ExportMP3.cpp

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/**********************************************************************
 
  Audacity: A Digital Audio Editor
 
  ExportMP3.cpp
 
  Joshua Haberman
 
  This just acts as an interface to LAME. A Lame dynamic library must
  be present
 
  The difficulty in our approach is that we are attempting to use LAME
  in a way it was not designed to be used. LAME's API is reasonably
  consistent, so if we were linking directly against it we could expect
  this code to work with a variety of different LAME versions. However,
  the data structures change from version to version, and so linking
  with one version of the header and dynamically linking against a
  different version of the dynamic library will not work correctly.
 
  The solution is to find the lowest common denominator between versions.
  The bare minimum of functionality we must use is this:
      1. Initialize the library.
      2. Set, at minimum, the following global options:
          i.  input sample rate
          ii. input channels
      3. Encode the stream
      4. Call the finishing routine
 
  Just so that it's clear that we're NOT free to use whatever features
  of LAME we like, I'm not including lame.h, but instead enumerating
  here the extent of functions and structures that we can rely on being
  able to import and use from a dynamic library.
 
  For the record, we aim to support LAME 3.70 on. Since LAME 3.70 was
  released in April of 2000, that should be plenty.
 
 
  Copyright 2002, 2003 Joshua Haberman.
  Some portions may be Copyright 2003 Paolo Patruno.
 
  This program is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation; either version 2 of the License, or
  (at your option) any later version.
 
  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.
 
  You should have received a copy of the GNU General Public License
  along with this program; if not, write to the Free Software
  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 
*******************************************************************//********************************************************************/
 
 
#include "ExportMP3.h"
 
#include <wx/app.h>
#include <wx/defs.h>
 
#include <wx/choice.h>
#include <wx/checkbox.h>
#include <wx/dynlib.h>
#include <wx/ffile.h>
#include <wx/intl.h>
#include <wx/log.h>
#include <wx/mimetype.h>
#include <wx/radiobut.h>
#include <wx/stattext.h>
#include <wx/textctrl.h>
#include <wx/timer.h>
#include <wx/utils.h>
#include <wx/window.h>
 
#include "FileNames.h"
#include "float_cast.h"
#include "../Mix.h"
#include "Prefs.h"
#include "ProjectRate.h"
#include "../ProjectSettings.h"
#include "../ProjectWindow.h"
#include "../SelectFile.h"
#include "../ShuttleGui.h"
#include "../Tags.h"
#include "../Track.h"
#include "../widgets/HelpSystem.h"
#include "../widgets/AudacityMessageBox.h"
#include "../widgets/ProgressDialog.h"
#include "wxFileNameWrapper.h"
 
#include "Export.h"
 
#include <lame/lame.h>
 
#ifdef USE_LIBID3TAG
#include <id3tag.h>
#endif
 
//----------------------------------------------------------------------------
// ExportMP3Options
//----------------------------------------------------------------------------
 
enum MP3ChannelMode : unsigned {
   CHANNEL_JOINT = 0,
   CHANNEL_STEREO = 1,
   CHANNEL_MONO = 2,
};
 
enum : int {
   QUALITY_2 = 2,
 
   //ROUTINE_FAST = 0,
   //ROUTINE_STANDARD = 1,
 
   PRESET_INSANE = 0,
   PRESET_EXTREME = 1,
   PRESET_STANDARD = 2,
   PRESET_MEDIUM = 3,
};
 
/* i18n-hint: kbps is the bitrate of the MP3 file, kilobits per second*/
inline TranslatableString n_kbps( int n ){ return XO("%d kbps").Format( n ); }
 
static const TranslatableStrings fixRateNames {
   n_kbps(320),
   n_kbps(256),
   n_kbps(224),
   n_kbps(192),
   n_kbps(160),
   n_kbps(144),
   n_kbps(128),
   n_kbps(112),
   n_kbps(96),
   n_kbps(80),
   n_kbps(64),
   n_kbps(56),
   n_kbps(48),
   n_kbps(40),
   n_kbps(32),
   n_kbps(24),
   n_kbps(16),
   n_kbps(8),
};
 
static const std::vector<int> fixRateValues {
   320,
   256,
   224,
   192,
   160,
   144,
   128,
   112,
   96,
   80,
   64,
   56,
   48,
   40,
   32,
   24,
   16,
   8,
};
 
static const TranslatableStrings varRateNames {
   XO("220-260 kbps (Best Quality)"),
   XO("200-250 kbps"),
   XO("170-210 kbps"),
   XO("155-195 kbps"),
   XO("145-185 kbps"),
   XO("110-150 kbps"),
   XO("95-135 kbps"),
   XO("80-120 kbps"),
   XO("65-105 kbps"),
   XO("45-85 kbps (Smaller files)"),
};
/*
static const TranslatableStrings varModeNames {
   XO("Fast"),
   XO("Standard"),
};
*/
static const TranslatableStrings setRateNames {
   /* i18n-hint: Slightly humorous - as in use an insane precision with MP3.*/
   XO("Insane, 320 kbps"),
   XO("Extreme, 220-260 kbps"),
   XO("Standard, 170-210 kbps"),
   XO("Medium, 145-185 kbps"),
};
 
static const TranslatableStrings setRateNamesShort {
   /* i18n-hint: Slightly humorous - as in use an insane precision with MP3.*/
   XO("Insane"),
   XO("Extreme"),
   XO("Standard"),
   XO("Medium"),
};
 
static const std::vector< int > sampRates {
   8000,
   11025,
   12000,
   16000,
   22050,
   24000,
   32000,
   44100,
   48000,
};
 
#define ID_SET 7000
#define ID_VBR 7001
#define ID_ABR 7002
#define ID_CBR 7003
#define ID_QUALITY 7004
#define ID_MONO 7005
 
class ExportMP3Options final : public wxPanelWrapper
{
public:
 
   ExportMP3Options(wxWindow *parent, int format);
   virtual ~ExportMP3Options();
 
   void PopulateOrExchange(ShuttleGui & S);
   bool TransferDataToWindow() override;
   bool TransferDataFromWindow() override;
 
   void OnSET(wxCommandEvent& evt);
   void OnVBR(wxCommandEvent& evt);
   void OnABR(wxCommandEvent& evt);
   void OnCBR(wxCommandEvent& evt);
   void OnQuality(wxCommandEvent& evt);
   void OnMono(wxCommandEvent& evt);
 
   void LoadNames(const TranslatableStrings &choices);
 
private:
 
   wxRadioButton *mStereo;
   wxRadioButton *mJoint;
   wxCheckBox    *mMono;
   wxRadioButton *mSET;
   wxRadioButton *mVBR;
   wxRadioButton *mABR;
   wxRadioButton *mCBR;
   wxChoice *mRate;
   //wxChoice *mMode;
 
   long mSetRate;
   long mVbrRate;
   long mAbrRate;
   long mCbrRate;
 
   DECLARE_EVENT_TABLE()
};
 
BEGIN_EVENT_TABLE(ExportMP3Options, wxPanelWrapper)
   EVT_RADIOBUTTON(ID_SET,    ExportMP3Options::OnSET)
   EVT_RADIOBUTTON(ID_VBR,    ExportMP3Options::OnVBR)
   EVT_RADIOBUTTON(ID_ABR,    ExportMP3Options::OnABR)
   EVT_RADIOBUTTON(ID_CBR,    ExportMP3Options::OnCBR)
   EVT_CHOICE(wxID_ANY,       ExportMP3Options::OnQuality)
   EVT_CHECKBOX(ID_MONO,      ExportMP3Options::OnMono)
END_EVENT_TABLE()
 
