Mixer::WarpOptions constructor for common case

src/export/Export.cpp

@@ -59,7 +59,6 @@
 #include "../ProjectWindow.h"
 #include "../ShuttleGui.h"
 #include "../Tags.h"
-#include "../TimeTrack.h"
 #include "../WaveTrack.h"
 #include "../widgets/AudacityMessageBox.h"
 #include "../widgets/Warning.h"
@@ -234,13 +233,11 @@ std::unique_ptr<Mixer> ExportPlugin::CreateMixer(const TrackList &tracks,
    for (auto pTrack: range)
       inputTracks.push_back(
          pTrack->SharedPointer< const WaveTrack >() );
-   const auto timeTrack = *tracks.Any<const TimeTrack>().begin();
-   auto envelope = timeTrack ? timeTrack->GetEnvelope() : nullptr;
    // MB: the stop time should not be warped, this was a bug.
    return std::make_unique<Mixer>(inputTracks,
                   // Throw, to stop exporting, if read fails:
                   true,
-                  Mixer::WarpOptions(envelope),
+                  Mixer::WarpOptions{tracks},
                   startTime, stopTime,
                   numOutChannels, outBufferSize, outInterleaved,
                   outRate, outFormat,