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• Can someone help me to install the netflix's VMAF library in Ubuntu

  20 février 2023, par peter12

  First of all, I have to say that I am not very experienced in ubuntu.
I would like to install this library to use with FFMPEG.

  



  I am following these steps, but I can manage to install it well...

  



  https://github.com/Netflix/vmaf/blob/master/resource/doc/VMAF_Python_library.md

  



  Could someone tell me what are the exact steps (commands) that I have to follow.

  



  On the other hand, someone knows if there are other metrics that can ffmpeg calculates directly (apart from PSNR or SSIM) ?

  



  Many thanks

  


• ffmpeg and VLC input rtp

  19 juillet 2014, par ILoveSelfStudiyn

  I want to stream screen desktop through ffmpeg library in RTP and take this stream in VLC player.

  So, I have done next steps :

  1. Load static ffmpeg and run RTP strem of my desktop throught next command :

  ffmpeg -f gdigrab -framerate 30 -i desktop -q 0 -an -f rtp
  rtp ://127.0.0.1:2304 > 1.sdp

  stream successfully works.
  https://dl.dropboxusercontent.com/u/8262546/HjbKq%5B1%5D.jpg

  When I connect to this stream throught ffplay 1.sdp - everything is ok.

  2.When I connect to this stream(rtp ://127.0.0.1:2304) through VLC player, I receive next error :

  SDP required : A description in SDP format is required to receive the
  RTP stream. Note that rtp :// URIs cannot work with dynamic RTP payload
  format (96).

  According with error I open 1.sdp file which generated by ffmpeg, but this don’t resolve problem.

  1.sdp :

  v=0

  o=- 0 0 IN IP4 127.0.0.1

  s=No Name

  c=IN IP4 127.0.0.1

  t=0 0

  a=tool:libavformat 55.48.101

  m=video 2304 RTP/AVP 96

  b=AS:200

  a=rtpmap:96 MP4V-ES/90000

  a=fmtp:96 profile-level-id=1

  Dear friends, how can I open RTP stream which generates ffmpeg through VLC player ?
  It can be rtsp stream too, I tried it, but this don’t resolve problem.
  Thanks a lot !

• Why is ffmpeg's hstack so much slower than overlay and pad ?

  27 janvier 2021, par cgenco

  I'm using ffmpeg to stitch together two videos of people chatting into a video with each of them side-by-side, like this :

  


  

  


  Here's the command I'm currently using to get this done, which runs at 2.5x on my 13" M1 MacBook Pro :

  


  ffmpeg -y -i left.mp4 -i right.mp4 -filter_complex "
  [0:v] crop=w=in_w/2 [croppedLeft];
  [1:v][1:v] overlay=x=overlay_w/4 [shiftedRight];
  [shiftedRight][croppedLeft] overlay [vout];
  [0:a][1:a] amix [aout]
" -map "[vout]" -map "[aout]" -ac 2 out.mp4


  


  This command crops the left video to half of its original width (cropping so the video is centered), then shifts the right video a quarter of its width to the right, then overlays the left video on the left half of the output merged with the shifted right video.

  


  One day on my weekly fun-time read-through the FFmpeg filters documentation I stumbled on a filter named hstack, which is described as being "faster than using overlay and pad filter to create same output."

  


  My ex wife can affirm that there are few higher priorities in my life than going faster, so I altered my ffmpeg script to use hstack instead of two overlays :

  


  ffmpeg -y -i left.mp4 -i right.mp4 -filter_complex "
  [0:v] crop=w=in_w/2 [croppedLeft];
  [1:v] crop=w=in_w/2 [croppedRight];
  [croppedLeft][croppedRight] vstack [vout];
  [0:a][1:a] amix [aout]
" -map "[vout]" -map "[aout]" -ac 2 out.mp4


  


  ...but that command runs painfully slowly, like 0.1x. It takes multiple minutes to render a single second.

  


  So uhhh what's going on here ? Why is hstack taking so long when it's supposed to be faster ?

  


  I've tried this on both the M1 native build from OSXExperts (version N-99816-g3da35b7) and the standard ffmpeg from brew and hstack is just as slow on each.