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• How to change metadata with ffmpeg/avconv ?

  14 juillet 2012, par tampis

  I am writing a python script for producing audio and video podcasts. There are a bunch of recorded media files (audio and video) and text files containing the meta information.

  Now I want to program a function which shall add the information from the meta data text files to all media files (the original and the converted ones). Because I have to handle many different file formats (wav, flac, mp3, mp4, ogg, ogv...) it would be great to have a tool which add meta data to arbitrary formats.

  My Question :

  How can I change the metadata of a file with ffmpeg/avconv without changing the audio or video of it and without creating a new file ? Is there another commandline/python tool which would do the job for me ?

  What I tried so far :

  I thought ffmpeg/avconv could be such a tool, because it can handle nearly all media formats. I hoped, that if I set -i input_file and the output_file to the same file, ffmpeg/avconv will be smart enough to leave the file unchanged. Then I could set -metadata key=value and just the metadata will be changed.

  But I noticed, that if I type avconv -i test.mp3 -metadata title='Test title' test.mp3 the audio test.mp3 will be reconverted in another bitrate.

  So I thought to use -c copy to copy all video and audio information. Unfortunately also this does not work :

  :~$ du -h test.wav # test.wav is 303 MB big
  
  303M    test.wav
  
  
  
  :~$ avconv -i test.wav -c copy -metadata title='Test title' test.wav
  
  avconv version 0.8.3-4:0.8.3-0ubuntu0.12.04.1, Copyright (c) 2000-2012 the
  
  Libav    developers
  
  built on Jun 12 2012 16:37:58 with gcc 4.6.3
  
  [wav @ 0x846b260] max_analyze_duration reached
  
  Input #0, wav, from 'test.wav':
  
  Duration: 00:29:58.74, bitrate: 1411 kb/s
  
      Stream #0.0: Audio: pcm_s16le, 44100 Hz, 2 channels, s16, 1411 kb/s
  
  File 'test.wav' already exists. Overwrite ? [y/N] y
  
  Output #0, wav, to 'test.wav':
  
  Metadata:
  
      title           : Test title
  
      encoder         : Lavf53.21.0
  
      Stream #0.0: Audio: pcm_s16le, 44100 Hz, 2 channels, 1411 kb/s
  
  Stream mapping:
  
  Stream #0:0 -> #0:0 (copy)
  
  Press ctrl-c to stop encoding
  
  size=     896kB time=5.20 bitrate=1411.3kbits/s    
  
  video:0kB audio:896kB global headers:0kB muxing overhead 0.005014%
  
  
  
  :~$ du -h test.wav # file size of test.wav changed dramatically
  
  900K    test.wav

  You see, that I cannot use -c copy if input_file and output_file are the same. Of course I could produce a temporarily file :

  :-$ avconv -i test.wav -c copy -metadata title='Test title' test_temp.mp3
  
  :-$ mv test_tmp.mp3 test.mp3

  But this solution would create (temporarily) a new file on the filesystem and is therefore not preferable.

• Getting video sped-up with FFmpeg to have the correct duration

  23 juin 2023, par Vincent Tjeng

  I've been speeding up video using ffmpeg by following these instructions. For example, to speed up the video by 4 times, I run the following command :

  



  ffmpeg -i vid.MP4 -filter:v "setpts=0.25*PTS" vid_fast.MP4


  



  While the video is sped up by the indicated amount, the duration of the video (as indicated under its properties, and also when I play the video in VLC) remains the same as the original. For example, if vid.MP4 is initially 4 minutes, then vid_fast.MP4 is also 4 minutes, rather than being 1 minute long as expected. (The additional 3 minutes just consist of the video being frozen on the last frame.)

  



  This is a bit of a hassle, since I need to delete the additional 3 minutes that I'm not interested in. Is there any way to avoid this ?

  



  Here is a bit more information on the version of ffmpeg I'm using :

  



  ffmpeg version N-69060-gcd960c8 Copyright (c) 2000-2015 the FFmpeg developers
  built on Jan 14 2015 22:13:45 with gcc 4.9.2 (GCC)
  configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-av
isynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enab
le-iconv --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --
enable-libfreetype --enable-libgme --enable-libgsm --enable-libilbc --enable-lib
modplug --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrw
b --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libschroedinge
r --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --en
able-libvidstab --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-libvorbis
 --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-
libx265 --enable-libxavs --enable-libxvid --enable-lzma --enable-decklink --enab
le-zlib
  libavutil      54. 16.100 / 54. 16.100
  libavcodec     56. 20.100 / 56. 20.100
  libavformat    56. 18.101 / 56. 18.101
  libavdevice    56.  4.100 / 56.  4.100
  libavfilter     5.  7.101 /  5.  7.101
  libswscale      3.  1.101 /  3.  1.101
  libswresample   1.  1.100 /  1.  1.100
  libpostproc    53.  3.100 / 53.  3.100
Hyper fast Audio and Video encoder


  


• Getting video sped-up with FFmpeg to have the correct duration

  1er septembre 2015, par Vincent Tjeng

  I’ve been speeding up video using ffmpeg by following these instructions. For example, to speed up the video by 4 times, I run the following command :

  ffmpeg -i vid.MP4 -filter:v "setpts=0.25*PTS" vid_fast.MP4

  While the video is sped up by the indicated amount, the duration of the video (as indicated under its properties, and also when I play the video in VLC) remains the same as the original. For example, if vid.MP4 is initially 4 minutes, then vid_fast.MP4 is also 4 minutes, rather than being 1 minute long as expected. (The additional 3 minutes just consist of the video being frozen on the last frame.)

  This is a bit of a hassle, since I need to delete the additional 3 minutes that I’m not interested in. Is there any way to avoid this ?

  Here is a bit more information on the version of ffmpeg I’m using :

  ffmpeg version N-69060-gcd960c8 Copyright (c) 2000-2015 the FFmpeg developers
  
    built on Jan 14 2015 22:13:45 with gcc 4.9.2 (GCC)
  
    configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-av
  
  isynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enab
  
  le-iconv --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --
  
  enable-libfreetype --enable-libgme --enable-libgsm --enable-libilbc --enable-lib
  
  modplug --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrw
  
  b --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libschroedinge
  
  r --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --en
  
  able-libvidstab --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-libvorbis
  
   --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-
  
  libx265 --enable-libxavs --enable-libxvid --enable-lzma --enable-decklink --enab
  
  le-zlib
  
    libavutil      54. 16.100 / 54. 16.100
  
    libavcodec     56. 20.100 / 56. 20.100
  
    libavformat    56. 18.101 / 56. 18.101
  
    libavdevice    56.  4.100 / 56.  4.100
  
    libavfilter     5.  7.101 /  5.  7.101
  
    libswscale      3.  1.101 /  3.  1.101
  
    libswresample   1.  1.100 /  1.  1.100
  
    libpostproc    53.  3.100 / 53.  3.100
  
  Hyper fast Audio and Video encoder