From 837d713edffdddce39ede0f86409c1adac92cc73 Mon Sep 17 00:00:00 2001
From: Guanzhong Chen <quantum2048@gmail.com>
Date: Wed, 8 Jan 2020 23:17:05 -0800
Subject: [PATCH] Handle default output device change by capturing from new
device (#2)
---
winscap.cpp | 130 ++++++++++++++++++++++++++++++++++++----------------
1 file changed, 91 insertions(+), 39 deletions(-)
diff --git a/winscap.cpp b/winscap.cpp
index e0cdf4a..4c7286a 100644
--- a/winscap.cpp
+++ b/winscap.cpp
@@ -32,6 +32,44 @@ _COM_SMARTPTR_TYPEDEF(IMMDevice, __uuidof(IMMDevice));
_COM_SMARTPTR_TYPEDEF(IAudioClient, __uuidof(IAudioClient));
_COM_SMARTPTR_TYPEDEF(IAudioCaptureClient, __uuidof(IAudioCaptureClient));
+class DeviceChangeNotification : public IMMNotificationClient {
+ volatile ULONG ref;
+ volatile bool &changed;
+
+ public:
+ DeviceChangeNotification(volatile bool &changed) : changed(changed) {}
+
+ // This is meant to be allocated on stack, so we don't actually free.
+ STDMETHODIMP_(ULONG) AddRef() { return InterlockedIncrement(&ref); }
+ STDMETHODIMP_(ULONG) Release() { return InterlockedDecrement(&ref); }
+
+ STDMETHODIMP QueryInterface(REFIID iid, void **ppv) {
+ if (iid == IID_IUnknown) {
+ AddRef();
+ *ppv = (IUnknown *)this;
+ } else if (iid == __uuidof(IMMNotificationClient)) {
+ AddRef();
+ *ppv = (IMMNotificationClient *)this;
+ } else {
+ *ppv = nullptr;
+ return E_NOINTERFACE;
+ }
+ return S_OK;
+ }
+
+ STDMETHODIMP OnDefaultDeviceChanged(EDataFlow flow, ERole role, LPCWSTR) {
+ if (flow == eRender && role == eConsole) {
+ changed = true;
+ }
+ return S_OK;
+ }
+
+ STDMETHODIMP OnDeviceAdded(LPCWSTR) { return S_OK; }
+ STDMETHODIMP OnDeviceRemoved(LPCWSTR) { return S_OK; }
+ STDMETHODIMP OnDeviceStateChanged(LPCWSTR, DWORD) { return S_OK; }
+ STDMETHODIMP OnPropertyValueChanged(LPCWSTR, const PROPERTYKEY) { return S_OK; }
+};
+
class EnsureCaptureStop {
IAudioClientPtr m_client;
@@ -99,15 +137,6 @@ int main(int argc, char *argv[]) {
CCoInitialize comInit;
ensure(comInit);
- IMMDeviceEnumeratorPtr pEnumerator;
- ensure(pEnumerator.CreateInstance(__uuidof(MMDeviceEnumerator)));
-
- IMMDevicePtr pDevice;
- ensure(pEnumerator->GetDefaultAudioEndpoint(eRender, eConsole, &pDevice));
-
- IAudioClientPtr pClient;
- ensure(pDevice->Activate(__uuidof(IAudioClient), CLSCTX_ALL, nullptr, (void **)&pClient));
-
WAVEFORMATEX wfx;
wfx.wFormatTag = WAVE_FORMAT_PCM;
wfx.nChannels = (WORD)channels;
@@ -116,44 +145,67 @@ int main(int argc, char *argv[]) {
wfx.nBlockAlign = wfx.nChannels * wfx.wBitsPerSample / 8;
wfx.nAvgBytesPerSec = wfx.nSamplesPerSec * wfx.nBlockAlign;
- ensure(pClient->Initialize(AUDCLNT_SHAREMODE_SHARED, AUDCLNT_STREAMFLAGS_LOOPBACK,
- 16 * REFTIMES_PER_MILLISEC, 0, &wfx, nullptr));
+ IMMDeviceEnumeratorPtr pEnumerator;
+ ensure(pEnumerator.CreateInstance(__uuidof(MMDeviceEnumerator)));
- UINT32 bufferFrameCount;
