An alpha-only toggle command for extra dropout detection; default off

src/AudioIO.cpp

@@ -5168,8 +5168,10 @@ int audacityAudioCallback(const void *inputBuffer, void *outputBuffer,
          bool inputError =
             (statusFlags & (paInputOverflow))
             && !(statusFlags & paPrimingOutput);
+
          // But it seems it's easy to get false positives, at least on Mac
-         wxUnusedVar( inputError );
+         // So we have not decided to enable this extra detection yet in
+         // production
 
          size_t len = framesPerBuffer;
          for(unsigned t = 0; t < numCaptureChannels; t++)
@@ -5186,7 +5188,7 @@ int audacityAudioCallback(const void *inputBuffer, void *outputBuffer,
          // enough from mCaptureBuffers; maybe it's CPU-bound, or maybe the
          // storage device it writes is too slow
          if (gAudioIO->mDetectDropouts &&
-             (//inputError ||
+             ((gAudioIO->mDetectUpstreamDropouts && inputError) ||
               len < framesPerBuffer) ) {
             // Assume that any good partial buffer should be written leftmost
             // and zeroes will be padded after; label the zeroes.

src/AudioIO.h

@@ -807,6 +807,10 @@ public:
 
    // Used only for testing purposes in alpha builds
    bool mSimulateRecordingErrors{ false };
+
+   // Whether to check the error code passed to audacityAudioCallback to
+   // detect more dropouts
+   bool mDetectUpstreamDropouts{ false };
 };
 
 #endif

src/Menus.cpp

@@ -1237,6 +1237,10 @@ void AudacityProject::CreateMenusAndCommands()
                   _("Simulate Recording Errors"),
                   FN(OnSimulateRecordingErrors),
                   gAudioIO->mSimulateRecordingErrors);
+      c->AddCheck(wxT("DetectUpstreamDropouts"),
+                  _("Detect Upstream Dropouts"),
+                  FN(OnDetectUpstreamDropouts),
+                  gAudioIO->mDetectUpstreamDropouts);
 #endif
 
       c->AddItem(wxT("Screenshot"), _("&Screenshot Tools..."), FN(OnScreenshot));
@@ -8422,6 +8426,13 @@ void AudacityProject::OnSimulateRecordingErrors(const CommandContext &)
    setting = !setting;
 }
 
+void AudacityProject::OnDetectUpstreamDropouts(const CommandContext &)
+{
+   bool &setting = gAudioIO->mDetectUpstreamDropouts;
+   mCommandManager.Check(wxT("DetectUpstreamDropouts"), !setting);
+   setting = !setting;
+}
+
 void AudacityProject::OnScreenshot(const CommandContext &)
 {
    ::OpenScreenshotTools();

src/Menus.h

@@ -510,6 +510,7 @@ void OnBenchmark(const CommandContext &);
 void OnCrashReport(const CommandContext &);
 #endif
 void OnSimulateRecordingErrors(const CommandContext &);
+void OnDetectUpstreamDropouts(const CommandContext &);
 void OnScreenshot(const CommandContext &);
 void OnAudioDeviceInfo(const CommandContext &);
 #ifdef EXPERIMENTAL_MIDI_OUT