一，用ffmpeg命令来操作
下载后，不用做过多的配置和修改, 直接使用
从音频文件中提取出专辑封面图片：
$ ./ffmpeg.exe -i 黑色毛衣\ -\ 周杰伦.mp3 bb.jpg
ffmpeg version N-92237-g305e523105 Copyright (c) 2000-2018 the FFmpeg developers
built with gcc 8.2.1 (GCC) 20181017
configuration: --enable-gpl --enable-version3 --enable-sdl2 --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libtheora --enable-libtwolame --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libzimg --enable-lzma --enable-zlib --enable-gmp --enable-libvidstab --enable-libvorbis --enable-libvo-amrwbenc --enable-libmysofa --enable-libspeex --enable-libxvid --enable-libaom --enable-libmfx --enable-amf --enable-ffnvcodec --enable-cuvid --enable-d3d11va --enable-nvenc --enable-nvdec --enable-dxva2 --enable-avisynth
libavutil 56. 19.101 / 56. 19.101
libavcodec 58. 33.102 / 58. 33.102
libavformat 58. 19.101 / 58. 19.101
libavdevice 58. 4.105 / 58. 4.105
libavfilter 7. 36.100 / 7. 36.100
libswscale 5. 2.100 / 5. 2.100
libswresample 3. 2.100 / 3. 2.100
libpostproc 55. 2.100 / 55. 2.100
Input #0, mp3, from '黑色毛衣 - 周杰伦.mp3':
Metadata:
title : 黑色毛衣
artist : 周杰伦
album : 十一月的萧邦
Duration: 00:04:11.64, start: 0.025056, bitrate: 128 kb/s
Stream #0:0: Audio: mp3, 44100 Hz, stereo, fltp, 128 kb/s
Metadata:
encoder : LAME3.98r
Side data:
replaygain: track gain - -7.700000, track peak - unknown, album gain - unknown, album peak - unknown,
Stream #0:1: Video: mjpeg, yuvj420p(pc, bt470bg/unknown/unknown), 500x500 [SAR 1:1 DAR 1:1], 90k tbr, 90k tbn, 90k tbc
Metadata:
comment : Cover (front)
Stream mapping:
Stream #0:1 -> #0:0 (mjpeg (native) -> mjpeg (native))
Press [q] to stop, [?] for help
[image2 @ 000002284216ae40] 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, image2, to 'bb.jpg':
Metadata:
title : 黑色毛衣
artist : 周杰伦
album : 十一月的萧邦
encoder : Lavf58.19.101
Stream #0:0: Video: mjpeg, yuvj420p(pc), 500x500 [SAR 1:1 DAR 1:1], q=2-31, 200 kb/s, 90k fps, 90k tbn, 90k tbc
Metadata:
comment : Cover (front)
encoder : Lavc58.33.102 mjpeg
Side data:
cpb: bitrate max/min/avg: 0/0/200000 buffer size: 0 vbv_delay: -1
frame= 1 fps=0.0 q=6.2 Lsize=N/A time=00:00:00.00 bitrate=N/A speed=0.00217x
video:22kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown
执行完这条命令后，专辑封面图片会保存在bb.jpg文件中；
往音频文件中添加专辑封面：
ffmpeg -y -i audio1.mp3 -i cover.jpg -map 0:0 -map 1:0 -c copy -id3v2_version 3 audio2.mp3
执行完这条命令后，audio2.mp3中便会包含cover.jpg作为它的专辑封面了。