ExportMP3Options::ExportMP3Options(wxWindow *parent, int WXUNUSED(format))
:  wxPanelWrapper(parent, wxID_ANY)
{
   mSetRate = gPrefs->Read(wxT("/FileFormats/MP3SetRate"), PRESET_STANDARD);
   mVbrRate = gPrefs->Read(wxT("/FileFormats/MP3VbrRate"), QUALITY_2);
   mAbrRate = gPrefs->Read(wxT("/FileFormats/MP3AbrRate"), 192);
   mCbrRate = gPrefs->Read(wxT("/FileFormats/MP3CbrRate"), 192);
 
   ShuttleGui S(this, eIsCreatingFromPrefs);
   PopulateOrExchange(S);
 
   TransferDataToWindow();
}
 
ExportMP3Options::~ExportMP3Options()
{
   TransferDataFromWindow();
}
 
EnumSetting< MP3RateMode > MP3RateModeSetting{
   wxT("/FileFormats/MP3RateModeChoice"),
   {
      { wxT("SET"), XXO("Preset") },
      { wxT("VBR"), XXO("Variable") },
      { wxT("ABR"), XXO("Average") },
      { wxT("CBR"), XXO("Constant") },
   },
   0, // MODE_SET
 
   // for migrating old preferences:
   {
      MODE_SET, MODE_VBR, MODE_ABR, MODE_CBR
   },
   wxT("/FileFormats/MP3RateMode"),
};
 
static EnumSetting< MP3ChannelMode > MP3ChannelModeSetting{
   wxT("/FileFormats/MP3ChannelModeChoice"),
   {
      EnumValueSymbol{ wxT("JOINT"), XXO("Joint Stereo") },
      EnumValueSymbol{ wxT("STEREO"), XXO("Stereo") },
   },
   0, // CHANNEL_JOINT
 
   // for migrating old preferences:
   {
      CHANNEL_JOINT, CHANNEL_STEREO,
   },
   wxT("/FileFormats/MP3ChannelMode"),
};
 
void ExportMP3Options::PopulateOrExchange(ShuttleGui & S)
{
   bool mono = false;
   gPrefs->Read(wxT("/FileFormats/MP3ForceMono"), &mono, 0);
 
   const TranslatableStrings *choices = nullptr;
   const std::vector< int > *codes = nullptr;
   //bool enable;
   int defrate;
 
   S.StartVerticalLay();
   {
      S.StartHorizontalLay(wxCENTER);
      {
         S.StartMultiColumn(2, wxCENTER);
         {
            S.SetStretchyCol(1);
            S.StartTwoColumn();
            {
               S.AddPrompt(XXO("Bit Rate Mode:"));
 
               // Bug 2692: Place button group in panel so tabbing will work and,
               // on the Mac, VoiceOver will announce as radio buttons.
               S.StartPanel();
               {
                  S.StartHorizontalLay();
                  {
                     S.StartRadioButtonGroup(MP3RateModeSetting);
                     {
                        mSET = S.Id(ID_SET).TieRadioButton();
                        mVBR = S.Id(ID_VBR).TieRadioButton();
                        mABR = S.Id(ID_ABR).TieRadioButton();
                        mCBR = S.Id(ID_CBR).TieRadioButton();
                     }
                     S.EndRadioButtonGroup();
                  }
                  S.EndHorizontalLay();
               }
               S.EndPanel();
 
               /* PRL: unfortunately this bit of procedural code must
                interrupt the mostly-declarative dialog description, until
                we find a better solution.  Because when shuttling values
                from the dialog, we must shuttle out the MP3RateModeSetting
                first. */
 
               switch( MP3RateModeSetting.ReadEnum() ) {
                  case MODE_SET:
                     choices = &setRateNames;
                     //enable = true;
                     defrate = mSetRate;
                     break;
 
                  case MODE_VBR:
                     choices = &varRateNames;
                     //enable = true;
                     defrate = mVbrRate;
                     break;
 
                  case MODE_ABR:
                     choices = &fixRateNames;
                     codes = &fixRateValues;
                     //enable = false;
                     defrate = mAbrRate;
                     break;
 
                  case MODE_CBR:
                  default:
                     choices = &fixRateNames;
                     codes = &fixRateValues;
                     //enable = false;
                     defrate = mCbrRate;
                     break;
               }
 
               mRate = S.Id(ID_QUALITY).TieNumberAsChoice(
                  XXO("Quality"),
                  { wxT("/FileFormats/MP3Bitrate"), defrate },
                  *choices,
                  codes
               );
               /*
               mMode = S.Disable(!enable)
                  .TieNumberAsChoice(
                     XXO("Variable Speed:"),
                     { wxT("/FileFormats/MP3VarMode"), ROUTINE_FAST },
                     varModeNames );
               */
               S.AddPrompt(XXO("Channel Mode:"));
               S.StartMultiColumn(2, wxEXPAND);
               {
                  // Bug 2692: Place button group in panel so tabbing will work and,
                  // on the Mac, VoiceOver will announce as radio buttons.
                  S.StartPanel();
                  {
                     S.StartHorizontalLay();
                     {
                        S.StartRadioButtonGroup(MP3ChannelModeSetting);
                        {
                           mJoint = S.Disable(mono)
                              .TieRadioButton();
                           mStereo = S.Disable(mono)
                              .TieRadioButton();
                        }
                        S.EndRadioButtonGroup();
                     }
                     S.EndHorizontalLay();
                  }
                  S.EndPanel();
 
                  mMono = S.Id(ID_MONO).AddCheckBox(XXO("Force export to mono"), mono);
               }
               S.EndMultiColumn();
            }
            S.EndTwoColumn();
         }
         S.EndMultiColumn();
      }
      S.EndHorizontalLay();
   }
   S.EndVerticalLay();
}
 
bool ExportMP3Options::TransferDataToWindow()
{
   return true;
}
 
bool ExportMP3Options::TransferDataFromWindow()
{
   ShuttleGui S(this, eIsSavingToPrefs);
   PopulateOrExchange(S);
 
   gPrefs->Write(wxT("/FileFormats/MP3SetRate"), mSetRate);
   gPrefs->Write(wxT("/FileFormats/MP3VbrRate"), mVbrRate);
   gPrefs->Write(wxT("/FileFormats/MP3AbrRate"), mAbrRate);
   gPrefs->Write(wxT("/FileFormats/MP3CbrRate"), mCbrRate);
   gPrefs->Flush();
 
   return true;
}
 
namespace {
 
int ValidateValue( int nValues, int value, int defaultValue )
{
   return (value >= 0 && value < nValues) ? value : defaultValue;
}
 
int ValidateValue( const std::vector<int> &values, int value, int defaultValue )
{
   auto start = values.begin(), finish = values.end(),
      iter = std::find( start, finish, value );
   return ( iter != finish ) ? value : defaultValue;
}
 
int ValidateIndex( const std::vector<int> &values, int value, int defaultIndex )
{
   auto start = values.begin(), finish = values.end(),
      iter = std::find( start, finish, value );
   return ( iter != finish ) ? static_cast<int>( iter - start ) : defaultIndex;
}
 
