將m4a轉換爲aac並在Windows 7上保留元數據

Question

我想將m4a文件轉換爲aac *。我可以這樣做：

ffmpeg -i song.m4a -acodec copy song.aac 

但是在Windows 7上元數據不兼容。看來-id3v2_version 3標誌應採用讓Windows兼容的ID3標籤版本2.3中使用：

ffmpeg -i song.m4a -acodec copy -id3v2_version 3 song.aac 

然而，上面的命令我還沒有得到任何song.aac元。我用Windows文件瀏覽器，mp3tag和winamp來確認沒有標籤。

*：reason; M4A不會對汽車音響打那麼下面這條建議（http://www.vwaudiforum.co.uk/forum/showthread.php?153728-Tip-Getting-M4A-(iTunes)-format-music-to-play-on-a-VW-head-unit）

控制檯輸出：

C:\temp>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  : <?xml version="1.0" encoding="UTF-8"?> 
        : <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.d 
td"> 
        : <plist version="1.0"> 
        : <dict> 
        : <key>asset-info</key> 
        : <dict> 
        :   <key>file-size</key> 
        :   <integer>14359364</integer> 
        :   <key>flavor</key> 
        :   <string>2:256</string> 
        : </dict> 
        : </dict> 
        : </plist> 
        : 
    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  : <?xml version="1.0" encoding="UTF-8"?> 
        : <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.d 
td"> 
        : <plist version="1.0"> 
        : <dict> 
        : <key>asset-info</key> 
        : <dict> 
        :   <key>file-size</key> 
        :   <integer>14359364</integer> 
        :   <key>flavor</key> 
        :   <string>2:256</string> 
        : </dict> 
        : </dict> 
        : </plist> 
        : 
    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 -> #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> 

Answer 1

究其原因，文件將不能在汽車音響播放可能不是M4A，這大概是的fastStart

FFmpeg corrupts iTunes files