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. Continue reading...
