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• ffmpeg nvenc_h264 streaming uhd2160 rawvideo. Youtube buffering

  23 janvier 2019, par Alex Deroza

  I use this batch file for starting my stream :

  echo starting transocding from native uhd2160 to fhd format.. Host: YouTube
  
  ffmpeg ^
  
      -loglevel -8 ^
  
      -f rawvideo -s:v 1920x1080 -r 60 -pix_fmt nv12 ^
  
      -f dshow -i video="Game Capture 4K60 Pro Video 01":audio="Game Capture 4K60 Pro Audio 01" ^
  
      -c:v h264_nvenc ^
  
      -level:v 4.2 ^
  
      -profile:v high ^
  
      -preset:v hq ^
  
      -b:v 8.8M ^
  
      -color_range 2 ^
  
      -colorspace bt709 ^
  
      -bf 0 ^
  
      -g 60 ^
  
      -2pass 1 ^
  
      -rc:v cbr ^
  
      -coder cabac ^
  
      -acodec aac ^
  
      -ab 128k ^
  
      -movflags +faststart ^
  
      -f flv rtmp://a.rtmp.youtube.com/live2/xxxx-xxxx-xxxx-xxxx && pause

  Stream on YouTube starts fine, and plays with good quality. But stream stops after when "Buffer Health" emptied. And in this situation Youtube says that "Video output low", "YouTube is not receiving enough video to maintain smooth streaming. As such, viewers will experience buffering."

  I can’t understand why it happens. Because I’ve a good ISP, and over 30 mbps inet to YT services within 90ms latency to them.

  YouTube is not receiving enough video to maintain smooth streaming. As
  such, viewers will experience buffering.

  Your encoder is sending data faster than realtime (multipleseconds of
  video each second). You must rate limit your livevideo upload to
  approximately 1 second of video each second.

  The stream’s current bitrate (5730.00 Kbps) is lower than the
  recommended bitrate. We recommend that you use a stream bitrate of
  4500 Kbps.

• How to use ffmpeg to encode multi-channel video ?

  13 juillet 2018, par Leo

  Like nomral video have RGB/YUV, 3 channels.
  Is it possible use the existing video convertor to encode more than 3 channel video ? (e.g. given 5 folders of the same number and resolution pictures, generate a 5-channel video from them)
  I not need to playback the 5-channel video, which is impossible for 3-channel display. I just need to encode it and then decode it back to images. Actually what I am looking for is not a playable video format, I am trying to compressing several similar video content into one file, so that hopefully they can share the motion vectors and save more space.

  Dose any existing video codec support this manipulation ? Or how should I rewrite some part of the exsiting video codec(some light weight implementation of H264) to support it ?

• Convert youtube video files with ffmpeg to a format that can be playable on ios devices

  26 décembre 2018, par Amin

  I’ve created a telegram robot that downloads YouTube files and sends them to the user. Since most of our users use ios devices, Our first priority is ios.
  Videos files play on Windows and Android but not broadcast on ios.
  I convert format with ffmpeg after download from youtube :

  ffmpeg -i input.mp4 -strict -2 -vcodec mpeg4 output.mp4

  But in addition to prolonging the processing time, the file size increases and eventually the file will not run again in ios.