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  • Slowing down 960 fps video with ffmpeg (setpts is not working)

    7 novembre 2016, par haridsv

    I am trying to slow down a video recorded on an Android phone at 960fps. I found a lot of previous posts and blogs that all basically say the same thing, that you need to change the "presentation timestamp" (pts). I also found the official documentation that is saying the same thing. The command-line basically looks like this :

    ffmpeg -i input.mp4 -filter:v "setpts=4*PTS" -r 30 -y output.mp4

    I copied the video file using Android Filter Transfer and when I use the above command-line, it works to slow it down, but the resulting output is choppy. The output of the ffmpeg also indicates that it is duplicating the frames :

    frame=  687 fps=103 q=-1.0 Lsize=    4454kB time=00:00:22.80 bitrate=1600.1kbits/s dup=515 drop=0 speed=3.42x

    Running ffprobe on the file shows this :

    ffprobe version 3.1.1 Copyright (c) 2007-2016 the FFmpeg developers
    
  built with Apple LLVM version 7.3.0 (clang-703.0.31)
    
  configuration: --prefix=/usr/local/Cellar/ffmpeg/3.1.1 --enable-shared --enable-pthreads --enable-gpl --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-lda
    
  libavutil      55. 28.100 / 55. 28.100
    
  libavcodec     57. 48.101 / 57. 48.101
    
  libavformat    57. 41.100 / 57. 41.100
    
  libavdevice    57.  0.101 / 57.  0.101
    
  libavfilter     6. 47.100 /  6. 47.100
    
  libavresample   3.  0.  0 /  3.  0.  0
    
  libswscale      4.  1.100 /  4.  1.100
    
  libswresample   2.  1.100 /  2.  1.100
    
  libpostproc    54.  0.100 / 54.  0.100
    
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'VID_20161030_213810.mp4':
    
  Metadata:
    
    major_brand     : mp42
    
    minor_version   : 0
    
    compatible_brands: isommp42
    
    creation_time   : 2016-10-30 16:08:14
    
    location        : +17.3874+078.3395/
    
    location-eng    : +17.3874+078.3395/
    
    com.android.version: 6.0.1
    
    com.android.capture.fps: 120.000000
    
  Duration: 00:00:05.73, start: 0.000000, bitrate: 14991 kb/s
    
    Stream #0:0(eng): Video: h264 (Baseline) (avc1 / 0x31637661), yuv420p, 1280x720, 13859 kb/s, SAR 1:1 DAR 16:9, 30 fps, 30 tbr, 90k tbn, 180k tbc (default)
    
    Metadata:
    
      creation_time   : 2016-10-30 16:08:14
    
      handler_name    : VideoHandle

    This seems to detect that the video is 30 fps instead of 960 fps, which is probably why it is filling in with duplicate frames instead of using the existing frames.

    I recording the video on Lenovo Z2 Plus (AKA Zuk Z2). If I playback the video using the built-in player at a slow speed it looks extremely smooth, so the frames are definitely there. Could someone help me figure out the right way ? The file is available here (about 10MB), in case someone would like to try it.

    Update : Video playback at slo-mo on the phone recorded with another phone. Notice how smooth and slow the sparks are thrown around, which is impossible if the original video is 30fps.

  • Evolution #2269 : Prise en compte des variantes d’une langue

    31 août 2011, par Valéry-Xavier LENTZ

    Il me faut donc ajouter le français canadien dans l’interface de gestion des traductions comme cela a été fait pour le brésilien, pour que ce soit présent dans une future version ? Mais du coup il faut dupliquer l’ensemble des fichiers de langue alors que dans 90% des cas le texte sera le (...)

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