wasapi: Refactored audio client instance creation by joining separate versions for input/output, removed unused code related to IAudioEndpointVolume, added comment about enforced double buffering on PA WASAPI side inside _CalculateFramesPerHostBuffer(). (#773)

1) Refactored audio client instance creation by joining separate versions for input/output.
2) Removed unused code related to `IAudioEndpointVolume`.
3) Left comment about double buffering on PA WASAPI side inside `_CalculateFramesPerHostBuffer`.
4) Removed unused jitter margin calculation in _GetFramesPerHostBuffer.

Change 1. makes implementation more compact.

Change 2. removed `IAudioEndpointVolume` related code which was always unused by PA implementation.

Change 3. does not change PA WASAPI behavior, it just adds the comment about enforced double buffering.

Change 4. does not change behavior because it was always adding 0.

Author: dmitrykos

src/hostapi/wasapi/pa_win_wasapi.c

@@ -1,7 +1,7 @@
 /*
  * Portable Audio I/O Library WASAPI implementation
  * Copyright (c) 2006-2010 David Viens
- * Copyright (c) 2010-2022 Dmitry Kostjuchenko
+ * Copyright (c) 2010-2023 Dmitry Kostjuchenko
  *
  * Based on the Open Source API proposed by Ross Bencina
  * Copyright (c) 1999-2019 Ross Bencina, Phil Burk
@@ -584,7 +584,6 @@ typedef struct PaWasapiStream
     IStream                   *captureClientStream;
 #endif
     IAudioCaptureClient       *captureClient;
-    IAudioEndpointVolume      *inVol;
 
     // output
     PaWasapiSubStream          out;
@@ -593,7 +592,6 @@ typedef struct PaWasapiStream
     IStream                   *renderClientStream;
 #endif
     IAudioRenderClient        *renderClient;
-    IAudioEndpointVolume      *outVol;
 
     // Event handles for event-driven processing mode
     HANDLE event[S_COUNT];
@@ -3304,11 +3302,14 @@ static PaError IsFormatSupported( struct PaUtilHostApiRepresentation *hostApi,
 }
 
 // ------------------------------------------------------------------------------------------
-static PaUint32 _GetFramesPerHostBuffer(PaUint32 userFramesPerBuffer, PaTime suggestedLatency, double sampleRate, PaUint32 TimerJitterMs)
+static UINT32 _CalculateFramesPerHostBuffer(UINT32 userFramesPerBuffer, PaTime suggestedLatency, double sampleRate)
 {
-    PaUint32 frames = userFramesPerBuffer + max( userFramesPerBuffer, (PaUint32)(suggestedLatency * sampleRate) );
-    frames += (PaUint32)((sampleRate * 0.001) * TimerJitterMs);
-    return frames;
+    // Note: WASAPI tends to enforce double buffering by itself therefore enforcing double buffering
+    // on PA side looks as an excessive measure.
+    const BOOL doubleBuffering = TRUE;
+
+    return userFramesPerBuffer + max((doubleBuffering ? userFramesPerBuffer : 0),
+        (UINT32)(suggestedLatency * sampleRate));
 }
 
 // ------------------------------------------------------------------------------------------
@@ -3323,15 +3324,15 @@ static void _RecalculateBuffersCount(PaWasapiSubStream *sub, UINT32 userFramesPe
     // Determine number of buffers used:
     // - Full-duplex mode will lead to period difference, thus only 1
     // - Input mode, only 1, as WASAPI allows extraction of only 1 packet
-    // - For Shared mode we use double buffering
+    // - For Shared mode we use double buffering (see _CalculateFramesPerHostBuffer)
     if ((sub->shareMode == AUDCLNT_SHAREMODE_EXCLUSIVE) || fullDuplex)
     {
         BOOL eventMode = ((sub->streamFlags & AUDCLNT_STREAMFLAGS_EVENTCALLBACK) == AUDCLNT_STREAMFLAGS_EVENTCALLBACK);
 
