Reimplement the insertion of zeroes at drop-outs...

... and correct for latency only when there is at least one playback track

src/AudioIO.cpp

@@ -2716,10 +2716,6 @@ void AudioIO::StopStream()
          double recordingOffset =
             mLastRecordingOffset + latencyCorrection / 1000.0;
 
-         for (auto &interval : mLostCaptureIntervals)
-            interval.first += recordingOffset,
-            interval.second += recordingOffset;
-
          for (unsigned int i = 0; i < mCaptureTracks.size(); i++) {
             // The calls to Flush, and (less likely) Clear and InsertSilence,
             // may cause exceptions because of exhaustion of disk space.
@@ -2791,6 +2787,19 @@ void AudioIO::StopStream()
                }
             } );
          }
+
+         for (auto &interval : mLostCaptureIntervals) {
+            auto &start = interval.first;
+            if (mPlaybackTracks.size() > 0)
+               // only do latency correction if some tracks are being played back
+               start += recordingOffset;
+            auto duration = interval.second;
+            for (auto &track : mCaptureTracks) {
+               GuardedCall([&] {
+                  track->SyncLockAdjust(start, start + duration);
+               });
+            }
+         }
       }
    }
 
@@ -5181,10 +5190,9 @@ int audacityAudioCallback(const void *inputBuffer, void *outputBuffer,
               len < framesPerBuffer) ) {
             // Assume that any good partial buffer should be written leftmost
             // and zeroes will be padded after; label the zeroes.
-            auto start = gAudioIO->mTime;
-            auto end = start + framesPerBuffer / gAudioIO->mRate;
-            auto middle = start + len / gAudioIO->mRate;
-            auto interval = std::make_pair( middle, end );
+            auto start = gAudioIO->mTime + len / gAudioIO->mRate;
+            auto duration = (framesPerBuffer - len) / gAudioIO->mRate;
+            auto interval = std::make_pair( start, duration );
             gAudioIO->mLostCaptureIntervals.push_back( interval );
          }
 
@@ -5239,20 +5247,6 @@ int audacityAudioCallback(const void *inputBuffer, void *outputBuffer,
                wxUnusedVar(put);
             }
          }
-
-         if (gAudioIO->mDetectDropouts &&
-             len < framesPerBuffer) {
-            for(unsigned t = 0; t < numCaptureChannels; t++) {
-               // Get here probably because of failure to keep up with real
-               // time, causing loss of input samples.
-               // Pad with zeroes
-               const auto put = gAudioIO->mCaptureBuffers[t]->Clear(
-                     gAudioIO->mCaptureFormat, framesPerBuffer - len);
-               // wxASSERT(put == len);
-               // but we can't assert in this thread
-               wxUnusedVar(put);
-            }
-         }
       }
 
       // Update the current time position if not scrubbing

src/AudioIO.h

@@ -801,6 +801,7 @@ private:
    bool mDetectDropouts{ true };
 
 public:
+   // Pairs of starting time and duration
    const std::vector< std::pair<double, double> > &LostCaptureIntervals()
    { return mLostCaptureIntervals; }
 

src/Project.cpp

@@ -5394,7 +5394,8 @@ void AudacityProject::OnAudioIOStopRecording()
          long counter = 1;
          for (auto &interval : intervals)
             pTrack->AddLabel(
-               SelectedRegion{ interval.first, interval.second },
+               SelectedRegion{ interval.first,
+                  interval.first + interval.second },
                wxString::Format(wxT("%ld"), counter++),
                -2 );
          ShowWarningDialog(this, wxT("DropoutDetected"), _("\