}
 
void ExportMP3Options::OnSET(wxCommandEvent& WXUNUSED(event))
{
   LoadNames(setRateNames);
 
   mRate->SetSelection(ValidateValue(setRateNames.size(), mSetRate, 2));
   mRate->Refresh();
   //mMode->Enable(true);
}
 
void ExportMP3Options::OnVBR(wxCommandEvent& WXUNUSED(event))
{
   LoadNames(varRateNames);
 
   mRate->SetSelection(ValidateValue(varRateNames.size(), mVbrRate, 2));
   mRate->Refresh();
   //mMode->Enable(true);
}
 
void ExportMP3Options::OnABR(wxCommandEvent& WXUNUSED(event))
{
   LoadNames(fixRateNames);
 
   mRate->SetSelection(ValidateIndex(fixRateValues, mAbrRate, 10));
   mRate->Refresh();
   //mMode->Enable(false);
}
 
void ExportMP3Options::OnCBR(wxCommandEvent& WXUNUSED(event))
{
   LoadNames(fixRateNames);
 
   mRate->SetSelection(ValidateIndex(fixRateValues, mCbrRate, 10));
   mRate->Refresh();
   //mMode->Enable(false);
}
 
void ExportMP3Options::OnQuality(wxCommandEvent& WXUNUSED(event))
{
   int sel = mRate->GetSelection();
 
   if (mSET->GetValue()) {
      mSetRate = sel;
   }
   else if (mVBR->GetValue()) {
      mVbrRate = sel;
   }
   else if (mABR->GetValue()) {
      mAbrRate = fixRateValues[ sel ];
   }
   else {
      mCbrRate = fixRateValues[ sel ];
   }
}
 
void ExportMP3Options::OnMono(wxCommandEvent& /*evt*/)
{
   bool mono = false;
   mono = mMono->GetValue();
   mJoint->Enable(!mono);
   mStereo->Enable(!mono);
 
   gPrefs->Write(wxT("/FileFormats/MP3ForceMono"), mono);
   gPrefs->Flush();
}
 
void ExportMP3Options::LoadNames(const TranslatableStrings &names)
{
   mRate->Clear();
   for (const auto &name : names)
      mRate->Append( name.Translation() );
}
 
//----------------------------------------------------------------------------
// FindDialog
//----------------------------------------------------------------------------
 
#define ID_BROWSE 5000
#define ID_DLOAD  5001
 
class FindDialog final : public wxDialogWrapper
{
public:
 
#ifndef DISABLE_DYNAMIC_LOADING_LAME
 
   FindDialog(wxWindow *parent, wxString path, wxString name,
      FileNames::FileTypes types)
   :  wxDialogWrapper(parent, wxID_ANY,
   /* i18n-hint: LAME is the name of an MP3 converter and should not be translated*/
   XO("Locate LAME"))
   {
      SetName();
      ShuttleGui S(this, eIsCreating);
 
      mPath = path;
      mName = name;
      mTypes = std::move( types );
 
      mLibPath.Assign(mPath, mName);
 
      PopulateOrExchange(S);
   }
 
   void PopulateOrExchange(ShuttleGui & S)
   {
      S.SetBorder(10);
      S.StartVerticalLay(true);
      {
         S.AddTitle(
            XO("Audacity needs the file %s to create MP3s.")
               .Format( mName ) );
 
         S.SetBorder(3);
         S.StartHorizontalLay(wxALIGN_LEFT, true);
         {
            S.AddTitle( XO("Location of %s:").Format( mName ) );
         }
         S.EndHorizontalLay();
 
         S.StartMultiColumn(2, wxEXPAND);
         S.SetStretchyCol(0);
         {
            if (mLibPath.GetFullPath().empty()) {
               mPathText = S.AddTextBox( {},
                  /* i18n-hint: There is a  button to the right of the arrow.*/
                  wxString::Format(_("To find %s, click here -->"), mName), 0);
            }
            else {
               mPathText = S.AddTextBox( {}, mLibPath.GetFullPath(), 0);
            }
            S.Id(ID_BROWSE).AddButton(XXO("Browse..."), wxALIGN_RIGHT);
            S.AddVariableText(
               /* i18n-hint: There is a  button to the right of the arrow.*/
               XO("To get a free copy of LAME, click here -->"), true);
            /* i18n-hint: (verb)*/
            S.Id(ID_DLOAD).AddButton(XXO("Download"), wxALIGN_RIGHT);
         }
         S.EndMultiColumn();
 
         S.AddStandardButtons();
      }
      S.EndVerticalLay();
 
      Layout();
      Fit();
      SetMinSize(GetSize());
      Center();
 
      return;
   }
 
   void OnBrowse(wxCommandEvent & WXUNUSED(event))
   {
      /* i18n-hint: It's asking for the location of a file, for
       * example, "Where is lame_enc.dll?" - you could translate
       * "Where would I find the file %s" instead if you want. */
      auto question = XO("Where is %s?").Format( mName );
 
      wxString path = SelectFile(FileNames::Operation::_None,
         question,
            mLibPath.GetPath(),
            mLibPath.GetName(),
            wxT(""),
            mTypes,
            wxFD_OPEN | wxRESIZE_BORDER,
            this);
      if (!path.empty()) {
         mLibPath = path;
         mPathText->SetValue(path);
      }
   }
 
   void OnDownload(wxCommandEvent & WXUNUSED(event))
   {
      HelpSystem::ShowHelp(this, L"FAQ:Installing_the_LAME_MP3_Encoder");
   }
 
   wxString GetLibPath()
   {
      return mLibPath.GetFullPath();
   }
 
#endif // DISABLE_DYNAMIC_LOADING_LAME
 
private:
 
#ifndef DISABLE_DYNAMIC_LOADING_LAME
   wxFileName mLibPath;
 
   wxString mPath;
   wxString mName;
   FileNames::FileTypes mTypes;
#endif // DISABLE_DYNAMIC_LOADING_LAME
 
   wxTextCtrl *mPathText;
 
   DECLARE_EVENT_TABLE()
};
 
#ifndef DISABLE_DYNAMIC_LOADING_LAME
BEGIN_EVENT_TABLE(FindDialog, wxDialogWrapper)
   EVT_BUTTON(ID_BROWSE, FindDialog::OnBrowse)
   EVT_BUTTON(ID_DLOAD,  FindDialog::OnDownload)
END_EVENT_TABLE()
#endif // DISABLE_DYNAMIC_LOADING_LAME
 
//----------------------------------------------------------------------------
// MP3Exporter
//----------------------------------------------------------------------------
 
#ifndef DISABLE_DYNAMIC_LOADING_LAME
 
typedef lame_global_flags *lame_init_t(void);
typedef int lame_init_params_t(lame_global_flags*);
typedef const char* get_lame_version_t(void);
 
typedef int CDECL lame_encode_buffer_ieee_float_t(
      lame_t          gfp,
      const float     pcm_l[],
      const float     pcm_r[],
      const int       nsamples,
      unsigned char * mp3buf,
      const int       mp3buf_size);
 
typedef int CDECL lame_encode_buffer_interleaved_ieee_float_t(
      lame_t          gfp,
      const float     pcm[],
      const int       nsamples,
      unsigned char * mp3buf,
      const int       mp3buf_size);
 
typedef int lame_encode_flush_t(
      lame_global_flags *gf,
      unsigned char*     mp3buf,
      int                size );
 
typedef int lame_close_t(lame_global_flags*);
 
typedef int lame_set_in_samplerate_t(lame_global_flags*, int);
typedef int lame_set_out_samplerate_t(lame_global_flags*, int);
typedef int lame_set_num_channels_t(lame_global_flags*, int );
typedef int lame_set_quality_t(lame_global_flags*, int);
typedef int lame_set_brate_t(lame_global_flags*, int);
typedef int lame_set_VBR_t(lame_global_flags *, vbr_mode);
typedef int lame_set_VBR_q_t(lame_global_flags *, int);
typedef int lame_set_VBR_min_bitrate_kbps_t(lame_global_flags *, int);
typedef int lame_set_mode_t(lame_global_flags *, MPEG_mode);
typedef int lame_set_preset_t(lame_global_flags *, int);
typedef int lame_set_error_protection_t(lame_global_flags *, int);
typedef int lame_set_disable_reservoir_t(lame_global_flags *, int);
typedef int lame_set_bWriteVbrTag_t(lame_global_flags *, int);
typedef size_t lame_get_lametag_frame_t(const lame_global_flags *, unsigned char* buffer, size_t size);
typedef void lame_mp3_tags_fid_t(lame_global_flags *, FILE *);
 
