我在这里按照教程进行操作，执行第一个示例命令会产生错误。
我拥有的 ffmpeg 版本启用了 libvpx 和 libvorbis。
当我运行这个命令时：ffmpeg -i aaa.mp4 -c:v libvpx -b:v 1M -c:a libvorbis output.webm，我得到：
ffmpeg version 4.3 Copyright (c) 2000-2020 the FFmpeg developers
built with gcc 9.3.1 (GCC) 20200621
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-libsrt --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-libvmaf --enable-libvorbis --enable-libvo-amrwbenc --enable-libmysofa --enable-libspeex --enable-libxvid --enable-libaom --enable-libgsm --disable-w32threads --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. 51.100 / 56. 51.100
libavcodec 58. 91.100 / 58. 91.100
libavformat 58. 45.100 / 58. 45.100
libavdevice 58. 10.100 / 58. 10.100
libavfilter 7. 85.100 / 7. 85.100
libswscale 5. 7.100 / 5. 7.100
libswresample 3. 7.100 / 3. 7.100
libpostproc 55. 7.100 / 55. 7.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'aaa.mp4':
Metadata:
major_brand : mp42
minor_version : 0
compatible_brands: mp42mp41
creation_time : 2019-11-19T16:35:35.000000Z
Duration: 00:00:37.33, start: 0.000000, bitrate: 18672 kb/s
Stream #0:0(eng): Video: h264 (Main) (avc1 / 0x31637661), yuv420p(tv, bt709), 1920x1080, 18375 kb/s, 25 fps, 25 tbr, 25k tbn, 50 tbc (default)
Metadata:
creation_time : 2019-11-19T16:35:35.000000Z
handler_name : ?Mainconcept Video Media Handler
encoder : AVC Coding
Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 317 kb/s (default)
Metadata:
creation_time : 2019-11-19T16:35:35.000000Z
handler_name : #Mainconcept MP4 Sound Media Handler
[NULL @ 0000018b84220500] Unable to find a suitable output format for 'libvpx'
libvpx: Invalid argument
编辑：
我使用的 ffmpeg 版本是使用 scoop 包管理器安装的，这似乎是问题所在。
