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• How to set header metadata to encoded video ?

  11 juin 2013, par Jona

  I'm encoding some images into an h264 video inside an mp4 container. I'm essentially using the ffmpeg example muxing.c. The thing is I'm trying to set some metadata in the mp4 container such as artist, title, etc...

  I thought using the following would work but it didn't :

  AVDictionary *opts = NULL;
  
  av_dict_set(&opts, "title", "Super Lucky Dude", 0);
  
  av_dict_set(&opts, "author", "Jacky Chan", 0);
  
  av_dict_set(&opts, "album", "Chinese Movie", 0);
  
  av_dict_set(&opts, "year", "05/10/2013", 0);
  
  av_dict_set(&opts, "comment", "This video was created using example app.", 0);
  
  av_dict_set(&opts, "genre", "Action", 0);
  
  
  
  // Write the stream header, if any.
  
  ret = avformat_write_header(oc, &opts);

  After the whole video is created I don't see any metadata written to the video file. Any pointers how to actually do this properly ?

• How to change metadata with ffmpeg/avconv without creating a new file ?

  16 mars, par Stephan Kulla

  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.

  


• ffmpeg - adding Dynamic logo & random position watermark to video ?

  9 août 2021, par JackS

  I am making a tutorial for sending through mail to my uses, and to avoid piracy distribution I thought to put watermarks (logo.png) at random places at interval on the videos.

  


  I tried using the command from ffmpeg - Dynamic letters and random position watermark to video ? :

  


  ffmpeg -i input.mp4 \
-vf \
"drawtext=fontfile=font.ttf:fontsize=80:fontcolor=yellow@0.5:text='studentname': \
 x=if(eq(mod(t\,30)\,0)\,rand(0\,(W-tw))\,x): \
 y=if(eq(mod(t\,30)\,0)\,rand(0\,(H-th))\,y)" \
-c:v libx264 -crf 23 -c:a copy output.mp4


  


  But it gave me error :

  


  [NULL @ 0x55c812525600] Unable to find a suitable output format for '\'
\: Invalid argument