#endif // DISABLE_DYNAMIC_LOADING_LAME
 
#if defined(__WXMSW__)
// An alternative solution to give Windows an additional chance of writing the tag before
// falling bato to lame_mp3_tag_fid().  The latter can have DLL sharing issues when mixing
// Debug/Release builds of Audacity and the lame DLL.
typedef unsigned long beWriteInfoTag_t(lame_global_flags *, char *);
 
// We use this to determine if the user has selected an older, Blade API only, lame_enc.dll
// so we can be more specific about why their library isn't acceptable.
typedef struct {
 
   // BladeEnc DLL Version number
 
   BYTE  byDLLMajorVersion;
   BYTE  byDLLMinorVersion;
 
   // BladeEnc Engine Version Number
 
   BYTE  byMajorVersion;
   BYTE  byMinorVersion;
 
   // DLL Release date
 
   BYTE  byDay;
   BYTE  byMonth;
   WORD  wYear;
 
   // BladeEnc Homepage URL
 
   CHAR  zHomepage[129];
 
   BYTE  byAlphaLevel;
   BYTE  byBetaLevel;
   BYTE  byMMXEnabled;
 
   BYTE  btReserved[125];
} be_version;
typedef void beVersion_t(be_version *);
#endif
 
class MP3Exporter
{
public:
   enum AskUser
   {
      No,
      Maybe,
      Yes
   };
 
   MP3Exporter();
   ~MP3Exporter();
 
#ifndef DISABLE_DYNAMIC_LOADING_LAME
   bool FindLibrary(wxWindow *parent);
   bool LoadLibrary(wxWindow *parent, AskUser askuser);
   bool ValidLibraryLoaded();
#endif // DISABLE_DYNAMIC_LOADING_LAME
 
   /* These global settings keep state over the life of the object */
   void SetMode(int mode);
   void SetBitrate(int rate);
   void SetQuality(int q/*, int r*/);
   void SetChannel(int mode);
 
   /* Virtual methods that must be supplied by library interfaces */
 
   /* initialize the library interface */
   bool InitLibrary(wxString libpath);
   bool InitLibraryInternal();
   bool InitLibraryExternal(wxString libpath);
   void FreeLibrary();
 
   /* get library info */
   wxString GetLibraryVersion();
   wxString GetLibraryName();
   wxString GetLibraryPath();
   FileNames::FileTypes GetLibraryTypes();
 
   /* returns the number of samples PER CHANNEL to send for each call to EncodeBuffer */
   int InitializeStream(unsigned channels, int sampleRate);
 
   /* In bytes. must be called AFTER InitializeStream */
   int GetOutBufferSize();
 
   /* returns the number of bytes written. input is interleaved if stereo*/
   int EncodeBuffer(float inbuffer[], unsigned char outbuffer[]);
   int EncodeRemainder(float inbuffer[], int nSamples,
                       unsigned char outbuffer[]);
 
   int EncodeBufferMono(float inbuffer[], unsigned char outbuffer[]);
   int EncodeRemainderMono(float inbuffer[], int nSamples,
                           unsigned char outbuffer[]);
 
   int FinishStream(unsigned char outbuffer[]);
   void CancelEncoding();
 
   bool PutInfoTag(wxFFile & f, wxFileOffset off);
 
private:
   bool mLibIsExternal;
 
#ifndef DISABLE_DYNAMIC_LOADING_LAME
   wxString mLibPath;
   wxDynamicLibrary lame_lib;
   bool mLibraryLoaded;
#endif // DISABLE_DYNAMIC_LOADING_LAME
 
#if defined(__WXMSW__)
   TranslatableString mBladeVersion;
#endif
 
   bool mEncoding;
   int mMode;
   int mBitrate;
   int mQuality;
   //int mRoutine;
   int mChannel;
 
#ifndef DISABLE_DYNAMIC_LOADING_LAME
   /* function pointers to the symbols we get from the library */
   lame_init_t* lame_init;
   lame_init_params_t* lame_init_params;
   lame_encode_buffer_ieee_float_t* lame_encode_buffer_ieee_float;
   lame_encode_buffer_interleaved_ieee_float_t* lame_encode_buffer_interleaved_ieee_float;
   lame_encode_flush_t* lame_encode_flush;
   lame_close_t* lame_close;
   get_lame_version_t* get_lame_version;
 
   lame_set_in_samplerate_t* lame_set_in_samplerate;
   lame_set_out_samplerate_t* lame_set_out_samplerate;
   lame_set_num_channels_t* lame_set_num_channels;
   lame_set_quality_t* lame_set_quality;
   lame_set_brate_t* lame_set_brate;
   lame_set_VBR_t* lame_set_VBR;
   lame_set_VBR_q_t* lame_set_VBR_q;
   lame_set_VBR_min_bitrate_kbps_t* lame_set_VBR_min_bitrate_kbps;
   lame_set_mode_t* lame_set_mode;
   lame_set_preset_t* lame_set_preset;
   lame_set_error_protection_t* lame_set_error_protection;
   lame_set_disable_reservoir_t *lame_set_disable_reservoir;
   lame_set_bWriteVbrTag_t *lame_set_bWriteVbrTag;
   lame_get_lametag_frame_t *lame_get_lametag_frame;
   lame_mp3_tags_fid_t *lame_mp3_tags_fid;
#if defined(__WXMSW__)
   beWriteInfoTag_t *beWriteInfoTag;
   beVersion_t *beVersion;
#endif
#endif // DISABLE_DYNAMIC_LOADING_LAME
 
   lame_global_flags *mGF;
 
   static const int mSamplesPerChunk = 220500;
   // See lame.h/lame_encode_buffer() for further explanation
   // As coded here, this should be the worst case.
   static const int mOutBufferSize =
      mSamplesPerChunk * (320 / 8) / 8 + 4 * 1152 * (320 / 8) / 8 + 512;
 
   // See MAXFRAMESIZE in libmp3lame/VbrTag.c for explanation of 2880.
   unsigned char mInfoTagBuf[2880];
   size_t mInfoTagLen;
};
 
MP3Exporter::MP3Exporter()
{
// We could use #defines rather than this variable.
// The idea of the variable is that if we wanted, we could allow
// a dynamic override of the library, e.g. with a newer faster version,
// or to fix CVEs in the underlying librray.
// for now though the 'variable' is a constant.
#ifdef MP3_EXPORT_BUILT_IN
   mLibIsExternal = false;
#else
   mLibIsExternal = true;
#endif
 
#ifndef DISABLE_DYNAMIC_LOADING_LAME
   mLibraryLoaded = false;
#endif // DISABLE_DYNAMIC_LOADING_LAME
   mEncoding = false;
   mGF = NULL;
 
#ifndef DISABLE_DYNAMIC_LOADING_LAME
   if (gPrefs) {
      mLibPath = gPrefs->Read(wxT("/MP3/MP3LibPath"), wxT(""));
   }
#endif // DISABLE_DYNAMIC_LOADING_LAME
 
   mBitrate = 128;
   mQuality = QUALITY_2;
   mChannel = CHANNEL_STEREO;
   mMode = MODE_CBR;
   //mRoutine = ROUTINE_FAST;
}
 
