emulator.exe -help-audio-in on Windows produces "unknown option: -help-audio-in"

The emulator documentation says:

  -audio-in <backend>   Use the specified audio-input backend.

It also says that

  -help-<option>    Print help for a specific startup option.

Which means that -help-audio-in should list available backends.

But when I type "emulator.exe -help-audio-in" I receive:

  unknown opti开发者_StackOverflowon: -help-audio-in
  please use -help for a list of valid topics

Well, when I type ""emulator.exe -help" I receive the same information as in the documentation:

  -help-<option>    Print options-specific help.

This is a catch 22 situation... How do I get the list of audio "backends" for the emulator in Windows?

Answering myself: There isn't any -help-audio-in because the emulator doesn't have an audioInput to hook.