代码非原创：这部分是录制麦克风，其中的重点标记：

https://blog.csdn.net/su_vast/article/details/78318999?utm_source=blogxgwz3
https://blog.csdn.net/lcalqf/article/details/52982550
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#include "stdafx.h"
#include <MMDeviceAPI.h>
#include <AudioClient.h>
#include <AudioPolicy.h>
 
#define MAX_AUDIO_FRAME_SIZE 192000
 
template <class T> void SafeRelease(T **ppT)
{
if (*ppT)
{
    (*ppT)->Release();
    *ppT = NULL;
}
}
 
int _tmain(int argc, _TCHAR* argv[])
{
 
    IAudioClient *      _AudioClient;
    IAudioCaptureClient *_CaptureClient;
    IMMDevice * _Device;
    IMMDeviceEnumerator *deviceEnumerator = NULL;
    HANDLE _AudioSamplesReadyEvent=NULL;
 
    HRESULT hr = CoInitializeEx(NULL, COINIT_MULTITHREADED);
 
    hr = CoCreateInstance(__uuidof(MMDeviceEnumerator), NULL, CLSCTX_INPROC_SERVER, IID_PPV_ARGS(&deviceEnumerator));
    if (FAILED(hr))
    {
        printf("Unable to retrieve CoCreateInstance %x\n", hr);
        goto Exit;
    }
    //这里可以调用EnumAudioEndpoints选择使用其它设备
    hr = deviceEnumerator->GetDefaultAudioEndpoint(eCapture,eMultimedia,&_Device);
    if (FAILED(hr))
    {
        printf("Unable to retrieve device %x\n", hr);
        goto Exit;
    }
    SafeRelease(&deviceEnumerator);
 
    _Device->AddRef();    // Since we‘re holding a copy of the endpoint, take a reference to it.  It‘ll be released in Shutdown();
 
    _AudioSamplesReadyEvent = CreateEventEx(NULL, NULL, 0, EVENT_MODIFY_STATE | SYNCHRONIZE);
    if (_AudioSamplesReadyEvent == NULL)
    {
        printf("Unable to create samples ready event: %d.\n", GetLastError());
        return false;
    }
 
    hr = _Device->Activate(__uuidof(IAudioClient), CLSCTX_INPROC_SERVER, NULL, reinterpret_cast<void **>(&_AudioClient));
    if (FAILED(hr))
    {
        printf("Unable to activate audio client: %x.\n", hr);
        return false;
    }
 
    WAVEFORMATEX *      _MixFormat;
    UINT32              _BufferSize;
    hr = _AudioClient->GetMixFormat(&_MixFormat);
    if (FAILED(hr))
    {
        printf("Unable to get mix format on audio client: %x.\n", hr);
        return false;
    }
 
    size_t _FrameSize = (_MixFormat->wBitsPerSample / 8) * _MixFormat->nChannels;
 
    //InitializeAudioEngine
    hr = _AudioClient->Initialize(AUDCLNT_SHAREMODE_SHARED, AUDCLNT_STREAMFLAGS_EVENTCALLBACK | AUDCLNT_STREAMFLAGS_NOPERSIST, 20*10000, 0, _MixFormat, NULL);
 
    if (FAILED(hr))
    {
        printf("Unable to initialize audio client: %x.\n", hr);
        return false;
    }
 
    //
    //  Retrieve the buffer size for the audio client.
    //
    hr = _AudioClient->GetBufferSize(&_BufferSize);
    if(FAILED(hr))
    {
        printf("Unable to get audio client buffer: %x. \n", hr);
        return false;
    }
    hr = _AudioClient->SetEventHandle(_AudioSamplesReadyEvent);
    if (FAILED(hr))
    {
        printf("Unable to set ready event: %x.\n", hr);
        return false;
    }
 
    hr = _AudioClient->GetService(IID_PPV_ARGS(&_CaptureClient));
    if (FAILED(hr))
    {
        printf("Unable to get new capture client: %x.\n", hr);
        return false;
    }
 
    //开始采集
 
    hr = _AudioClient->Start();
    if (FAILED(hr))
    {
        printf("Unable to get new capture client: %x.\n", hr);
        return false;
    }
 
    bool stillPlaying = true;
    while (stillPlaying)
    {
        DWORD waitResult = WaitForSingleObject( _AudioSamplesReadyEvent, INFINITE);
 
        BYTE *pData,*pBuffer;
        INT nBufferLenght;
        UINT32 framesAvailable;
        DWORD  flags;
        pBuffer=new BYTE[MAX_AUDIO_FRAME_SIZE];
        hr = _CaptureClient->GetBuffer(&pData, &framesAvailable, &flags, NULL, NULL);
        if (SUCCEEDED(hr))
        {
            if (framesAvailable!=0)
            {
                if (flags & AUDCLNT_BUFFERFLAGS_SILENT)
                {
                    //
                    //  Fill 0s from the capture buffer to the output buffer.
                    //
                }
                else
                {
                    //
                    //  Copy data from the audio engine buffer to the output buffer.
                    //
 
                    CopyMemory(pBuffer,pData,framesAvailable*_FrameSize);
                    printf("get capture frames: %d!\n", framesAvailable);
                }
            }
            delete[] pBuffer;
            hr = _CaptureClient->ReleaseBuffer(framesAvailable);
            if (FAILED(hr))
            {
                printf("Unable to release capture buffer: %x!\n", hr);
            }
        }
    }
Exit:
 
    return 0;
}

采集扬声器，内部声音录制
#include "stdafx.h"
#include <MMDeviceAPI.h>
#include <AudioClient.h>
#include <AudioPolicy.h>
 