MP3Exporter::~MP3Exporter()
{
   FreeLibrary();
}
 
#ifndef DISABLE_DYNAMIC_LOADING_LAME
 
bool MP3Exporter::FindLibrary(wxWindow *parent)
{
   wxString path;
   wxString name;
 
   if (!mLibPath.empty()) {
      wxFileName fn = mLibPath;
      path = fn.GetPath();
      name = fn.GetFullName();
   }
   else {
      path = GetLibraryPath();
      name = GetLibraryName();
   }
 
   FindDialog fd(parent,
      path,
      name,
      GetLibraryTypes());
 
   if (fd.ShowModal() == wxID_CANCEL) {
      return false;
   }
 
   path = fd.GetLibPath();
 
   if (!::wxFileExists(path)) {
      return false;
   }
 
   mLibPath = path;
 
   return (gPrefs->Write(wxT("/MP3/MP3LibPath"), mLibPath) && gPrefs->Flush());
}
 
bool MP3Exporter::LoadLibrary(wxWindow *parent, AskUser askuser)
{
 
   if (ValidLibraryLoaded()) {
      FreeLibrary();
      mLibraryLoaded = false;
   }
 
#if defined(__WXMSW__)
   mBladeVersion = {};
#endif
 
   if( !mLibIsExternal ){
      mLibraryLoaded = InitLibraryInternal();
      return mLibraryLoaded;
   }
 
   // First try loading it from a previously located path
   if (!mLibPath.empty()) {
      wxLogMessage(wxT("Attempting to load LAME from previously defined path"));
      mLibraryLoaded = InitLibrary(mLibPath);
   }
 
   // If not successful, try loading using system search paths
   if (!ValidLibraryLoaded()) {
      wxLogMessage(wxT("Attempting to load LAME from system search paths"));
      mLibPath = GetLibraryName();
      mLibraryLoaded = InitLibrary(mLibPath);
   }
 
   // If not successful, try loading using compiled in path
   if (!ValidLibraryLoaded()) {
      wxLogMessage(wxT("Attempting to load LAME from builtin path"));
      wxFileName fn(GetLibraryPath(), GetLibraryName());
      mLibPath = fn.GetFullPath();
      mLibraryLoaded = InitLibrary(mLibPath);
   }
 
   // If not successful, must ask the user
   if (!ValidLibraryLoaded()) {
      wxLogMessage(wxT("(Maybe) ask user for library"));
      if (askuser == MP3Exporter::Maybe && FindLibrary(parent)) {
         mLibraryLoaded = InitLibrary(mLibPath);
      }
   }
 
   // Oh well, just give up
   if (!ValidLibraryLoaded()) {
#if defined(__WXMSW__)
      if (askuser && !mBladeVersion.empty()) {
         AudacityMessageBox( mBladeVersion );
      }
#endif
      wxLogMessage(wxT("Failed to locate LAME library"));
 
      return false;
   }
 
   wxLogMessage(wxT("LAME library successfully loaded"));
 
   return true;
}
 
bool MP3Exporter::ValidLibraryLoaded()
{
   return mLibraryLoaded;
}
 
#endif // DISABLE_DYNAMIC_LOADING_LAME
 
void MP3Exporter::SetMode(int mode)
{
   mMode = mode;
}
 
void MP3Exporter::SetBitrate(int rate)
{
   mBitrate = rate;
}
 
void MP3Exporter::SetQuality(int q/*, int r*/)
{
   mQuality = q;
   //mRoutine = r;
}
 
void MP3Exporter::SetChannel(int mode)
{
   mChannel = mode;
}
 
bool MP3Exporter::InitLibrary(wxString libpath)
{
   return mLibIsExternal ? InitLibraryExternal(libpath) : InitLibraryInternal();
}
 
bool MP3Exporter::InitLibraryInternal()
{
   wxLogMessage(wxT("Using internal LAME"));
 
// The global ::lame_something symbols only exist if LAME is built in.
// So we don't reference them unless they are.
#ifdef MP3_EXPORT_BUILT_IN 
 
   lame_init = ::lame_init;
   get_lame_version = ::get_lame_version;
   lame_init_params = ::lame_init_params;
   lame_encode_buffer_ieee_float = ::lame_encode_buffer_ieee_float;
   lame_encode_buffer_interleaved_ieee_float = ::lame_encode_buffer_interleaved_ieee_float;
   lame_encode_flush = ::lame_encode_flush;
   lame_close = ::lame_close;
 
   lame_set_in_samplerate = ::lame_set_in_samplerate;
   lame_set_out_samplerate = ::lame_set_out_samplerate;
   lame_set_num_channels = ::lame_set_num_channels;
   lame_set_quality = ::lame_set_quality;
   lame_set_brate = ::lame_set_brate;
   lame_set_VBR = ::lame_set_VBR;
   lame_set_VBR_q = ::lame_set_VBR_q;
   lame_set_VBR_min_bitrate_kbps = ::lame_set_VBR_min_bitrate_kbps;
   lame_set_mode = ::lame_set_mode;
   lame_set_preset = ::lame_set_preset;
   lame_set_error_protection = ::lame_set_error_protection;
   lame_set_disable_reservoir = ::lame_set_disable_reservoir;
   lame_set_bWriteVbrTag = ::lame_set_bWriteVbrTag;
 
   // These are optional
   //lame_get_lametag_frame = ::lame_get_lametag_frame;
   lame_get_lametag_frame = NULL;
   lame_mp3_tags_fid = ::lame_mp3_tags_fid;
 
#if defined(__WXMSW__)
   //beWriteInfoTag = ::beWriteInfoTag;
   //beVersion = ::beVersion;
   beWriteInfoTag = NULL;
   beVersion = NULL;
#endif
 
   mGF = lame_init();
   if (mGF == NULL) {
      return false;
   }
#endif
 
   return true;
}
 
 
bool MP3Exporter::InitLibraryExternal(wxString libpath)
{
   wxLogMessage(wxT("Loading LAME from %s"), libpath);
 
#ifndef DISABLE_DYNAMIC_LOADING_LAME
   if (!lame_lib.Load(libpath, wxDL_LAZY)) {
      wxLogMessage(wxT("load failed"));
      return false;
   }
 
   wxLogMessage(wxT("Actual LAME path %s"),
              FileNames::PathFromAddr(lame_lib.GetSymbol(wxT("lame_init"))));
 
   lame_init = (lame_init_t *)
      lame_lib.GetSymbol(wxT("lame_init"));
   get_lame_version = (get_lame_version_t *)
      lame_lib.GetSymbol(wxT("get_lame_version"));
   lame_init_params = (lame_init_params_t *)
      lame_lib.GetSymbol(wxT("lame_init_params"));
   lame_encode_buffer_ieee_float = (lame_encode_buffer_ieee_float_t *)
      lame_lib.GetSymbol(wxT("lame_encode_buffer_ieee_float"));
   lame_encode_buffer_interleaved_ieee_float = (lame_encode_buffer_interleaved_ieee_float_t *)
      lame_lib.GetSymbol(wxT("lame_encode_buffer_interleaved_ieee_float"));
   lame_encode_flush = (lame_encode_flush_t *)
      lame_lib.GetSymbol(wxT("lame_encode_flush"));
   lame_close = (lame_close_t *)
      lame_lib.GetSymbol(wxT("lame_close"));
 