         // Exclusive mode does not allow >1 buffers be used for Event interface, e.g. GetBuffer
         // call must acquire max buffer size and it all must be processed.
         if (eventMode)
-            sub->userBufferAndHostMatch = 1;
+            sub->userBufferAndHostMatch = TRUE;
 
         // Full-duplex or Event mode: prefer paUtilBoundedHostBufferSize because exclusive mode will starve
         // and produce glitchy audio
@@ -3468,9 +3469,8 @@ static HRESULT CreateAudioClient(PaWasapiStream *pStream, PaWasapiSubStream *pSu
     if ((pSub->shareMode != AUDCLNT_SHAREMODE_EXCLUSIVE) &&
         (!pSub->streamFlags || ((pSub->streamFlags & AUDCLNT_STREAMFLAGS_EVENTCALLBACK) == 0)))
     {
-        framesPerLatency = _GetFramesPerHostBuffer(userFramesPerBuffer,
-            params->suggestedLatency, pSub->wavex.Format.nSamplesPerSec, 0/*,
-            (pSub->streamFlags & AUDCLNT_STREAMFLAGS_EVENTCALLBACK ? 0 : 1)*/);
+        framesPerLatency = _CalculateFramesPerHostBuffer(userFramesPerBuffer, params->suggestedLatency,
+            pSub->wavex.Format.nSamplesPerSec);
     }
     else
     {
@@ -3487,9 +3487,8 @@ static HRESULT CreateAudioClient(PaWasapiStream *pStream, PaWasapiSubStream *pSu
         overall = MakeHnsPeriod(framesPerLatency, pSub->wavex.Format.nSamplesPerSec);
         if (overall >= (106667 * 2)/*21.33ms*/)
         {
-            framesPerLatency = _GetFramesPerHostBuffer(userFramesPerBuffer,
-                params->suggestedLatency, pSub->wavex.Format.nSamplesPerSec, 0/*,
-                (streamFlags & AUDCLNT_STREAMFLAGS_EVENTCALLBACK ? 0 : 1)*/);
+            framesPerLatency = _CalculateFramesPerHostBuffer(userFramesPerBuffer, params->suggestedLatency,
+                pSub->wavex.Format.nSamplesPerSec);
 
             // Use Polling interface
             pSub->streamFlags &= ~AUDCLNT_STREAMFLAGS_EVENTCALLBACK;
@@ -3753,123 +3752,64 @@ static HRESULT CreateAudioClient(PaWasapiStream *pStream, PaWasapiSubStream *pSu
 }
 
