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• How to record a video conference (e.g skype, oovoo, ...) with a program written in C#

  13 août 2014, par Matin Lotfaliee

  I want to record screen (a video conference e.g skype, oovoo, ...) with a program written in C#. I searched a lot about how to do this :

  • Here suggests Windows Media Encoder, but none of their samples work correctly on my Win7. I installed the SDK but even the links to Microsoft are somehow broken or old.
  • Here suggests creating a video stream from a series of screenshots using ffmpeg. but it is probably impossible to keep the audio,mic and screenshots synced.
  • Here suggests creating a GIF file, but it does not support audio which is important to me.
  • Here suggess using Gallio framework, but I was unable to find where the usable DLL for recording is.
  • Here seems to be a great solution but it is not free...

  Compression is not important to me because a video conference uses CPU a lot.

  Can you help me find a good and easy solution with references ?

• Merge Conference Video and Audio call output using hstack ffmpeg

  3 janvier 2020, par venkat

  having two videos and two audio files

  Input #0, matroska,webm, from 'first.mkv':
  
    Metadata:
  
      encoder         : GStreamer matroskamux version 1.8.1.1
  
      creation_time   : 2017-10-16 14:13:15
  
    Duration: 00:06:01.24, start: 3.817000, bitrate: 1547 kb/s
  
      Stream #0:0(eng): Video: vp8, yuv420p, 640x480, SAR 1:1 DAR 4:3, 16.75 tbr, 1k tbn, 1k tbc (default)
  
      Metadata:
  
        title           : Video
  
  Input #1, matroska,webm, from 'second.mkv':
  
    Metadata:
  
      encoder         : GStreamer matroskamux version 1.8.1.1
  
      creation_time   : 2017-10-16 14:13:24
  
    Duration: 00:05:49.79, start: 13.509000, bitrate: 810 kb/s
  
      Stream #1:0(eng): Video: vp8, yuv420p, 640x480, SAR 1:1 DAR 4:3, 1k tbr, 1k tbn, 1k tbc (default)
  
      Metadata:
  
        title           : Video
  
  Input #2, matroska,webm, from 'first.mka':
  
    Metadata:
  
      encoder         : GStreamer matroskamux version 1.8.1.1
  
      creation_time   : 2017-10-16 14:13:15
  
    Duration: 00:06:01.30, start: 3.786000, bitrate: 46 kb/s
  
      Stream #3:0(eng): Audio: opus, 48000 Hz, stereo, fltp (default)
  
      Metadata:
  
        title           : Audio
  
  Input #3, matroska,webm, from 'second.mka':
  
    Metadata:
  
      encoder         : GStreamer matroskamux version 1.8.1.1
  
      creation_time   : 2017-10-16 14:13:24
  
    Duration: 00:05:50.61, start: 13.498000, bitrate: 50 kb/s
  
      Stream #2:0(eng): Audio: opus, 48000 Hz, stereo, fltp (default)
  
      Metadata:
  
        title           : Audio

  above files are output of video conference call, want to merge all files together and show as side by side video.

  start time of video and audio are different, want to sync the video and audio respectively and merge the video side by side.

  Initially used the following command to merge two videos

  ffmpeg -i first.mkv -i second.mkv -filter_complex "
  
  [0:v]scale=320:240,pad=325:240,setsar=1[l];[1:v]scale=320:240,setsar=1[r];
  
  [l][r]hstack" -c:v libx264 -preset ultrafast -crf 0 merged.mp4

  After that use the following command to merge as suggested by @mulvya

  ffmpeg -ss 00:00:09.692 -i first.mkv -i second.mkv -i first.mka -i second.mka -filter_complex "[0:v]scale=320:240,pad=325:240,setsar=1[l];[1:v]scale=320:240,setsar=1[r];[l][r]hstack=shortest=1[v];[3]adelay=9712|9712[3a];[2][3a]amerge[a]" -map '[v]' -map '[a]' -c:v libx264 -preset slower -crf 0 -c:a aac -ac 2 merged.mp4

  for the -ss value taken the difference in video start time and adelay value taken the difference in audio start time

