title: Convert m4a to aac and keep metadata on Windows 7
body: <p>I want to convert an m4a file to aac*. I can do this using:</p>
  
  <pre><code>ffmpeg -i song.m4a -acodec copy song.aac
  </code></pre>
  
  <p>But on Windows 7 the metadata is not compatible. It seems the <code>-id3v2_version 3</code> flag should be used so that Windows compatible ID3 tags version 2.3 are used:</p>
  
  <pre><code>ffmpeg -i song.m4a -acodec copy -id3v2_version 3 song.aac
  </code></pre>
  
  <p>However, with the above command I still don't get any metadata in song.aac. I have used windows file explorer, mp3tag and winamp to confirm there are no tags.</p>
  
  <p>*: reason; m4a won't play on the car stereo so following this advice (<a href="http://www.vwaudiforum.co.uk/forum/showthread.php?153728-Tip-Getting-M4A-(iTunes)-format-music-to-play-on-a-VW-head-unit" rel="nofollow">http://www.vwaudiforum.co.uk/forum/showthread.php?153728-Tip-Getting-M4A-(iTunes)-format-music-to-play-on-a-VW-head-unit</a>)</p>
  
  <p>Console Output:</p>
  
  <pre><code>C:\temp&gt;ffmpeg -i song.m4a -acodec copy -id3v2_version 3 song.aac
  ffmpeg version N-67914-gf87a344 Copyright (c) 2000-2014 the FFmpeg developers
    built on Nov 22 2014 22:10:18 with gcc 4.9.2 (GCC)
    configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-avisynth --enable-bzlib --enable-fontconfi
  g --enable-frei0r --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --
  enable-libfreetype --enable-libgme --enable-libgsm --enable-libilbc --enable-libmodplug --enable-libmp3lame --enable-lib
  opencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libschroedinge
  r --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvo-aacenc --
  enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-
  libx265 --enable-libxavs --enable-libxvid --enable-zlib
    libavutil      54. 15.100 / 54. 15.100
    libavcodec     56. 13.100 / 56. 13.100
    libavformat    56. 15.100 / 56. 15.100
    libavdevice    56.  3.100 / 56.  3.100
    libavfilter     5.  2.103 /  5.  2.103
    libswscale      3.  1.101 /  3.  1.101
    libswresample   1.  1.100 /  1.  1.100
    libpostproc    53.  3.100 / 53.  3.100
  [mov,mp4,m4a,3gp,3g2,mj2 @ 0000000002dcc760] stream 0, timescale not set
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'song.m4a':
    Metadata:
      major_brand     : M4A
      minor_version   : 0
      compatible_brands: M4A mp42isom
      creation_time   : 1980-07-20 13:32:00
      iTunSMPB        :  00000000 00000840 0000007C 0000000001027F44 00000000 00000000 00000000 00000000 00000000 00000000
   00000000 00000000
      iTunNORM        :  0000061A 0000052A 00001C40 000021EE 00035E0A 00046912 00007B8C 00007B99 0002845B 00024D35
      title           : Time Away
      artist          : Andy Stott
      album_artist    : Andy Stott
      album           : Faith In Strangers
      genre           : Electronic
      track           : 1/9
      disc            : 1/1
      compilation     : 0
      gapless_playback: 0
      date            : 2014-11-17T08:00:00Z
      copyright       : Ôäù 2014 Modern Love
      media_type      : 1
      iTunMOVI        : &lt;?xml version="1.0" encoding="UTF-8"?&gt;
                      : &lt;!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.d
  td"&gt;
                      : &lt;plist version="1.0"&gt;
                      : &lt;dict&gt;
                      :   &lt;key&gt;asset-info&lt;/key&gt;
                      :   &lt;dict&gt;
                      :           &lt;key&gt;file-size&lt;/key&gt;
                      :           &lt;integer&gt;14359364&lt;/integer&gt;
                      :           &lt;key&gt;flavor&lt;/key&gt;
                      :           &lt;string&gt;2:256&lt;/string&gt;
                      :   &lt;/dict&gt;
                      : &lt;/dict&gt;
                      : &lt;/plist&gt;
                      :
    Duration: 00:06:24.20, start: 0.000000, bitrate: 298 kb/s
      Stream #0:0(eng): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 285 kb/s (default)
      Metadata:
        creation_time   : 1980-07-20 13:32:00
      Stream #0:1: Video: mjpeg, gray(bt470bg/unknown/unknown), 1400x1400 [SAR 300:300 DAR 1:1], 90k tbr, 90k tbn, 90k tbc
  
  Output #0, adts, to 'song.aac':
    Metadata:
      major_brand     : M4A
      minor_version   : 0
      compatible_brands: M4A mp42isom
      iTunMOVI        : &lt;?xml version="1.0" encoding="UTF-8"?&gt;
                      : &lt;!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.d
  td"&gt;
                      : &lt;plist version="1.0"&gt;
                      : &lt;dict&gt;
                      :   &lt;key&gt;asset-info&lt;/key&gt;
                      :   &lt;dict&gt;
                      :           &lt;key&gt;file-size&lt;/key&gt;
                      :           &lt;integer&gt;14359364&lt;/integer&gt;
                      :           &lt;key&gt;flavor&lt;/key&gt;
                      :           &lt;string&gt;2:256&lt;/string&gt;
                      :   &lt;/dict&gt;
                      : &lt;/dict&gt;
                      : &lt;/plist&gt;
                      :
      iTunSMPB        :  00000000 00000840 0000007C 0000000001027F44 00000000 00000000 00000000 00000000 00000000 00000000
   00000000 00000000
      iTunNORM        :  0000061A 0000052A 00001C40 000021EE 00035E0A 00046912 00007B8C 00007B99 0002845B 00024D35
      title           : Time Away
      artist          : Andy Stott
      album_artist    : Andy Stott
      album           : Faith In Strangers
      genre           : Electronic
      track           : 1/9
      disc            : 1/1
      compilation     : 0
      gapless_playback: 0
      date            : 2014-11-17T08:00:00Z
      copyright       : Ôäù 2014 Modern Love
      media_type      : 1
      encoder         : Lavf56.15.100
      Stream #0:0(eng): Audio: aac (mp4a / 0x6134706D), 44100 Hz, stereo, 285 kb/s (default)
      Metadata:
        creation_time   : 1980-07-20 13:32:00
  Stream mapping:
    Stream #0:0 -&gt; #0:0 (copy)
  Press [q] to stop, [?] for help
  size=   13523kB time=00:06:24.19 bitrate= 288.3kbits/s
  video:0kB audio:13410kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.843272%
  
  C:\temp&gt;
  </code></pre>