 // ------------------------------------------------------------------------------------------
-static PaError ActivateAudioClientOutput(PaWasapiStream *stream)
-{
-    HRESULT hr;
-    PaError result;
-    UINT32 maxBufferSize;
-    PaTime bufferLatency;
-    const UINT32 framesPerBuffer = stream->out.params.frames_per_buffer;
-
-    // Create Audio client
-    if (FAILED(hr = CreateAudioClient(stream, &stream->out, TRUE, &result)))
-    {
-        LogPaError(result);
-        goto error;
-    }
-    LogWAVEFORMATEXTENSIBLE(&stream->out.wavex);
-
-    // Activate volume
-    stream->outVol = NULL;
-    /*hr = info->device->Activate(
-        __uuidof(IAudioEndpointVolume), CLSCTX_INPROC_SERVER, NULL,
-        (void**)&stream->outVol);
-    if (hr != S_OK)
-        return paInvalidDevice;*/
-
-    // Get max possible buffer size to check if it is not less than that we request
-    if (FAILED(hr = IAudioClient_GetBufferSize(stream->out.clientParent, &maxBufferSize)))
-    {
-        LogHostError(hr);
-        LogPaError(result = paInvalidDevice);
-        goto error;
-    }
-
-    // Correct buffer to max size if it maxed out result of GetBufferSize
-    stream->out.bufferSize = maxBufferSize;
-
-    // Number of frames that are required at each period
-    stream->out.framesPerHostCallback = maxBufferSize;
-
-    // Calculate frames per single buffer, if buffers > 1 then always framesPerBuffer
-    stream->out.framesPerBuffer =
-        (stream->out.userBufferAndHostMatch ? stream->out.framesPerHostCallback : framesPerBuffer);
-
-    // Calculate buffer latency
-    bufferLatency = (PaTime)maxBufferSize / stream->out.wavex.Format.nSamplesPerSec;
-
-    // Append buffer latency to interface latency in shared mode (see GetStreamLatency notes)
-    stream->out.latencySeconds = bufferLatency;
-
-    PRINT(("WASAPI::OpenStream(output): framesPerUser[ %d ] framesPerHost[ %d ] latency[ %.02fms ] exclusive[ %s ] wow64_fix[ %s ] mode[ %s ]\n", (UINT32)framesPerBuffer, (UINT32)stream->out.framesPerHostCallback, (float)(stream->out.latencySeconds*1000.0f), (stream->out.shareMode == AUDCLNT_SHAREMODE_EXCLUSIVE ? "YES" : "NO"), (stream->out.params.wow64_workaround ? "YES" : "NO"), (stream->out.streamFlags & AUDCLNT_STREAMFLAGS_EVENTCALLBACK ? "EVENT" : "POLL")));
-
-    return paNoError;
-
-error:
-
-    return result;
-}
-
-// ------------------------------------------------------------------------------------------
-static PaError ActivateAudioClientInput(PaWasapiStream *stream)
+static PaError ActivateAudioClient(PaWasapiStream *stream, BOOL output)
 {
     HRESULT hr;
     PaError result;
     UINT32 maxBufferSize;
     PaTime bufferLatency;
-    const UINT32 framesPerBuffer = stream->in.params.frames_per_buffer;
+    PaWasapiSubStream *subStream = (output ? &stream->out : &stream->in);
 
     // Create Audio client
-    if (FAILED(hr = CreateAudioClient(stream, &stream->in, FALSE, &result)))
+    if (FAILED(hr = CreateAudioClient(stream, subStream, output, &result)))
     {
         LogPaError(result);
         goto error;
     }
-    LogWAVEFORMATEXTENSIBLE(&stream->in.wavex);
-
-    // Create volume mgr
-    stream->inVol = NULL;
-    /*hr = info->device->Activate(
-        __uuidof(IAudioEndpointVolume), CLSCTX_INPROC_SERVER, NULL,
-        (void**)&stream->inVol);
-    if (hr != S_OK)
-        return paInvalidDevice;*/
+    LogWAVEFORMATEXTENSIBLE(&subStream->wavex);
 
     // Get max possible buffer size to check if it is not less than that we request
-    if (FAILED(hr = IAudioClient_GetBufferSize(stream->in.clientParent, &maxBufferSize)))
+    if (FAILED(hr = IAudioClient_GetBufferSize(subStream->clientParent, &maxBufferSize)))
     {
         LogHostError(hr);
         LogPaError(result = paInvalidDevice);
         goto error;
     }
 
     // Correct buffer to max size if it maxed out result of GetBufferSize
-    stream->in.bufferSize = maxBufferSize;
+    subStream->bufferSize = maxBufferSize;
 
-    // Get interface latency (actually unneeded as we calculate latency from the size
-    // of maxBufferSize).
-    if (FAILED(hr = IAudioClient_GetStreamLatency(stream->in.clientParent, &stream->in.deviceLatency)))
+    if (!output)
     {
-        LogHostError(hr);
-        LogPaError(result = paInvalidDevice);
-        goto error;
+        // Get interface latency (actually unneeded as we calculate latency from the size of maxBufferSize)
+        if (FAILED(hr = IAudioClient_GetStreamLatency(stream->in.clientParent, &stream->in.deviceLatency)))
+        {
+            LogHostError(hr);
+            LogPaError(result = paInvalidDevice);
+            goto error;
+        }
+        //stream->in.latencySeconds = nano100ToSeconds(stream->in.deviceLatency);
     }
-    //stream->in.latencySeconds = nano100ToSeconds(stream->in.deviceLatency);
 