   lame_set_in_samplerate = (lame_set_in_samplerate_t *)
       lame_lib.GetSymbol(wxT("lame_set_in_samplerate"));
   lame_set_out_samplerate = (lame_set_out_samplerate_t *)
       lame_lib.GetSymbol(wxT("lame_set_out_samplerate"));
   lame_set_num_channels = (lame_set_num_channels_t *)
       lame_lib.GetSymbol(wxT("lame_set_num_channels"));
   lame_set_quality = (lame_set_quality_t *)
       lame_lib.GetSymbol(wxT("lame_set_quality"));
   lame_set_brate = (lame_set_brate_t *)
       lame_lib.GetSymbol(wxT("lame_set_brate"));
   lame_set_VBR = (lame_set_VBR_t *)
       lame_lib.GetSymbol(wxT("lame_set_VBR"));
   lame_set_VBR_q = (lame_set_VBR_q_t *)
       lame_lib.GetSymbol(wxT("lame_set_VBR_q"));
   lame_set_VBR_min_bitrate_kbps = (lame_set_VBR_min_bitrate_kbps_t *)
       lame_lib.GetSymbol(wxT("lame_set_VBR_min_bitrate_kbps"));
   lame_set_mode = (lame_set_mode_t *)
       lame_lib.GetSymbol(wxT("lame_set_mode"));
   lame_set_preset = (lame_set_preset_t *)
       lame_lib.GetSymbol(wxT("lame_set_preset"));
   lame_set_error_protection = (lame_set_error_protection_t *)
       lame_lib.GetSymbol(wxT("lame_set_error_protection"));
   lame_set_disable_reservoir = (lame_set_disable_reservoir_t *)
       lame_lib.GetSymbol(wxT("lame_set_disable_reservoir"));
   lame_set_bWriteVbrTag = (lame_set_bWriteVbrTag_t *)
       lame_lib.GetSymbol(wxT("lame_set_bWriteVbrTag"));
 
   // These are optional
   lame_get_lametag_frame = (lame_get_lametag_frame_t *)
       lame_lib.GetSymbol(wxT("lame_get_lametag_frame"));
   lame_mp3_tags_fid = (lame_mp3_tags_fid_t *)
       lame_lib.GetSymbol(wxT("lame_mp3_tags_fid"));
#if defined(__WXMSW__)
   beWriteInfoTag = (beWriteInfoTag_t *)
       lame_lib.GetSymbol(wxT("beWriteInfoTag"));
   beVersion = (beVersion_t *)
       lame_lib.GetSymbol(wxT("beVersion"));
#endif
 
   if (!lame_init ||
      !get_lame_version ||
      !lame_init_params ||
      !lame_encode_buffer_ieee_float ||
      !lame_encode_buffer_interleaved_ieee_float ||
      !lame_encode_flush ||
      !lame_close ||
      !lame_set_in_samplerate ||
      !lame_set_out_samplerate ||
      !lame_set_num_channels ||
      !lame_set_quality ||
      !lame_set_brate ||
      !lame_set_VBR ||
      !lame_set_VBR_q ||
      !lame_set_mode ||
      !lame_set_preset ||
      !lame_set_error_protection ||
      !lame_set_disable_reservoir ||
      !lame_set_bWriteVbrTag)
   {
      wxLogMessage(wxT("Failed to find a required symbol in the LAME library."));
#if defined(__WXMSW__)
      if (beVersion) {
         be_version v;
         beVersion(&v);
 
         mBladeVersion = XO(
"You are linking to lame_enc.dll v%d.%d. This version is not compatible with Audacity %d.%d.%d.\nPlease download the latest version of 'LAME for Audacity'.")
            .Format(
               v.byMajorVersion,
               v.byMinorVersion,
               AUDACITY_VERSION,
               AUDACITY_RELEASE,
               AUDACITY_REVISION);
      }
#endif
 
      lame_lib.Unload();
      return false;
   }
#endif // DISABLE_DYNAMIC_LOADING_LAME
 
   mGF = lame_init();
   if (mGF == NULL) {
      return false;
   }
 
   return true;
}
 
void MP3Exporter::FreeLibrary()
{
   if (mGF) {
      lame_close(mGF);
      mGF = NULL;
   }
 
#ifndef DISABLE_DYNAMIC_LOADING_LAME
   lame_lib.Unload();
#endif // DISABLE_DYNAMIC_LOADING_LAME
 
   return;
}
 
wxString MP3Exporter::GetLibraryVersion()
{
#ifndef DISABLE_DYNAMIC_LOADING_LAME
   if (!mLibraryLoaded) {
      return wxT("");
   }
#endif // DISABLE_DYNAMIC_LOADING_LAME
 
   return wxString::Format(wxT("LAME %hs"), get_lame_version());
}
 
int MP3Exporter::InitializeStream(unsigned channels, int sampleRate)
{
#ifndef DISABLE_DYNAMIC_LOADING_LAME
   if (!mLibraryLoaded) {
      return -1;
   }
#endif // DISABLE_DYNAMIC_LOADING_LAME
 
   if (channels > 2) {
      return -1;
   }
 
   lame_set_error_protection(mGF, false);
   lame_set_num_channels(mGF, channels);
   lame_set_in_samplerate(mGF, sampleRate);
   lame_set_out_samplerate(mGF, sampleRate);
   lame_set_disable_reservoir(mGF, false);
   // Add the VbrTag for all types.  For ABR/VBR, a Xing tag will be created.
   // For CBR, it will be a Lame Info tag.
   lame_set_bWriteVbrTag(mGF, true);
 
   // Set the VBR quality or ABR/CBR bitrate
   switch (mMode) {
      case MODE_SET:
      {
         int preset;
 
         if (mQuality == PRESET_INSANE) {
            preset = INSANE;
         }
         //else if (mRoutine == ROUTINE_FAST) {
            else if (mQuality == PRESET_EXTREME) {
               preset = EXTREME_FAST;
            }
            else if (mQuality == PRESET_STANDARD) {
               preset = STANDARD_FAST;
            }
            else {
               preset = 1007;    // Not defined until 3.96
            }
         //}
         /*
         else {
            if (mQuality == PRESET_EXTREME) {
               preset = EXTREME;
            }
            else if (mQuality == PRESET_STANDARD) {
               preset = STANDARD;
            }
            else {
               preset = 1006;    // Not defined until 3.96
            }
         }
         */
         lame_set_preset(mGF, preset);
      }
      break;
 
      case MODE_VBR:
         lame_set_VBR(mGF, vbr_mtrh );
         lame_set_VBR_q(mGF, mQuality);
      break;
 
      case MODE_ABR:
         lame_set_preset(mGF, mBitrate );
      break;
 
      default:
         lame_set_VBR(mGF, vbr_off);
         lame_set_brate(mGF, mBitrate);
      break;
   }
 