- ensure(pClient->GetBufferSize(&bufferFrameCount));
-
- IAudioCaptureClientPtr pCapture;
- ensure(pClient->GetService(__uuidof(IAudioCaptureClient), (void **)&pCapture));
-
- DWORD dwDelay = (DWORD)(((double)REFTIMES_PER_SEC * bufferFrameCount / wfx.nSamplesPerSec) /
- REFTIMES_PER_MILLISEC / 2);
-
- LPBYTE pSilence = (LPBYTE)malloc(bufferFrameCount * wfx.nBlockAlign);
- EnsureFree freeSilence(pSilence);
- ZeroMemory(pSilence, bufferFrameCount * wfx.nBlockAlign);
-
- ensure(pClient->Start());
- EnsureCaptureStop autoStop(pClient);
+ volatile bool deviceChanged = false;
+ DeviceChangeNotification deviceChangeNotification(deviceChanged);
+ pEnumerator->RegisterEndpointNotificationCallback(&deviceChangeNotification);
for (;;) {
- Sleep(dwDelay);
+ IMMDevicePtr pDevice;
+ ensure(pEnumerator->GetDefaultAudioEndpoint(eRender, eConsole, &pDevice));
- UINT32 packetLength;
- ensure(pCapture->GetNextPacketSize(&packetLength));
+ IAudioClientPtr pClient;
+ ensure(pDevice->Activate(__uuidof(IAudioClient), CLSCTX_ALL, nullptr, (void **)&pClient));
- while (packetLength) {
- LPBYTE pData;
- UINT32 numFramesAvailable;
- DWORD flags;
+ ensure(pClient->Initialize(AUDCLNT_SHAREMODE_SHARED, AUDCLNT_STREAMFLAGS_LOOPBACK,
+ 16 * REFTIMES_PER_MILLISEC, 0, &wfx, nullptr));
- ensure(pCapture->GetBuffer(&pData, &numFramesAvailable, &flags, nullptr, nullptr));
+ UINT32 bufferFrameCount;
+ ensure(pClient->GetBufferSize(&bufferFrameCount));
- if (flags & AUDCLNT_BUFFERFLAGS_SILENT)
- pData = pSilence;
+ IAudioCaptureClientPtr pCapture;
+ ensure(pClient->GetService(__uuidof(IAudioCaptureClient), (void **)&pCapture));
- _write(_fileno(stdout), pData, wfx.nBlockAlign * numFramesAvailable);
- ensure(pCapture->ReleaseBuffer(numFramesAvailable));
- ensure(pCapture->GetNextPacketSize(&packetLength));
+ DWORD dwDelay = (DWORD)(((double)REFTIMES_PER_SEC * bufferFrameCount / wfx.nSamplesPerSec) /
+ REFTIMES_PER_MILLISEC / 2);
+
+ LPBYTE pSilence = (LPBYTE)malloc(bufferFrameCount * wfx.nBlockAlign);
+ EnsureFree freeSilence(pSilence);
+ ZeroMemory(pSilence, bufferFrameCount * wfx.nBlockAlign);
+
+ ensure(pClient->Start());
+ EnsureCaptureStop autoStop(pClient);
+
+ while (!deviceChanged) {
+ Sleep(dwDelay);
+
+ UINT32 packetLength;
+ HRESULT hrNext = pCapture->GetNextPacketSize(&packetLength);
+ if (hrNext == AUDCLNT_E_DEVICE_INVALIDATED) {
+ while (!deviceChanged)
+ ;
+ break;
+ } else {
+ ensure(hrNext);
+ }
+
+ while (packetLength) {
+ LPBYTE pData;
+ UINT32 numFramesAvailable;
+ DWORD flags;
+
+ ensure(pCapture->GetBuffer(&pData, &numFramesAvailable, &flags, nullptr, nullptr));
+
+ if (flags & AUDCLNT_BUFFERFLAGS_SILENT)
+ pData = pSilence;
+
+ _write(_fileno(stdout), pData, wfx.nBlockAlign * numFramesAvailable);
+ ensure(pCapture->ReleaseBuffer(numFramesAvailable));
+ ensure(pCapture->GetNextPacketSize(&packetLength));
+ }
}
+ deviceChanged = false;
}
}