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• Extracting a clip from a video with low fps

  1er juin 2016, par superMind

  I want to extract a clip from a video( downloaded from [1]) (which has low frame rate) by specifying the start and end time. In order to do that, I use the following command :

  ffmpeg -i example.webm -ss 116.38 -to 126.38 clip.mpg

  however, I get the following error :

  ---

  ffmpeg version N-80026-g936751b Copyright (c) 2000-2016 the FFmpeg developers
  
  built with gcc 4.8 (Ubuntu 4.8.4-2ubuntu1~14.04.3)
  
  configuration: --extra-libs=-ldl --prefix=/opt/ffmpeg --mandir=/usr/share/man --enable-avresample --disable-debug --enable-nonfree --enable-gpl --enable-version3 --enable-libopencore-amrnb --enable-libopencore-amrwb --disable-decoder=amrnb --disable-decoder=amrwb --enable-libpulse --enable-libfreetype --enable-gnutls --enable-libx264 --enable-libx265 --enable-libfdk-aac --enable-libvorbis --enable-libmp3lame --enable-libopus --enable-libvpx --enable-libspeex --enable-libass --enable-avisynth --enable-libsoxr --enable-libxvid --enable-libvidstab
  
  libavutil 55. 24.100 / 55. 24.100
  
  libavcodec 57. 42.100 / 57. 42.100
  
  libavformat 57. 36.100 / 57. 36.100
  
  libavdevice 57. 0.101 / 57. 0.101
  
  libavfilter 6. 45.100 / 6. 45.100
  
  libavresample 3. 0. 0 / 3. 0. 0
  
  libswscale 4. 1.100 / 4. 1.100
  
  libswresample 2. 0.101 / 2. 0.101
  
  libpostproc 54. 0.100 / 54. 0.100
  
  Input #0, matroska,webm, from 'example.webm':
  
  Metadata:
  
  encoder : Google
  
  Duration: 00:04:22.29, start: 0.000000, bitrate: 207 kb/s
  
  Stream #0:0: Video: vp8, yuv420p, 630x360, SAR 1:1 DAR 7:4, 6 fps, 6 tbr, 1k tbn (default)
  
  Stream #0:1: Audio: vorbis, 44100 Hz, stereo, fltp (default)
  
  [mpeg1video @ 0x252f200] MPEG1/2 does not support 5/1 fps
  
  Output #0, mpeg, to 'clip.mpg':
  
  Metadata:
  
  encoder : Google
  
  Stream #0:0: Unknown: none, SAR 1:1 DAR 0:0 (default)
  
  Metadata:
  
  encoder : Lavc57.42.100 mpeg1video
  
  Stream #0:1: Unknown: none (default)
  
  Metadata:
  
  encoder : Lavc57.42.100 mp2
  
  Stream mapping:
  
  Stream #0:0 -> #0:0 (vp8 (native) -> mpeg1video (native))
  
  Stream #0:1 -> #0:1 (vorbis (native) -> mp2 (native))
  
  Error while opening encoder for output stream #0:0 - maybe incorrect parameters such as bit_rate, rate, width or height
  
  -----------------------------------------------------

  I tried by adding -r 20 to the above command. It works in this case but not sure this is correct way to do it.
  I was wondering how can I extract the clip from this video given start time and endtime ? what are parameters should I use ? or what is correct way to do it ?

  Thanks.

  [1]https://www.youtube.com/watch?v=Yc52pGHr0xc

• How to use ffmpeg to encode isolated motion vectors (using codecview)

  22 juillet 2021, par Temmeh

  I have been successfully using this command to superimpose MPEG motion vectors onto a video :

  


  ffmpeg -v error -flags2 +export_mvs -i input.mp4 -vf codecview=mv=pf+bf+bb -y output.mp4

  


  Now I would like to be able to export an h264 mp4 of just the motion vector arrows, like in this example, without the original video layered underneath. I checked the codecview documentation and and did not find a flag or option to do this.

  


  Any help is appreciated !

  


• FFmpeg metadata tags for YouTube 3D side-by-side movies

  17 février 2021, par Some1Else

  YouTube requires specific metadata tags for 3D Side-By-Side format movies. If the tag is not there then YouTube does not give the anaglyph playback options for the end user.

  



  Their "help" is here
https://support.google.com/youtube/answer/7278886?hl=en-GB

  



  I am trying to get FFmpeg to add the MP4 tag when building my movie.

  



  Code that works now for a series of PNG files into a MP4.

  



  "ffmpeg.exe" -framerate 60 -i "VID%05d.PNG" -c:v libx264 -preset:v veryslow -profile:v high -crf 15 -s 1280x720 -pix_fmt yuvj420p -an -y "OUTPUT.MP4"


  



  But when I add the tag from the YouTube help page

  



  "ffmpeg.exe" -framerate 60 -i "VID%05d.PNG" -c:v libx264 -preset:v veryslow -profile:v high -crf 15 -s 1280x720 -pix_fmt yuvj420p -an -y -x264opts "frame-packing=3:frame-packing-interpret=1:frame-packing-quincunx=0:frame-packing-grid=0,0,0,0" "OUTPUT.MP4"


  



  I get this error from FFmpeg

  



  [libx264 @ 0000000002a8c3a0] bad option 'frame-packing-interpret': '1'


  



  This page (ignore the proselytising)

  



  http://www.pantherdynamics.yolasite.com/panther-dynamics-blog/uploading-3dsbs-content-to-youtube

  



  says you only need to use this tag

  



  -x264opts frame-packing=3


  



  Using that does make FFmpeg finish correctly, but the SBS is still ignored by YouTube

  



  The YouTube engineer blog post here

  



  https://youtube-eng.googleblog.com/2011/09/getting-3d-content-on-youtube_8.html

  



  links to an older supposed 3D movie that also does not give 3D options any more.

  



  https://www.youtube.com/watch?v=ubRHSg5daMs

  



  So maybe even YouTube's own 3D movies are crippled ?

  



  What am I doing wrong ? Any FFmpeg gurus able to help ?