Keep audio metadata (incl. cover art) when transcoding audio files

[Will Lunniss]

The -vn option removes any video streams which are usually used to store album artwork. This may be needed for some devices (seems like the only reason it would be there now), but it isn't needed for CDS clients and results in the transcoded audio files not having any artwork. Here is an example mp3 showing a video stream that contains the album artwork.

#!

Input #0, mp3, from '01 Intro.mp3':
  Metadata:
    TLEN            : 22800
    publisher       : Warner Music
    title           : Intro
    artist          : Muse
    album_artist    : Muse
    album           : Absolution
    track           : 1
    genre           : Rock
    date            : 2003
  Duration: 00:00:23.42, start: 0.000000, bitrate: 127 kb/s
    Stream #0:0: Audio: mp3, 44100 Hz, stereo, s16p, 128 kb/s
    Stream #0:1: Video: mjpeg, yuvj420p, 200x200 [SAR 300:300 DAR 1:1], 90k tbr, 90k tbn, 90k tbc

[Petr Nejedly]

Is the -vn really causing the problem? I think the guy in forum said it makes no difference.

Maybe this should be done instead: http://herself.movielady.net/2011/06/21/convert-flac-to-mp3-using-ffmpeg-retain-id3-tags/

[Will Lunniss]

Just did a quick test starting with an m4a files.

This is what Serviio ran (changed output file)

#!

 ffmpeg -i "/mnt/data0/media/music/Cream/Wheels Of Fire [Disc 1]/09 Deserted Cities Of The Heart.m4a" -y -b:a 192k -ac 2 -vn -f mp3 /mnt/data0/tmp/no_art.stf
ffmpeg version N-50554-gcada996 Copyright (c) 2000-2013 the FFmpeg developers
  built on Mar  7 2013 15:46:47 with gcc 4.4.5 (Debian 4.4.5-8)
  configuration: --enable-ssse3 --enable-gpl --enable-libmp3lame --enable-version3 --enable-nonfree --enable-librtmp --enable-runtime-cpudetect --enable-pthreads --enable-static --disable-shared --disable-ffplay --disable-ffserver --enable-libass --enable-libfreetype --enable-fontconfig
  libavutil      52. 18.100 / 52. 18.100
  libavcodec     54. 92.100 / 54. 92.100
  libavformat    54. 63.104 / 54. 63.104
  libavdevice    54.  3.103 / 54.  3.103
  libavfilter     3. 42.103 /  3. 42.103
  libswscale      2.  2.100 /  2.  2.100
  libswresample   0. 17.102 /  0. 17.102
  libpostproc    52.  2.100 / 52.  2.100
[mov,mp4,m4a,3gp,3g2,mj2 @ 0xa64b3e0] stream 0, timescale not set
[mov,mp4,m4a,3gp,3g2,mj2 @ 0xa64b3e0] max_analyze_duration 5000000 reached at 5015510 microseconds
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/mnt/data0/media/music/Cream/Wheels Of Fire [Disc 1]/09 Deserted Cities Of The Heart.m4a':
  Metadata:
    major_brand     : M4A
    minor_version   : 0
    compatible_brands: M4A mp42isom
    creation_time   : 2010-12-05 17:03:29
    title           : Deserted Cities Of The Heart
    artist          : Cream
    composer        : Peter Brown/Jack Bruce
    album           : Wheels Of Fire [Disc 1]
    genre           : Rock
    track           : 9/9
    disc            : 1/1
    date            : 1968
    gapless_playback: 0
    encoder         : iTunes 10.1.0.54, QuickTime 7.6.8
    album_artist    : Cream
  Duration: 00:03:38.34, start: 0.000000, bitrate: 287 kb/s
    Stream #0:0(und): Audio: aac (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 282 kb/s
    Metadata:
      creation_time   : 2010-12-05 17:03:29
    Stream #0:1: Video: mjpeg, yuvj420p, 600x595 [SAR 72:72 DAR 120:119], 90k tbr, 90k tbn, 90k tbc
Output #0, mp3, to '/mnt/data0/tmp/no_art.stf':
  Metadata:
    major_brand     : M4A
    minor_version   : 0
    compatible_brands: M4A mp42isom
    TPE2            : Cream
    TIT2            : Deserted Cities Of The Heart
    TPE1            : Cream
    TCOM            : Peter Brown/Jack Bruce
    TALB            : Wheels Of Fire [Disc 1]
    TCON            : Rock
    TRCK            : 9/9
    TPOS            : 1/1
    TDRL            : 1968
    gapless_playback: 0
    TSSE            : Lavf54.63.104
    Stream #0:0(und): Audio: mp3, 44100 Hz, stereo, fltp, 192 kb/s
    Metadata:
      creation_time   : 2010-12-05 17:03:29
Stream mapping:
  Stream #0:0 -> #0:0 (aac -> libmp3lame)
Press [q] to stop, [?] for help
size=    5118kB time=00:03:38.35 bitrate= 192.0kbits/s
video:0kB audio:5117kB subtitle:0 global headers:0kB muxing overhead 0.018951%

