PowerShell把MP4转换成MP3

可以借助于第三方解码器ffmpe.exe, 下载地址：https://www.ffmpeg.org

具体的调用非常方便，直接通过命令行：

PS> .\ffmpeg.exe -i test.mp4 test.mp3
ffmpeg version N-90518-gaf043b839c Copyright (c) 2000-2018 the FFmpeg developers
  built with gcc 7.3.0 (GCC)
  configuration: --enable-gpl --enable-version3 --enable-sdl2 --enable-bzlib --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. 12.100 / 56. 12.100
  libavcodec     58. 16.100 / 58. 16.100
  libavformat    58. 10.100 / 58. 10.100
  libavdevice    58.  2.100 / 58.  2.100
  libavfilter     7. 13.100 /  7. 13.100
  libswscale      5.  0.102 /  5.  0.102
  libswresample   3.  0.101 /  3.  0.101
  libpostproc    55.  0.100 / 55.  0.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'test.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 1
    compatible_brands: isomavc1
    creation_time   : 2014-02-24T19:15:36.000000Z
  Duration: 00:04:05.11, start: 0.000000, bitrate: 371 kb/s
    Stream #0:0(und): Video: h264 (Constrained Baseline) (avc1 / 0x31637661), yuv420p(tv, smpte170m/smpte170m/bt709), 592x328, 324 kb/s, 15 fps, 15 tbr, 15k tbn, 30 tbc (default)
    Metadata:
      creation_time   : 2014-02-24T19:15:36.000000Z
      handler_name    : 9ec8990d9b4d28c0b813078cb3d30ea0_tmp_video.264 - Imported with GPAC 0.4.6.1-DEV-revexported
    Stream #0:1(und): Audio: aac (HE-AAC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 47 kb/s (default)
    Metadata:
      creation_time   : 2014-02-24T19:15:36.000000Z
      handler_name    : GPAC ISO Audio Handler
Stream mapping:
  Stream #0:1 -> #0:0 (aac (native) -> mp3 (libmp3lame))
Press [q] to stop, [?] for help
Output #0, mp3, to 'test.mp3':
  Metadata:
    major_brand     : isom
    minor_version   : 1
    compatible_brands: isomavc1
    TSSE            : Lavf58.10.100
    Stream #0:0(und): Audio: mp3 (libmp3lame), 44100 Hz, stereo, fltp (default)
    Metadata:
      creation_time   : 2014-02-24T19:15:36.000000Z
      handler_name    : GPAC ISO Audio Handler
      encoder         : Lavc58.16.100 libmp3lame
size=    3831kB time=00:04:05.13 bitrate= 128.0kbits/s speed=  18x
video:0kB audio:3831kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.008821%