#define MAX_AUDIO_FRAME_SIZE 192000
 
template <class T> void SafeRelease(T **ppT)
{
if (*ppT)
{
    (*ppT)->Release();
    *ppT = NULL;
}
}
 
int _tmain(int argc, _TCHAR* argv[])
{
 
    IAudioClient *      _AudioClient;
    IAudioCaptureClient *_CaptureClient;
    IMMDevice * _Device;
    IMMDeviceEnumerator *deviceEnumerator = NULL;
    HANDLE _AudioSamplesReadyEvent=NULL;
 
    HRESULT hr = CoInitializeEx(NULL, COINIT_MULTITHREADED);
 
    hr = CoCreateInstance(__uuidof(MMDeviceEnumerator), NULL, CLSCTX_ALL, IID_PPV_ARGS(&deviceEnumerator));
    if (FAILED(hr))
    {
        printf("Unable to retrieve CoCreateInstance %x\n", hr);
        goto Exit;
    }
    //这里可以调用EnumAudioEndpoints选择使用其它设备
    hr = deviceEnumerator->GetDefaultAudioEndpoint(eRENDER,eMultimedia,&_Device);
    if (FAILED(hr))
    {
        printf("Unable to retrieve device %x\n", hr);
        goto Exit;
    }
    SafeRelease(&deviceEnumerator);
 
    _Device->AddRef();    // Since we‘re holding a copy of the endpoint, take a reference to it.  It‘ll be released in Shutdown();
 
    _AudioSamplesReadyEvent = CreateEventEx(NULL, NULL, 0, EVENT_MODIFY_STATE | SYNCHRONIZE);
    if (_AudioSamplesReadyEvent == NULL)
    {
        printf("Unable to create samples ready event: %d.\n", GetLastError());
        return false;
    }
 
    hr = _Device->Activate(__uuidof(IAudioClient), CLSCTX_ALL, NULL, reinterpret_cast<void **>(&_AudioClient));
    if (FAILED(hr))
    {
        printf("Unable to activate audio client: %x.\n", hr);
        return false;
    }
 
    WAVEFORMATEX *      _MixFormat;
    UINT32              _BufferSize;
    hr = _AudioClient->GetMixFormat(&_MixFormat);
    if (FAILED(hr))
    {
        printf("Unable to get mix format on audio client: %x.\n", hr);
        return false;
    }
 
    size_t _FrameSize = (_MixFormat->wBitsPerSample / 8) * _MixFormat->nChannels;
 
    //InitializeAudioEngine
    hr = _AudioClient->Initialize(AUDCLNT_SHAREMODE_SHARED, AUDCLNT_STREAMFLAGS_LOOPBACK, 20*10000, 0, _MixFormat, NULL);
 
    if (FAILED(hr))
    {
        printf("Unable to initialize audio client: %x.\n", hr);
        return false;
    }
 
    //
    //  Retrieve the buffer size for the audio client.
    //
    hr = _AudioClient->GetBufferSize(&_BufferSize);
    if(FAILED(hr))
    {
        printf("Unable to get audio client buffer: %x. \n", hr);
        return false;
    }

   /*不需要 hr = _AudioClient->SetEventHandle(_AudioSamplesReadyEvent);
    if (FAILED(hr))
    {
        printf("Unable to set ready event: %x.\n", hr);
        return false;
    }*/
 
    hr = _AudioClient->GetService(IID_PPV_ARGS(&_CaptureClient));
    if (FAILED(hr))
    {
        printf("Unable to get new capture client: %x.\n", hr);
        return false;
    }
 
    //开始采集
 
    hr = _AudioClient->Start();
    if (FAILED(hr))
    {
        printf("Unable to get new capture client: %x.\n", hr);
        return false;
    }
 
    bool stillPlaying = true;
    while (stillPlaying)
    {
        // 内部录制不需要 DWORD waitResult = WaitForSingleObject( _AudioSamplesReadyEvent, INFINITE);
        //注意存在一次拿不干净的情况，尤其是上头有阻塞。
        //以及某些机器，没有内部声音的时候，拿到的是全0 ，但有些机器是拿不到任何数据的
        BYTE *pData,*pBuffer;
        INT nBufferLenght;
        UINT32 framesAvailable;
        DWORD  flags;
        pBuffer=new BYTE[MAX_AUDIO_FRAME_SIZE];
        hr = _CaptureClient->GetBuffer(&pData, &framesAvailable, &flags, NULL, NULL);
        if (SUCCEEDED(hr))
        {
            if (framesAvailable!=0)
            {
                if (flags & AUDCLNT_BUFFERFLAGS_SILENT)
                {
                    //
                    //  Fill 0s from the capture buffer to the output buffer.
                    //
                }
                else
                {
                    //
                    //  Copy data from the audio engine buffer to the output buffer.
                    //
 
                    CopyMemory(pBuffer,pData,framesAvailable*_FrameSize);
                    printf("get capture frames: %d!\n", framesAvailable);
                }
            }
            delete[] pBuffer;
            hr = _CaptureClient->ReleaseBuffer(framesAvailable);
            if (FAILED(hr))
            {
                printf("Unable to release capture buffer: %x!\n", hr);
            }
        }
    }
Exit:
 
    return 0;
}