title: How to encode specific metadata version in FFMPEG?
body: <p>I am batch converting lots of songs into shorter "Advert" songs for SHOUTcast and to be recognised as adverts by the server. The song must have <code>":Advert"</code> for both the title and the artist metadata tags. When I use the following command:</p>
  
  <pre><code>ffmpeg -i "$i" -c copy -vn -map_metadata -1 -metadata title=":Advert" -metadata artist=":Advert" -t 120 "adverts/ADVERT_$i"
  </code></pre>
  
  <p>I would expect it to output the song with only <code>":Advert"</code> as title and artist metadata but when I import it into the radio playout software (using ID3 1.x tagging) the metadata has not copied across and is therefore lost. Output from ffmpeg:</p>
  
  <pre><code>ffmpeg version 3.0.2 Copyright (c) 2000-2016 the FFmpeg developers
    built with Apple LLVM version 9.0.0 (clang-900.0.37)
    configuration: --prefix=/usr/local/Cellar/ffmpeg/3.0.2 --enable-shared --enable-pthreads --enable-gpl --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-opencl --enable-libx264 --enable-libmp3lame --enable-libxvid --disable-lzma --enable-vda
    libavutil      55. 17.103 / 55. 17.103
    libavcodec     57. 24.102 / 57. 24.102
    libavformat    57. 25.100 / 57. 25.100
    libavdevice    57.  0.101 / 57.  0.101
    libavfilter     6. 31.100 /  6. 31.100
    libavresample   3.  0.  0 /  3.  0.  0
    libswscale      4.  0.100 /  4.  0.100
    libswresample   2.  0.101 /  2.  0.101
    libpostproc    54.  0.100 / 54.  0.100
  [mp3 @ 0x7feba6800000] Skipping 0 bytes of junk at 230934.
  [mjpeg @ 0x7feba7000600] Changing bps to 8
  Input #0, mp3, from 'Joakim Karud - Vibe With Me.mp3':
    Metadata:
      major_brand     : dash
      minor_version   : 0
      compatible_brands: iso6mp41
      encoder         : Lavf56.40.101
      artist          : Joakim Karud
      title           : Vibe With Me
    Duration: 00:02:53.06, start: 0.025056, bitrate: 138 kb/s
      Stream #0:0: Audio: mp3, 44100 Hz, stereo, s16p, 128 kb/s
      Metadata:
        encoder         : Lavc56.60
      Stream #0:1: Video: mjpeg, yuvj420p(pc, bt470bg/unknown/unknown), 1280x720 [SAR 1:1 DAR 16:9], 90k tbr, 90k tbn, 90k tbc
      Metadata:
        comment         : Cover (front)
  Output #0, mp3, to 'adverts/ADVERT_Joakim Karud - Vibe With Me.mp3':
    Metadata:
      TIT2            : :Advert
      TPE1            : :Advert
      TSSE            : Lavf57.25.100
      Stream #0:0: Audio: mp3, 44100 Hz, stereo, 128 kb/s
  Stream mapping:
    Stream #0:0 -&gt; #0:0 (copy)
  Press [q] to stop, [?] for help
  size=    1876kB time=00:02:00.00 bitrate= 128.1kbits/s speed=1.44e+03x
  video:0kB audio:1876kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.024837%
  </code></pre>
  
  <p>I believe this is happening because the tag names are different (e.g. title should be <code>title</code>, but is <code>TIT2</code> when output. Please could someone specify how I could ensure that the metadata is encoded in the ID3 1.x format so that it is readable by the radio playout software. Many thanks.</p>