  Sample test conference files

  1. https://drive.google.com/open?id=0ByVMq5U43FGlbXpXR3JtSnFTaWM

  2. https://drive.google.com/open?id=0ByVMq5U43FGlbENVRWlTWktQb3M

  3. https://drive.google.com/open?id=0ByVMq5U43FGldndlZDNpNWxWY2M

  4. https://drive.google.com/open?id=0ByVMq5U43FGlei1oRjNKeXRZbE0

  now facing audio sync issues and second audio hearing low.

  Expected result is first video and second video merged side by side and audio should sync with merged video.

  Now I can able to get desired output using the below command

  ffmpeg -i first.mkv -i second.mkv -i first.mka -i second.mka -filter_complex "[0]scale=320:240,pad=645:240,setsar=1[l];[1]scale=320:240,setpts=PTS-STARTPTS+9.723/TB,setsar=1[1v];[l][1v]overlay=x=325[v];[3]adelay=9712|9712[1a];[2]adelay=31|31[2a];[2a][1a]amerge=inputs=2[a]" -map '[v]' -map '[a]' -c:v libx264 -preset slower -crf 0 -c:a aac -ac 2 merged.mp4

  but again facing following issues

  1. Second Video not encoded properly stuck in middle and playing.
  2. Audio Sync issues.
  3. Conversion process is slow. how can be above work done using hstack ?.

  any suggestions or help ?

• How can I broadcast a Twilio (group room) video conference ?

  2 novembre 2022, par Danish

  I have been trying different solutions/approaches for last few days and posting here to get some more options.

  



  I am planning to use Twilio's Programmable Video solution with Group room (upto 50 participants) to allow hosts/presenters to join video conference meeting. Right now I am able to setup and get started with quickstart example here

  



  Also, in parallel, I need to be able to broadcast that live meeting room through RTMP/HLS (audio+video) streaming that can be viewed (through another portal) by large user set (ideally around 10k+)

  



  Twilio support team suggested - integrating Twilio Video with Wowza using screenscrapping and ffmpeg (i.e. render the video into a (maybe virtual) screen, capture it and send to Wowza using ffmpeg.)

  



  I am new to both ffmpeg and wowza. However, I am looking to see high level solution which can be used to achieve this (with minimum hanging parts).

  



  Ideal flow i can think of is

  



  

  • Start a Twilio video conference room with actual presenters

  


  • all participants share there video and audio tracks with each other in the room - standard behavior

  


  • a new ghost-participant joins-in from stand-alone server (from wowza or SIP) and subscribes to audio-video tracks in conference.

  


  • arrange & combine those tracks into one channel and stream it as HLS

  


  • this ghost-participant will also be able to identify dominant speaker and re-arrange video tracks to show current speaker occupying bigger space (just like zoom)

  


  • and of course, this streamed video (with audio) will be one-way and viewers cannot interact. Just see be able to see the room broadcasting.

  


  



  Also/FYI
I have tried exploring few more options below (with no success)

  



  


  1. a blog here explain how can we broadcast a twilio audio
conference. At the bottom it also mention about video streaming. but, I am not getting how can we use SIP to get video stream that can be broadcasted. Also, how can I manipulate video tracks to show dominant speakers in full screen view Vs other participant in thumbnail view i.e. custom layouts.

  


  2. I also explored option of Wowza WebRTC streaming to achieve this, but it has got other technical challenges with setting up video room with multiple participants. I am going to reach out to them to see if this use-case is possible with their offering.

  


  3. I am looking for something as simple as here - dial as guest participant into video room from standalone streaming server/wowza server. And get output as single stream to broadcast.

  


  



  Any other pointers or links to solutions would be helpful.