ContrastBase.cpp

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/**********************************************************************
 
  Audacity: A Digital Audio Editor
 
  ContrastBase.cpp
 
*//*******************************************************************/
#include "ContrastBase.h"
#include "BasicUI.h"
#include "Prefs.h"
#include "Project.h"
#include "ViewInfo.h"
#include "WaveChannelUtilities.h"
#include "WaveTrack.h"
 
bool ContrastBase::GetDB(float& dB)
{
   float rms = float(0.0);
 
   // For stereo tracks: sqrt((mean(L)+mean(R))/2)
   double meanSq = 0.0;
 
   auto& p = GetProject();
   auto range = TrackList::Get(p).Selected<const WaveTrack>();
   auto numberSelectedTracks = range.size();
   using namespace BasicUI;
   if (numberSelectedTracks > 1)
   {
      ShowMessageBox(
         XO("You can only measure one track at a time."),
         MessageBoxOptions {}.IconStyle(Icon::Error));
      return false;
   }
   if (numberSelectedTracks == 0)
   {
      ShowMessageBox(
         XO("Please select an audio track."),
         MessageBoxOptions {}.IconStyle(Icon::Error));
      return false;
   }
 
   const auto first = *range.begin();
   const auto channels = first->Channels();
   assert(mT0 <= mT1);
   // Ignore whitespace beyond ends of track.
   mT0 = std::max(mT0, first->GetStartTime());
   mT1 = std::min(mT1, first->GetEndTime());
   for (auto t : channels)
   {
 
      auto SelT0 = t->TimeToLongSamples(mT0);
      auto SelT1 = t->TimeToLongSamples(mT1);
 
      if (SelT0 > SelT1)
      {
         ShowMessageBox(
            XO("Invalid audio selection.\nPlease ensure that audio is selected."),
            MessageBoxOptions {}.IconStyle(Icon::Error));
         return false;
      }
 
      if (SelT0 == SelT1)
      {
         ShowMessageBox(
            XO("Nothing to measure.\nPlease select a section of a track."),
            MessageBoxOptions {}.IconStyle(Icon::Error));
         return false;
      }
 
      // Don't throw in this analysis dialog
      rms = WaveChannelUtilities::GetRMS(*t, mT0, mT1, false);
      meanSq += rms * rms;
   }
   // TODO: This works for stereo, provided the audio clips are in both
   // channels. We should really count gaps between clips as silence.
   rms = (meanSq > 0.0) ? sqrt(meanSq / static_cast<double>(channels.size())) :
                          0.0;
 
   // Gives warning C4056, Overflow in floating-point constant arithmetic
   // -INFINITY is intentional here.
   // Looks like we are stuck with this warning, as
   // #pragma warning( disable : 4056)
   // even around the whole function does not disable it successfully.
 
   dB = (rms == 0.0) ? -INFINITY : LINEAR_TO_DB(rms);
   return true;
}
 
void ContrastBase::SetStartAndEndTime()
{
   auto& p = GetProject();
   auto& selectedRegion = ViewInfo::Get(p).selectedRegion;
   mT0 = selectedRegion.t0();
   mT1 = selectedRegion.t1();
}