   // Set the channel mode
   MPEG_mode mode;
 
   if (channels == 1 || mChannel == CHANNEL_MONO) {
      mode = MONO;
   }
   else if (mChannel == CHANNEL_JOINT) {
      mode = JOINT_STEREO;
   }
   else {
      mode = STEREO;
   }
   lame_set_mode(mGF, mode);
 
   int rc = lame_init_params(mGF);
   if (rc < 0) {
      return rc;
   }
 
#if 0
   dump_config(mGF);
#endif
 
   mInfoTagLen = 0;
   mEncoding = true;
 
   return mSamplesPerChunk;
}
 
int MP3Exporter::GetOutBufferSize()
{
   if (!mEncoding)
      return -1;
 
   return mOutBufferSize;
}
 
int MP3Exporter::EncodeBuffer(float inbuffer[], unsigned char outbuffer[])
{
   if (!mEncoding) {
      return -1;
   }
 
   return lame_encode_buffer_interleaved_ieee_float(mGF, inbuffer, mSamplesPerChunk,
      outbuffer, mOutBufferSize);
}
 
int MP3Exporter::EncodeRemainder(float inbuffer[], int nSamples,
                  unsigned char outbuffer[])
{
   if (!mEncoding) {
      return -1;
   }
 
   return lame_encode_buffer_interleaved_ieee_float(mGF, inbuffer, nSamples, outbuffer,
      mOutBufferSize);
}
 
int MP3Exporter::EncodeBufferMono(float inbuffer[], unsigned char outbuffer[])
{
   if (!mEncoding) {
      return -1;
   }
 
   return lame_encode_buffer_ieee_float(mGF, inbuffer,inbuffer, mSamplesPerChunk,
      outbuffer, mOutBufferSize);
}
 
int MP3Exporter::EncodeRemainderMono(float inbuffer[], int nSamples,
                  unsigned char outbuffer[])
{
   if (!mEncoding) {
      return -1;
   }
 
   return lame_encode_buffer_ieee_float(mGF, inbuffer, inbuffer, nSamples, outbuffer,
      mOutBufferSize);
}
 
int MP3Exporter::FinishStream(unsigned char outbuffer[])
{
   if (!mEncoding) {
      return -1;
   }
 
   mEncoding = false;
 
   int result = lame_encode_flush(mGF, outbuffer, mOutBufferSize);
 
#if defined(DISABLE_DYNAMIC_LOADING_LAME)
   mInfoTagLen = lame_get_lametag_frame(mGF, mInfoTagBuf, sizeof(mInfoTagBuf));
#else
   if (lame_get_lametag_frame) {
      mInfoTagLen = lame_get_lametag_frame(mGF, mInfoTagBuf, sizeof(mInfoTagBuf));
   }
#endif
 
   return result;
}
 
void MP3Exporter::CancelEncoding()
{
   mEncoding = false;
}
 
bool MP3Exporter::PutInfoTag(wxFFile & f, wxFileOffset off)
{
   if (mGF) {
      if (mInfoTagLen > 0) {
         // FIXME: TRAP_ERR Seek and writ ein MP3 exporter could fail.
         if ( !f.Seek(off, wxFromStart))
            return false;
         if (mInfoTagLen > f.Write(mInfoTagBuf, mInfoTagLen))
            return false;
      }
#if defined(__WXMSW__)
      else if (beWriteInfoTag) {
         if ( !f.Flush() )
            return false;
         // PRL:  What is the correct error check on the return value?
         beWriteInfoTag(mGF, OSOUTPUT(f.GetName()));
         mGF = NULL;
      }
#endif
      else if (lame_mp3_tags_fid != NULL) {
         lame_mp3_tags_fid(mGF, f.fp());
      }
   }
 
   if ( !f.SeekEnd() )
      return false;
 
   return true;
}
 
#if defined(__WXMSW__)
/* values for Windows */
 
wxString MP3Exporter::GetLibraryPath()
{
   wxRegKey reg(wxT("HKEY_LOCAL_MACHINE\\Software\\Lame for Audacity"));
   wxString path;
 
   if (reg.Exists()) {
      wxLogMessage(wxT("LAME registry key exists."));
      reg.QueryValue(wxT("InstallPath"), path);
   }
   else {
      wxLogMessage(wxT("LAME registry key does not exist."));
   }
 
   wxLogMessage(wxT("Library path is: ") + path);
 
   return path;
}
 
wxString MP3Exporter::GetLibraryName()
{
   return wxT("lame_enc.dll");
}
 
FileNames::FileTypes MP3Exporter::GetLibraryTypes()
{
   return {
      { XO("Only lame_enc.dll"), { wxT("lame_enc.dll") } },
      FileNames::DynamicLibraries,
      FileNames::AllFiles
   };
}
 
#elif defined(__WXMAC__)
/* values for Mac OS X */
 
wxString MP3Exporter::GetLibraryPath()
{
   wxString path;
 
   path = wxT("/Library/Application Support/audacity/libs");
   if (wxFileExists(path + wxT("/") + GetLibraryName()))
   {
        return path;
   }
 
   path = wxT("/usr/local/lib/audacity");
   if (wxFileExists(path + wxT("/") + GetLibraryName()))
   {
        return path;
   }
    
   return wxT("/Library/Application Support/audacity/libs");
}
 
wxString MP3Exporter::GetLibraryName()
{
   if (sizeof(void*) == 8)
      return wxT("libmp3lame64bit.dylib");
   return wxT("libmp3lame.dylib");
}
 
FileNames::FileTypes MP3Exporter::GetLibraryTypes()
{
   return {
      (sizeof(void*) == 8)
         ? FileNames::FileType{
              XO("Only libmp3lame64bit.dylib"), { wxT("libmp3lame64bit.dylib") }
           }
         : FileNames::FileType{
              XO("Only libmp3lame.dylib"), { wxT("libmp3lame.dylib") }
           }
      ,
      FileNames::DynamicLibraries,
      FileNames::AllFiles
   };
}
 
#else 
/* Values for Linux / Unix systems */
 
wxString MP3Exporter::GetLibraryPath()
{
   return wxT(LIBDIR);
}
 
wxString MP3Exporter::GetLibraryName()
{
   return wxT("libmp3lame.so.0");
}
 
FileNames::FileTypes MP3Exporter::GetLibraryTypes()
{
   return {
      { XO("Only libmp3lame.so.0"), { wxT("libmp3lame.so.0") } },
      { XO("Primary shared object files"), { wxT("so") }, true },
      { XO("Extended libraries"), { wxT("so*") }, true },
      FileNames::AllFiles
   };
}
#endif
 
#if 0
// Debug routine from BladeMP3EncDLL.c in the libmp3lame distro
static void dump_config(   lame_global_flags*   gfp )
{
   wxPrintf(wxT("\n\nLame_enc configuration options:\n"));
   wxPrintf(wxT("==========================================================\n"));
 
   wxPrintf(wxT("version                =%d\n"),lame_get_version( gfp ) );
   wxPrintf(wxT("Layer                  =3\n"));
   wxPrintf(wxT("mode                   ="));
   switch ( lame_get_mode( gfp ) )
   {
      case STEREO:       wxPrintf(wxT( "Stereo\n" )); break;
      case JOINT_STEREO: wxPrintf(wxT( "Joint-Stereo\n" )); break;
      case DUAL_CHANNEL: wxPrintf(wxT( "Forced Stereo\n" )); break;
      case MONO:         wxPrintf(wxT( "Mono\n" )); break;
      case NOT_SET:      /* FALLTHROUGH */
      default:           wxPrintf(wxT( "Error (unknown)\n" )); break;
   }
 
   wxPrintf(wxT("Input sample rate      =%.1f kHz\n"), lame_get_in_samplerate( gfp ) /1000.0 );
   wxPrintf(wxT("Output sample rate     =%.1f kHz\n"), lame_get_out_samplerate( gfp ) /1000.0 );
 
   wxPrintf(wxT("bitrate                =%d kbps\n"), lame_get_brate( gfp ) );
   wxPrintf(wxT("Quality Setting        =%d\n"), lame_get_quality( gfp ) );
 
   wxPrintf(wxT("Low pass frequency     =%d\n"), lame_get_lowpassfreq( gfp ) );
   wxPrintf(wxT("Low pass width         =%d\n"), lame_get_lowpasswidth( gfp ) );
 
   wxPrintf(wxT("High pass frequency    =%d\n"), lame_get_highpassfreq( gfp ) );
   wxPrintf(wxT("High pass width        =%d\n"), lame_get_highpasswidth( gfp ) );
 
