Detect the Audio And Microphone Level In Windows

**Kelderic** · 11-17-2009

Thank you all for the help. I'm sorry if it is in the wrong forum, I'm trying to write it in C, so I thought this was the place. Looking through the links provided, I'm finding several functions that are what I need, but I keep getting the save error message. I have try testing code that others have written, and even the finished versions give me the same error, so I'm a bit confused.

Code:

#include<stdio.h>
#include<Windows.h>


int main()
{
  int NumMixers = mixerGetNumDevs();
  int volume;
  volume = auxGetVolume(UINT,PDWORD);
  while(6)
  {
    NumMixers = mixerGetNumDevs();
    printf("%d\n",volume);
    Sleep(100);
  }
  getch();
  return(0);
}

I know there is a syntax error with the auxGetVolume, but even with the mixerGetNumDevs, it's saying " [Linker error] undefined reference to `mixerGetNumDevs@0' "

**BobS0327** · 11-17-2009

I know there is a syntax error with the auxGetVolume, but even with the mixerGetNumDevs, it's saying " [Linker error] undefined reference to `mixerGetNumDevs@0' "

Link with Winmm.lib

**arpsmack** · 11-18-2009

Here's a small app I wrote years ago. Some of the comments look a little fishy, and I'm not even sure it's entirely correct, but it does seem to work for me.

Code:

#include <windows.h>

/*^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 * A small commandline tool to check the volume set on the speaker out line of
 * the primary/default sound card mixer device.
 * 
 * Basically, it prints out the master audio volume for the system.
 *vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
 */    
int main(int argc, char ** argv) {
  HMIXER mixerHandle;
  MIXERCAPS mixcaps;
  MIXERLINE mixerline;
  MIXERCONTROL volumeControl;
  MIXERLINECONTROLS mixerLineControls;
  MIXERCONTROLDETAILS_UNSIGNED value;
  MIXERCONTROLDETAILS mixerControlDetails;
  
  // Open the mixer associated with the default sound card in the computer
  if (mixerOpen(&mixerHandle, 0, 0, 0, 0)) {
      printf("Couldn't open mixer\n");
  }
  else {
    // Get info about the first Mixer Device
    if (mixerGetDevCaps((UINT)mixerHandle, &mixcaps, sizeof(MIXERCAPS))) {
      printf("Error calling mixerGetDevCaps()\n");
    }
    else {
      printf("Sound Card:  %s\n", mixcaps.szPname);
      printf("There are %d supported destinations for this card\n", mixcaps.cDestinations);
      printf("\nFetching info about the speaker line out:\n");
      
      mixerline.cbStruct = sizeof(MIXERLINE);
      mixerline.dwComponentType = MIXERLINE_COMPONENTTYPE_DST_SPEAKERS;
        
      // Get info about the speaker destination line
      if (mixerGetLineInfo((HMIXEROBJ)mixerHandle, &mixerline, MIXER_GETLINEINFOF_COMPONENTTYPE)) {
        printf("Error getting speakers line info\n");
      }
      else {
        printf("  Name:         %s\n", mixerline.szShortName);
        printf("  Description:  %s\n", mixerline.szName);
        
        mixerLineControls.cbStruct = sizeof(MIXERLINECONTROLS);
        mixerLineControls.dwLineID = mixerline.dwLineID;
        mixerLineControls.dwControlType = MIXERCONTROL_CONTROLTYPE_VOLUME;
        mixerLineControls.cControls = 1;
        mixerLineControls.pamxctrl = &volumeControl;
        mixerLineControls.cbmxctrl = sizeof(MIXERCONTROL);
        
        // Get info about the speaker line's volume control
        if (mixerGetLineControls((HMIXEROBJ)mixerHandle, &mixerLineControls, MIXER_GETLINECONTROLSF_ONEBYTYPE)) {
          printf("Couldn't get info about the speaker line's volume control\n");
        }
        else {
          mixerControlDetails.cbStruct = sizeof(MIXERCONTROLDETAILS);
          mixerControlDetails.dwControlID = volumeControl.dwControlID;
          mixerControlDetails.cChannels = 1;
          mixerControlDetails.cMultipleItems = volumeControl.cMultipleItems;
          mixerControlDetails.paDetails = &value;
          mixerControlDetails.cbDetails = sizeof(MIXERCONTROLDETAILS_UNSIGNED);
          
          // Get the value of the speaker line's volume control
          if (mixerGetControlDetails((HMIXEROBJ)mixerHandle, &mixerControlDetails, MIXER_GETCONTROLDETAILSF_VALUE)) {
            printf("Couldn't get speaker line's volume control details\n");
          }
          else {
            printf("Speaker line's volume is set to %u (%d%%)\n", value.dwValue,
                     (int)((double)value.dwValue/volumeControl.Bounds.dwMaximum*100));
          }
        }
      }
    }
  }
  
  printf("Closing mixer device's handle\n");
  mixerClose(mixerHandle);
}

And here's a sample output running it once on my machine, increasing my system volume a bit, and then running it again:

Code:

Z:\>mixer
Sound Card:  Realtek HD Audio output
There are 1 supported destinations for this card

Fetching info about the speaker line out:
  Name:         Master Volume
  Description:  Master Volume
Speaker line's volume is set to 7864 (11%)
Closing mixer device's handle

Z:\>mixer
Sound Card:  Realtek HD Audio output
There are 1 supported destinations for this card

Fetching info about the speaker line out:
  Name:         Master Volume
  Description:  Master Volume
Speaker line's volume is set to 15728 (23%)
Closing mixer device's handle

I know they revamped the audio APIs when Vista came out. Obviously the mixer API is still there, but its been reimplemented on top of whatever it is that Vista uses now. If I remember right, the changes make it harder to get the actual "system volume" since a lot of the volume settings are per application in Vista. I know I wrote a version of my app that works in Vista, so I'll see if I can't dig up an example for that as well.

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