直接看命令：

E:\BaiduNetdiskDownload>ffmpeg -i roundDeskS02E01.mp4 -acodec pcm_s16le -f s16le -ac 1 -ar 16000 roundDeskS02E01.pcm
ffmpeg version git-2020-03-06-cfd9a65 Copyright (c) 2000-2020 the FFmpeg developers
  built with gcc 9.2.1 (GCC) 20200122
  configuration: --enable-gpl --enable-version3 --enable-sdl2 --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass --enable-libdav1d --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-ffnvcodec --enable-cuda-llvm --enable-cuvid --enable-d3d11va --enable-nvenc --enable-nvdec --enable-dxva2 --enable-avisynth --enable-libopenmpt --enable-amf
  libavutil      
 
56. 42.100 / 56. 42.100
  libavcodec     58. 73.102 / 58. 73.102
  libavformat    58. 39.101 / 58. 39.101
  libavdevice    58.  9.103 / 58.  9.103
  libavfilter     7. 77.100 /  7. 77.100
  libswscale      5.  6.100 /  5.  6.100
  libswresample   3.  6.100 /  3.  6.100
  libpostproc    55.  6.100 / 55.  6.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from
 
 'roundDeskS02E01.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.20.100
  Duration: 00:39:54.27, start: 0.000000, bitrate: 815 kb/s
    Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1080x606, 744 kb/s, 25 fps, 25
 
 tbr, 90k tbn, 50 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 64 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
File 'roundDeskS02E01.pcm' already exists. Overwrite? [y/N] y
Stream mapping:
  Stream #0:1 -> #0:0 (aac (native) -> pcm_s16le (native))
Press [q] to stop, [?] for help
Output #0, s16le, to 'roundDeskS02E01.pcm':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.39.101
    Stream #0:0(und): Audio: pcm_s16le, 16000 Hz, mono, s16, 256 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
      encoder         : Lavc58.73.102 pcm_s16le
size=   74821kB time=00:39:54.26 bitrate= 256.0kbits/s speed= 303x
video:0kB audio:74821kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.000000%

　　引數說明：

　　1、-acodec pcm_s16le -> acodec：音訊編碼，pcm：pcm原始音訊，s16：取樣位為16位，le：小端點

　　2、-f s16le -> f：音訊格式，s16le：參見上面

　　3、-ac 1 -> ac：聲道數，指定1

　　4、-ar 16000 -> ar：採用率，指定16K

　　轉好之後可以到這裡試試能否正常播放http://support.bjdn.openstorage.cn/api/pcm_player/index.html