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• ffmpeg fails to copy correct duration

  2 février 2016, par guneykayim

  I want to trim a video with the following command :

  ffmpeg.exe -i in.mp4 -ss 76 -t 10 -c copy -an out.mp4

  which exactly means, copy 10 seconds after 76 seconds, and don’t copy audio. However out.mp4 is 5 seconds length.

  This is ffmpeg console output :

  ffmpeg.exe -i in.mp4 -ss 76 -t 10 -c copy -an out.mp4
  
  ffmpeg version N-78197-g5893e87 Copyright (c) 2000-2016 the FFmpeg developers
  
    built with gcc 5.2.0 (GCC)
  
    configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-avisynth --enable-bzli
  
  b --enable-fontconfig --enable-frei0r --enable-gnutls --enable-iconv --enable-libass --enable-libblu
  
  ray --enable-libbs2b --enable-libcaca --enable-libdcadec --enable-libfreetype --enable-libgme --enab
  
  le-libgsm --enable-libilbc --enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb --enab
  
  le-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libschroedinger
  
   --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvidstab --ena
  
  ble-libvo-aacenc --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavpack --en
  
  able-libwebp --enable-libx264 --enable-libx265 --enable-libxavs --enable-libxvid --enable-libzimg --
  
  enable-lzma --enable-decklink --enable-zlib
  
    libavutil      55. 16.101 / 55. 16.101
  
    libavcodec     57. 22.102 / 57. 22.102
  
    libavformat    57. 23.101 / 57. 23.101
  
    libavdevice    57.  0.101 / 57.  0.101
  
    libavfilter     6. 27.100 /  6. 27.100
  
    libswscale      4.  0.100 /  4.  0.100
  
    libswresample   2.  0.101 /  2.  0.101
  
    libpostproc    54.  0.100 / 54.  0.100
  
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'in.mp4':
  
    Metadata:
  
      major_brand     : isom
  
      minor_version   : 512
  
      compatible_brands: isomiso2avc1mp41
  
      encoder         : Lavf54.63.104
  
    Duration: 00:02:28.54, start: 0.000000, bitrate: 2018 kb/s
  
      Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1920x1056 [SAR 1:1 DAR 20:11]
  
  , 1887 kb/s, 23.98 fps, 23.98 tbr, 90k tbn, 47.95 tbc (default)
  
      Metadata:
  
        handler_name    : VideoHandler
  
      Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 125 kb/s (default
  
  )
  
      Metadata:
  
        handler_name    : SoundHandler
  
  Output #0, mp4, to 'out.mp4':
  
    Metadata:
  
      major_brand     : isom
  
      minor_version   : 512
  
      compatible_brands: isomiso2avc1mp41
  
      encoder         : Lavf57.23.101
  
      Stream #0:0(und): Video: h264 ([33][0][0][0] / 0x0021), yuv420p, 1920x1056 [SAR 1:1 DAR 20:11],
  
  q=2-31, 1887 kb/s, 23.98 fps, 23.98 tbr, 90k tbn, 90k tbc (default)
  
      Metadata:
  
        handler_name    : VideoHandler
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (copy)
  
  Press [q] to stop, [?] for help
  
  frame=  143 fps=0.0 q=-1.0 Lsize=    1502kB time=00:00:09.96 bitrate=1235.5kbits/s speed= 524x
  
  video:1499kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.194616%

  When I analyze this console output I see this inconsistency. It says output time is 9.96 seconds. On the other hand it says frame is 143, so from the latter information I can calculate duration by frame/fps which is 143/23.98=5.96.

  Another strange behaviour with this copy command is when I change the start time to something else output video length is varying between 5-10 seconds depending on the start time.

  What might be the problem causing these unexpected behaviours ?

• How to set PSNR value, also what is the minimum PSNR value which shows no visible artifact (no visible distortion)

  20 août 2015, par mrana

  I have 2 issues to ask :
  Q# 1. I have resized the video from 1920x1080 to 480:270 (good ratio 16:9) losslessly by the following command : ffmpeg -f rawvideo -pix_fmt yuv422p -s:v 1920x1080 -r 25 -i above_marathon_250.yuv -c:v libx264 -vf scale=480:270 -qp 0 above_marathon_250.mp4
  Once i am trying to find the PSNR value using the following command : ffmpeg -f rawvideo -pix_fmt yuv422p -s:v 1920x1080 -r 25 -i above_marathon_250.yuv -i above_marathon_250.mp4 -lavfi psnr -f null -
  
  I am getting the following problem : https://www.dropbox.com/s/h2djohk3d3q6uj6/Screen%20Shot%202015-08-20%20at%2018.43.24.png?dl=0

  Q# 2. What is the minimum value of PSNR for no visible artifact(no visible distortion), and how can i set it with the above command ?

  Thanks so much.

• Révision 23619 : On nécessite PHP 5.4 minimum.

  20 juin 2017, par marcimat@rezo.net

  Note : Debian 7 Wheezy est supportée avec PHP 5.4 jusque fin mai 2018…