     // Number of frames that are required at each period
-    stream->in.framesPerHostCallback = maxBufferSize;
+    subStream->framesPerHostCallback = maxBufferSize;
 
     // Calculate frames per single buffer, if buffers > 1 then always framesPerBuffer
-    stream->in.framesPerBuffer =
-        (stream->in.userBufferAndHostMatch ? stream->in.framesPerHostCallback : framesPerBuffer);
+    subStream->framesPerBuffer = (subStream->userBufferAndHostMatch ?
+        subStream->framesPerHostCallback : subStream->params.frames_per_buffer);
 
     // Calculate buffer latency
-    bufferLatency = (PaTime)maxBufferSize / stream->in.wavex.Format.nSamplesPerSec;
+    bufferLatency = (PaTime)maxBufferSize / subStream->wavex.Format.nSamplesPerSec;
 
     // Append buffer latency to interface latency in shared mode (see GetStreamLatency notes)
-    stream->in.latencySeconds = bufferLatency;
+    subStream->latencySeconds = bufferLatency;
 
-    PRINT(("WASAPI::OpenStream(input): framesPerUser[ %d ] framesPerHost[ %d ] latency[ %.02fms ] exclusive[ %s ] wow64_fix[ %s ] mode[ %s ]\n", (UINT32)framesPerBuffer, (UINT32)stream->in.framesPerHostCallback, (float)(stream->in.latencySeconds*1000.0f), (stream->in.shareMode == AUDCLNT_SHAREMODE_EXCLUSIVE ? "YES" : "NO"), (stream->in.params.wow64_workaround ? "YES" : "NO"), (stream->in.streamFlags & AUDCLNT_STREAMFLAGS_EVENTCALLBACK ? "EVENT" : "POLL")));
+    PRINT(("WASAPI::OpenStream(%s): framesPerUser[ %d ] framesPerHost[ %d ] latency[ %.02fms ] exclusive[ %s ] wow64_fix[ %s ] mode[ %s ]\n",
+        (output ? "output" : "input"),
+        subStream->params.frames_per_buffer, subStream->framesPerHostCallback, (subStream->latencySeconds * 1000),
+        (subStream->shareMode == AUDCLNT_SHAREMODE_EXCLUSIVE ? "YES" : "NO"),
+        (subStream->params.wow64_workaround ? "YES" : "NO"),
+        (subStream->streamFlags & AUDCLNT_STREAMFLAGS_EVENTCALLBACK ? "EVENT" : "POLL")));
 
     return paNoError;
 
@@ -4025,7 +3965,7 @@ static PaError OpenStream( struct PaUtilHostApiRepresentation *hostApi,
         stream->in.params.wow64_workaround  = paWasapi->useWOW64Workaround;
 
         // Create and activate audio client
-        if ((result = ActivateAudioClientInput(stream)) != paNoError)
+        if ((result = ActivateAudioClient(stream, FALSE)) != paNoError)
         {
             LogPaError(result);
             goto error;
@@ -4158,7 +4098,7 @@ static PaError OpenStream( struct PaUtilHostApiRepresentation *hostApi,
         stream->out.params.wow64_workaround  = paWasapi->useWOW64Workaround;
 
         // Create and activate audio client
-        if ((result = ActivateAudioClientOutput(stream)) != paNoError)
+        if ((result = ActivateAudioClient(stream, TRUE)) != paNoError)
         {
             LogPaError(result);
             goto error;
@@ -4335,8 +4275,6 @@ static PaError CloseStream( PaStream* s )
     SAFE_RELEASE(stream->renderClientParent);
     SAFE_RELEASE(stream->out.clientParent);
     SAFE_RELEASE(stream->in.clientParent);
-    SAFE_RELEASE(stream->inVol);
-    SAFE_RELEASE(stream->outVol);
 
     CloseHandle(stream->event[S_INPUT]);
     CloseHandle(stream->event[S_OUTPUT]);