juillet 2017, par Wajahat

  I am trying to setup a testbed that will be used for experimentation, and I have deployed some VMs over Openstack and the setup looks like this currently :
  
  The far right machine is running Apache2 server and video is hosted in /var/www/html/videos folder. VNF1 and VNF2 machines are acting as intermediate routers with static routes configured to route traffic to Apache server machine.

  The client machine runs VLC player to stream video on-demand from the server over HTTP like this :

  vlc http://10.10.2.7/videos/bunny.mp4

  Now, I want to be able to do dynamic transcoding of video while it is being streamed, but I don’t want to do transcoding at server side (for experiment’s purpose the server is not in our control) neither at client side but somewhere in the middle machines (VNF1 for example) so that it is transparent to client.
  Basically, I want to implement video transcoder as a network function.

  I have found FFmpeg which I think should be able to get this done, ffmpeg-server for example allows streaming over HTTP, but I am not exactly sure how to use it for transcoding video traffic ?

• youtube-dl streaming to pipe, how to add container

  24 décembre 2017, par MetNP

  I use this command on raspberry-pi :

  youtube-dl -o- [youtubeurl] | omxplayer --no-keys pipe:0

  and it works great for 50% of youtube content. For non-working videos, omxplayer just won’t play it. It is not raspberry nor omxplayer specific problem. All players are ffmpeg based and for those videos the same problem can be achieved on any platform with ffplay or ffmpeg live transcode...

  When i download that kind of video separatelly :

  youtube-dl -o name.mp4 [url]
  
  ffplay name.mp4                   ... works OK
  
  cat name.mp4 | ffplay -           ... does NOT work (input stream not recognized well)

  Reason for this problem is well explained here. MP4 by itself is not good enough for streaming, and i want just to envelope it inside some TS or MKV or any container that will help player.

  Does someone have an idea how to do it ? Can youtube-dl be forced to do it itself, and can some middle ffmpeg command helps ?

  update : thanks to directions from Mulvya comment, it seems that all video works well with -f mp4 addition :

  youtube-dl -o- -f mp4 [youtubeurl] | omxplayer --no-keys pipe:0

  selecting specific format like -f 135+140 breaks pipe usability, and will not work except with some possible code changes. Until i reach some other problematic video content, it seems that -f mp4 solved everything.

• ffmpeg rotate, trim, and crop video

  1er novembre 2017, par 1234567

  ffmpeg rotate, trim, and crop video

  I am trying following command

  "-y", "-i", j, "-ss",15, "-t", 40
  
                      ,"-filter_complex", "transpose=1,crop=" +
  
                     40 + ":" + 20 + ":" + 100 + ":" + 100, "-c:a", "copy", "-preset", "ultrafast",out

  this command works but creates a black video

  If remove the transpose from command it works fine

  second part is I want to remove a part of video and rotate and crop that video

  for example in a video of 1 min 25 seconds and i want to remove a part from 40-50 sec I am trying this command

  "-y", "-i", j,
  
                        "-filter_complex", "transpose=1," +
  
                          "[0:v]trim=start=40:end=50,setpts=PTS-STARTPTS[b];" +
  
                          "[a][b]concat[c];[c][d]concat[out1]" +
  
                          "crop=" + 40 + ":" + 20 + ":" + 100 + ":" + 100,
  
                          "-c:a", "copy", "-preset", "ultrafast",out

  the error for this is

  too many input specified for the trim filter 

  I have referred this question for removing middle part of video
  https://superuser.com/questions/681885/how-can-i-remove-multiple-segments-from-a-video-using-ffmpeg