And it had no artwork, Removing the -vn option gives the following which did have artwork, so -vn does effect some types of conversions

#!

ffmpeg -i "/mnt/data0/media/music/Cream/Wheels Of Fire [Disc 1]/09 Deserted Cities Of The Heart.m4a" -y -b:a 192k -ac 2 -f mp3 /mnt/data0/tmp/with_art.stf
ffmpeg version N-50554-gcada996 Copyright (c) 2000-2013 the FFmpeg developers
  built on Mar  7 2013 15:46:47 with gcc 4.4.5 (Debian 4.4.5-8)
  configuration: --enable-ssse3 --enable-gpl --enable-libmp3lame --enable-version3 --enable-nonfree --enable-librtmp --enable-runtime-cpudetect --enable-pthreads --enable-static --disable-shared --disable-ffplay --disable-ffserver --enable-libass --enable-libfreetype --enable-fontconfig
  libavutil      52. 18.100 / 52. 18.100
  libavcodec     54. 92.100 / 54. 92.100
  libavformat    54. 63.104 / 54. 63.104
  libavdevice    54.  3.103 / 54.  3.103
  libavfilter     3. 42.103 /  3. 42.103
  libswscale      2.  2.100 /  2.  2.100
  libswresample   0. 17.102 /  0. 17.102
  libpostproc    52.  2.100 / 52.  2.100
[mov,mp4,m4a,3gp,3g2,mj2 @ 0xaf343c0] stream 0, timescale not set
[mov,mp4,m4a,3gp,3g2,mj2 @ 0xaf343c0] max_analyze_duration 5000000 reached at 5015510 microseconds
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/mnt/data0/media/music/Cream/Wheels Of Fire [Disc 1]/09 Deserted Cities Of The Heart.m4a':
  Metadata:
    major_brand     : M4A
    minor_version   : 0
    compatible_brands: M4A mp42isom
    creation_time   : 2010-12-05 17:03:29
    title           : Deserted Cities Of The Heart
    artist          : Cream
    composer        : Peter Brown/Jack Bruce
    album           : Wheels Of Fire [Disc 1]
    genre           : Rock
    track           : 9/9
    disc            : 1/1
    date            : 1968
    gapless_playback: 0
    encoder         : iTunes 10.1.0.54, QuickTime 7.6.8
    album_artist    : Cream
  Duration: 00:03:38.34, start: 0.000000, bitrate: 287 kb/s
    Stream #0:0(und): Audio: aac (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 282 kb/s
    Metadata:
      creation_time   : 2010-12-05 17:03:29
    Stream #0:1: Video: mjpeg, yuvj420p, 600x595 [SAR 72:72 DAR 120:119], 90k tbr, 90k tbn, 90k tbc
[mp3 @ 0xaf62540] Frame rate very high for a muxer not efficiently supporting it.
Please consider specifying a lower framerate, a different muxer or -vsync 2
Output #0, mp3, to '/mnt/data0/tmp/with_art.stf':
  Metadata:
    major_brand     : M4A
    minor_version   : 0
    compatible_brands: M4A mp42isom
    TPE2            : Cream
    TIT2            : Deserted Cities Of The Heart
    TPE1            : Cream
    TCOM            : Peter Brown/Jack Bruce
    TALB            : Wheels Of Fire [Disc 1]
    TCON            : Rock
    TRCK            : 9/9
    TPOS            : 1/1
    TDRL            : 1968
    gapless_playback: 0
    TSSE            : Lavf54.63.104
    Stream #0:0: Video: png, rgb24, 600x595 [SAR 1:1 DAR 120:119], q=2-31, 200 kb/s, 90k tbn, 90k tbc
    Stream #0:1(und): Audio: mp3, 44100 Hz, stereo, fltp, 192 kb/s
    Metadata:
      creation_time   : 2010-12-05 17:03:29
Stream mapping:
  Stream #0:1 -> #0:0 (mjpeg -> png)
  Stream #0:0 -> #0:1 (aac -> libmp3lame)
Press [q] to stop, [?] for help
frame=    1 fps=0.0 q=0.0 Lsize=    5574kB time=00:03:38.35 bitrate= 209.1kbits/s
video:456kB audio:5117kB subtitle:0 global headers:0kB muxing overhead 0.017803%

[Petr Nejedly]

Ok, cool. Did you try with the metadata flag?

[Will Lunniss]

And it also needs -id3v2_version 3 added to the options to force ID3v2.3 tags as artwork in 2.4 tags won't seem to be supported under Android (Windows doesn't support 2.4 either).

[Will Lunniss]

I think -map_metadata 0 is only needed for flac. I don't have any to test at the moment.