如何以编程方式设置应用程序的默认输入和输出音频设备？

Question

If I go to Settings on a Windows 10 (1803) computer, I have access to a page ("App Volume and Device Preferences") that lets me set the default input and output device for a running application.

How can I set these options programmatically?

Related:

• Set audio endpoint devices application specific (programmatically)
  Seems to refer to a more specific problem, and is unanswered.
• Controlling “App volume and device preferences” menu, from settings, with python 3.6, or any language(Windows). Automatic App audio device switching
  Too broad, wrong site.
• IAudioSessionControl2 and related family
  Allows reading the device and setting volume and mute, but doesn't seem to allow changing the device
• GitHub issue page for SoundSwitch also looking for API
  Implies API is undocumented by design (default device being controlled by user)

Answer 1

Here you can enumerate all the playback devices

#include <windows.h>
#include <mmsystem.h>
#include <iostream>
using namespace std;
#pragma comment(lib, "Winmm.lib")

int main()
{
    int nSoundCardCount = waveOutGetNumDevs();

    for (int i = 0; i < nSoundCardCount; i++)
    {
        WAVEOUTCAPS woc;
        waveOutGetDevCaps(i, &woc, sizeof(woc));

        cout << woc.szPname << endl; 
    }

    system("pause");
    return 0;
}

---

Here you need to use PolicyConfig.h and SetDefaultAudioPlaybackDevice to add .h files and interfaces. Refer to this project

1.Add the header file PolicyConfig.h

2.Add the head file and interface.

#include "Mmdeviceapi.h"
#include "PolicyConfig.h"
#include "Propidl.h"
#include "Functiondiscoverykeys_devpkey.h"

HRESULT SetDefaultAudioPlaybackDevice( LPCWSTR devID )
{
    IPolicyConfigVista *pPolicyConfig;
    ERole reserved = eConsole;

    HRESULT hr = CoCreateInstance(__uuidof(CPolicyConfigVistaClient), 
        NULL, CLSCTX_ALL, __uuidof(IPolicyConfigVista), (LPVOID *)&pPolicyConfig);
    if (SUCCEEDED(hr))
    {
        hr = pPolicyConfig->SetDefaultEndpoint(devID, reserved);
        pPolicyConfig->Release();
    }
    return hr;
}

3.Use the above interface to write a function to set the default output device.

It's MFC Project. Maybe you need to change.

Which output device needs to be set, you can modify the content of the macro yourself. I get the name of output device using waveOutGetDevCaps()

//Set the default audio playback device 
#define  DEF_AUDIO_NAME _T("Speakers (2- Logitech USB Heads")  //modify it, my device is Speakers (2- Logitech USB Heads

void InitDefaultAudioDevice()
{
    HRESULT hr = CoInitialize(NULL);
    if (SUCCEEDED(hr))
    {
        IMMDeviceEnumerator *pEnum = NULL;
        // Create a multimedia device enumerator.
        hr = CoCreateInstance(__uuidof(MMDeviceEnumerator), NULL,
            CLSCTX_ALL, __uuidof(IMMDeviceEnumerator), (void**)&pEnum);
        if (SUCCEEDED(hr))
        {
            //Determine if it is the default audio device
            bool bExit = false;
            IMMDevice  *pDefDevice = NULL;
            hr = pEnum->GetDefaultAudioEndpoint(eRender, eMultimedia,&pDefDevice);
            if (SUCCEEDED(hr))
            {
                IPropertyStore *pStore;
                hr = pDefDevice->OpenPropertyStore(STGM_READ, &pStore);
                if (SUCCEEDED(hr))
                {
                    PROPVARIANT friendlyName;
                    PropVariantInit(&friendlyName);
                    hr = pStore->GetValue(PKEY_Device_FriendlyName, &friendlyName);
                    if (SUCCEEDED(hr))
                    {
                        CString strTmp = friendlyName.pwszVal;
                        if (strTmp.Find(DEF_AUDIO_NAME) != -1)
                        {
                            bExit = true;
                        }
                        PropVariantClear(&friendlyName);
                    }
                    pStore->Release();
                }
                pDefDevice->Release();
            }
            if (bExit)
            {
                pEnum->Release();
                return;
            }

            IMMDeviceCollection *pDevices;
            // Enumerate the output devices.
            hr = pEnum->EnumAudioEndpoints(eRender, DEVICE_STATE_ACTIVE, &pDevices);
            if (SUCCEEDED(hr))
            {
                UINT count;
                pDevices->GetCount(&count);
                if (SUCCEEDED(hr))
                {
                    for (int i = 0; i < count; i++)
                    {
                        bool bFind = false;
                        IMMDevice *pDevice;
                        hr = pDevices->Item(i, &pDevice);
                        if (SUCCEEDED(hr))
                        {
                            LPWSTR wstrID = NULL;
                            hr = pDevice->GetId(&wstrID);
                            if (SUCCEEDED(hr))
                            {
                                IPropertyStore *pStore;
                                hr = pDevice->OpenPropertyStore(STGM_READ, &pStore);
                                if (SUCCEEDED(hr))
                                {
                                    PROPVARIANT friendlyName;
                                    PropVariantInit(&friendlyName);
                                    hr = pStore->GetValue(PKEY_Device_FriendlyName, &friendlyName);
                                    if (SUCCEEDED(hr))
                                    {
                                        // if no options, print the device
                                        // otherwise, find the selected device and set it to be default
                                        CString strTmp = friendlyName.pwszVal;
                                        if (strTmp.Find(DEF_AUDIO_NAME) != -1)
                                        {
                                            SetDefaultAudioPlaybackDevice(wstrID);
                                            bFind = true;
                                        }
                                        PropVariantClear(&friendlyName);
                                    }
                                    pStore->Release();
                                }
                            }
                            pDevice->Release();
                        }

                        if (bFind)
                        {
                            break;
                        }
                    }
                }
                pDevices->Release();
            }
            pEnum->Release();
        }
    }
    CoUninitialize();
}

This sample can only change the output of Master volume. I don't know whether it can meet your requirements? If you need to change other apps, you have to explore for a while.

Answer 2

So I have been using SoundVolumeView for a while that let me mute and unmute my mic for meeting with a command line and I have discovered recently (because of OBS and monitoring audio) that it can also change device for an app or global default device

• http://www.nirsoft.net/utils/sound_volume_view.html

And using /SetDefault and /SetAppDefault as shown in the doc example to the bottom of the page

I have put that in a batch script and bind a macro to my keyboard and it's doing a good job so far :)