ffmpeg flac to aac (libdfdk_aac) missing metadata

Question

I want to convert an album from flac to aac. After converting the aac file is missing all metadata from the original flac file. I've already tried to convert it with the -map_metadata 0 argument

My command looked like this:

ffmpeg -i input.flac -c:a libfdk_aac -b:a 320k -map_metadata 0 output.aac

The output:

ffmpeg version N-80283-g84efdab Copyright (c) 2000-2016 the FFmpeg developers
  built with gcc 4.8 (Ubuntu 4.8.4-2ubuntu1~14.04.3)
  configuration: --extra-libs=-ldl --prefix=/opt/ffmpeg --mandir=/usr/share/man --enable-avresample --disable-debug --enable-nonfree --enable-gpl --enable-version3 --enable-libopencore-amrnb --enable-libopencore-amrwb --disable-decoder=amrnb --disable-decoder=amrwb --enable-libpulse --enable-libfreetype --enable-gnutls --enable-libx264 --enable-libx265 --enable-libfdk-aac --enable-libvorbis --enable-libmp3lame --enable-libopus --enable-libvpx --enable-libspeex --enable-libass --enable-avisynth --enable-libsoxr --enable-libxvid --enable-libvidstab
  libavutil      55. 24.100 / 55. 24.100
  libavcodec     57. 46.100 / 57. 46.100
  libavformat    57. 37.101 / 57. 37.101
  libavdevice    57.  0.101 / 57.  0.101
  libavfilter     6. 46.101 /  6. 46.101
  libavresample   3.  0.  0 /  3.  0.  0
  libswscale      4.  1.100 /  4.  1.100
  libswresample   2.  0.101 /  2.  0.101
  libpostproc    54.  0.100 / 54.  0.100
Input #0, flac, from 'Gareth Coker feat. Aeralie Brighton - 01. Ori, Lost In .flac':
  Metadata:
    ALBUM           : Ori and the Blind Forest (Original Soundtrack)
    TITLE           : Ori, Lost In the Storm (feat. Aeralie Brighton)
    ARTIST          : Gareth Coker feat. Aeralie Brighton
    album_artist    : Gareth Coker
    comment         : Purchased from 7digital.com
    track           : 1
    disc            : 1
    TRACKTOTAL      : 32
    GENRE           : Soundtracks
    DATE            : 2015
    COPYRIGHT       : (p) Microsoft
  Duration: 00:01:08.20, start: 0.000000, bitrate: 726 kb/s
    Stream #0:0: Audio: flac, 44100 Hz, stereo, s16
    Stream #0:1: Video: mjpeg, yuvj420p(pc, bt470bg/unknown/unknown), 800x800 [SAR 96:96 DAR 1:1], 90k tbr, 90k tbn, 90k tbc
    Metadata:
      comment         : Cover (front)
      title           : cover.jpg
File '../../../Desktop/aac/output.aac' already exists. Overwrite ? [y/N] y
[adts @ 0x1fb9880] Using AVStream.codec to pass codec parameters to muxers is deprecated, use AVStream.codecpar instead.
Output #0, adts, to '../../../Desktop/aac/output.aac':
  Metadata:
    ALBUM           : Ori and the Blind Forest (Original Soundtrack)
    TITLE           : Ori, Lost In the Storm (feat. Aeralie Brighton)
    ARTIST          : Gareth Coker feat. Aeralie Brighton
    album_artist    : Gareth Coker
    comment         : Purchased from 7digital.com
    track           : 1
    disc            : 1
    TRACKTOTAL      : 32
    GENRE           : Soundtracks
    DATE            : 2015
    COPYRIGHT       : (p) Microsoft
    encoder         : Lavf57.37.101
    Stream #0:0: Audio: aac (libfdk_aac), 44100 Hz, stereo, s16, 320 kb/s
    Metadata:
      encoder         : Lavc57.46.100 libfdk_aac
Stream mapping:
  Stream #0:0 -> #0:0 (flac (native) -> aac (libfdk_aac))
Press [q] to stop, [?] for help
size=    2667kB time=00:01:08.22 bitrate= 320.2kbits/s speed=34.9x
video:0kB audio:2667kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.000000%

And the ffmpeg -i output from the aac file:

ffmpeg version N-80283-g84efdab Copyright (c) 2000-2016 the FFmpeg developers
  built with gcc 4.8 (Ubuntu 4.8.4-2ubuntu1~14.04.3)
  configuration: --extra-libs=-ldl --prefix=/opt/ffmpeg --mandir=/usr/share/man --enable-avresample --disable-debug --enable-nonfree --enable-gpl --enable-version3 --enable-libopencore-amrnb --enable-libopencore-amrwb --disable-decoder=amrnb --disable-decoder=amrwb --enable-libpulse --enable-libfreetype --enable-gnutls --enable-libx264 --enable-libx265 --enable-libfdk-aac --enable-libvorbis --enable-libmp3lame --enable-libopus --enable-libvpx --enable-libspeex --enable-libass --enable-avisynth --enable-libsoxr --enable-libxvid --enable-libvidstab
  libavutil      55. 24.100 / 55. 24.100
  libavcodec     57. 46.100 / 57. 46.100
  libavformat    57. 37.101 / 57. 37.101
  libavdevice    57.  0.101 / 57.  0.101
  libavfilter     6. 46.101 /  6. 46.101
  libavresample   3.  0.  0 /  3.  0.  0
  libswscale      4.  1.100 /  4.  1.100
  libswresample   2.  0.101 /  2.  0.101
  libpostproc    54.  0.100 / 54.  0.100
[aac @ 0x3453660] Estimating duration from bitrate, this may be inaccurate
Input #0, aac, from '../../../Desktop/aac/output.aac':
  Duration: 00:01:08.84, bitrate: 317 kb/s
    Stream #0:0: Audio: aac (LC), 44100 Hz, stereo, fltp, 317 kb/s
At least one output file must be specified

Answer 1

.aac is a raw AAC bitstream and holds no metadata. Output to .m4a or maybe even .mp4.