A simple record and playback volume control class

  Sometimes we need to control the volume, and Microsoft really provided
a api waveOutSetVolume() to do this. but unfortunately, this can only set
the waveout tunnle of the playback volume.when we want to set the volume of
other line, such as mic , midi of the playback or linein of the record, there
is NO api can help work!
  At first, I think that DirectMedia may provide a interface to do this, and 
it really dose, but after I coded it and tested, the result is not so good,
interface IAMAudioInputMixer can only handle the record, not the playback, and
most of all:
"The name of each pin, such as "Line in" or "Microphone", reflects the type of input"
but the name is not the same in different machine!!

eg:
  I want to set the volume of the microphone, so I find the pin by name "Microphone" 
and control it, it work at my computer. when I test it at another machine, it failed
because the name of the pin is "Mic Volume"!!!!

  I tried many ways and at last I work it out with MIXER.

  There may be some people that feel headache about the same quetion, so I released 
my solution, hope it help you.

usage:
  include the Mixer.h and Mixer.cpp into your project;

  add code like this:

  CMixer mixer(MIXERLINE_COMPONENTTYPE_SRC_MICROPHONE, CMixer::Record);

  ......
  mixer.GetVolume();
  mixer.SetVolume(...);


remark:
  the constructor take two parameters, the first is ComponentType
from MIXERLINE(see MSDN for all), the second is a enum type, which
can be Record or Play.
  the above control the record(waveIn) volume, you can alse control 
the playback(waveout) volume by code like this:

  CMixer mixer(MIXERLINE_COMPONENTTYPE_SRC_MICROPHONE, CMixer::Play);


  notice that there is no default constructor take zero params, so if 
you use it in a c++ class, you should code it like this:

// MyClass.h
//////////////////////////
class CMixer;
class CMyClass
{
  CMyClass();
private:
  CMixer m_mixer;
....
}

//MyClass.cpp
///////////////////////////
CMyClass::CMyClass():m_mixer(MIXERLINE_COMPONENTTYPE_SRC_MICROPHONE, CMixer::Play)
{
}
....


if you have any suggestion or improvement, plz let me know: whoo@isWhoo.com


Whoo
Oct.1 2001