   wxPrintf(wxT("No short blocks        =%d\n"), lame_get_no_short_blocks( gfp ) );
   wxPrintf(wxT("Force short blocks     =%d\n"), lame_get_force_short_blocks( gfp ) );
 
   wxPrintf(wxT("de-emphasis            =%d\n"), lame_get_emphasis( gfp ) );
   wxPrintf(wxT("private flag           =%d\n"), lame_get_extension( gfp ) );
 
   wxPrintf(wxT("copyright flag         =%d\n"), lame_get_copyright( gfp ) );
   wxPrintf(wxT("original flag          =%d\n"),   lame_get_original( gfp ) );
   wxPrintf(wxT("CRC                    =%s\n"), lame_get_error_protection( gfp ) ? wxT("on") : wxT("off") );
   wxPrintf(wxT("Fast mode              =%s\n"), ( lame_get_quality( gfp ) )? wxT("enabled") : wxT("disabled") );
   wxPrintf(wxT("Force mid/side stereo  =%s\n"), ( lame_get_force_ms( gfp ) )?wxT("enabled"):wxT("disabled") );
   wxPrintf(wxT("Padding Type           =%d\n"), (int) lame_get_padding_type( gfp ) );
   wxPrintf(wxT("Disable Reservoir      =%d\n"), lame_get_disable_reservoir( gfp ) );
   wxPrintf(wxT("Allow diff-short       =%d\n"), lame_get_allow_diff_short( gfp ) );
   wxPrintf(wxT("Interchannel masking   =%d\n"), lame_get_interChRatio( gfp ) ); // supposed to be a float, but in lib-src/lame/lame/lame.h it's int
   wxPrintf(wxT("Strict ISO Encoding    =%s\n"), ( lame_get_strict_ISO( gfp ) ) ?wxT("Yes"):wxT("No"));
   wxPrintf(wxT("Scale                  =%5.2f\n"), lame_get_scale( gfp ) );
 
   wxPrintf(wxT("VBR                    =%s, VBR_q =%d, VBR method ="),
            ( lame_get_VBR( gfp ) !=vbr_off ) ? wxT("enabled"): wxT("disabled"),
            lame_get_VBR_q( gfp ) );
 
   switch ( lame_get_VBR( gfp ) )
   {
      case vbr_off:  wxPrintf(wxT( "vbr_off\n" )); break;
      case vbr_mt :  wxPrintf(wxT( "vbr_mt \n" )); break;
      case vbr_rh :  wxPrintf(wxT( "vbr_rh \n" )); break;
      case vbr_mtrh: wxPrintf(wxT( "vbr_mtrh \n" ));  break;
      case vbr_abr:
         wxPrintf(wxT( "vbr_abr (average bitrate %d kbps)\n"), lame_get_VBR_mean_bitrate_kbps( gfp ) );
         break;
      default:
         wxPrintf(wxT("error, unknown VBR setting\n"));
         break;
   }
 
   wxPrintf(wxT("Vbr Min bitrate        =%d kbps\n"), lame_get_VBR_min_bitrate_kbps( gfp ) );
   wxPrintf(wxT("Vbr Max bitrate        =%d kbps\n"), lame_get_VBR_max_bitrate_kbps( gfp ) );
 
   wxPrintf(wxT("Write VBR Header       =%s\n"), ( lame_get_bWriteVbrTag( gfp ) ) ?wxT("Yes"):wxT("No"));
   wxPrintf(wxT("VBR Hard min           =%d\n"), lame_get_VBR_hard_min( gfp ) );
 
   wxPrintf(wxT("ATH Only               =%d\n"), lame_get_ATHonly( gfp ) );
   wxPrintf(wxT("ATH short              =%d\n"), lame_get_ATHshort( gfp ) );
   wxPrintf(wxT("ATH no                 =%d\n"), lame_get_noATH( gfp ) );
   wxPrintf(wxT("ATH type               =%d\n"), lame_get_ATHtype( gfp ) );
   wxPrintf(wxT("ATH lower              =%f\n"), lame_get_ATHlower( gfp ) );
   wxPrintf(wxT("ATH aa                 =%d\n"), lame_get_athaa_type( gfp ) );
   wxPrintf(wxT("ATH aa  loudapprox     =%d\n"), lame_get_athaa_loudapprox( gfp ) );
   wxPrintf(wxT("ATH aa  sensitivity    =%f\n"), lame_get_athaa_sensitivity( gfp ) );
 
   wxPrintf(wxT("Experimental nspsytune =%d\n"), lame_get_exp_nspsytune( gfp ) );
   wxPrintf(wxT("Experimental X         =%d\n"), lame_get_experimentalX( gfp ) );
   wxPrintf(wxT("Experimental Y         =%d\n"), lame_get_experimentalY( gfp ) );
   wxPrintf(wxT("Experimental Z         =%d\n"), lame_get_experimentalZ( gfp ) );
}
#endif
 
//----------------------------------------------------------------------------
// ExportMP3
//----------------------------------------------------------------------------
 
class ExportMP3 final : public ExportPlugin
{
public:
 
   ExportMP3();
   bool CheckFileName(wxFileName & filename, int format) override;
 
   // Required
 
   void OptionsCreate(ShuttleGui &S, int format) override;
   ProgressResult Export(AudacityProject *project,
               std::unique_ptr<ProgressDialog> &pDialog,
               unsigned channels,
               const wxFileNameWrapper &fName,
               bool selectedOnly,
               double t0,
               double t1,
               MixerSpec *mixerSpec = NULL,
               const Tags *metadata = NULL,
               int subformat = 0) override;
 
private:
 
   int AskResample(int bitrate, int rate, int lowrate, int highrate);
   unsigned long AddTags(AudacityProject *project, ArrayOf<char> &buffer, bool *endOfFile, const Tags *tags);
#ifdef USE_LIBID3TAG
   void AddFrame(struct id3_tag *tp, const wxString & n, const wxString & v, const char *name);
#endif
   int SetNumExportChannels() override;
};
 
ExportMP3::ExportMP3()
:  ExportPlugin()
{
   AddFormat();
   SetFormat(wxT("MP3"),0);
   AddExtension(wxT("mp3"),0);
   SetMaxChannels(2,0);
   SetCanMetaData(true,0);
   SetDescription(XO("MP3 Files"),0);
}
 
bool ExportMP3::CheckFileName(wxFileName & WXUNUSED(filename), int WXUNUSED(format))
{
#ifndef DISABLE_DYNAMIC_LOADING_LAME
   MP3Exporter exporter;
 
   if (!exporter.LoadLibrary(wxTheApp->GetTopWindow(), MP3Exporter::Maybe)) {
      AudacityMessageBox( XO("Could not open MP3 encoding library!") );
      gPrefs->Write(wxT("/MP3/MP3LibPath"), wxString(wxT("")));
      gPrefs->Flush();
 
      return false;
   }
#endif // DISABLE_DYNAMIC_LOADING_LAME
 
   return true;
}
 
int ExportMP3::SetNumExportChannels()
{
   bool mono;
   gPrefs->Read(wxT("/FileFormats/MP3ForceMono"), &mono, 0);
 
   return (mono)? 1 : -1;
}
 
 
ProgressResult ExportMP3::Export(AudacityProject *project,
                       std::unique_ptr<ProgressDialog> &pDialog,
                       unsigned channels,
                       const wxFileNameWrapper &fName,
                       bool selectionOnly,
                       double t0,
                       double t1,
                       MixerSpec *mixerSpec,
                       const Tags *metadata,
                       int WXUNUSED(subformat))
{
   int rate = lrint( ProjectRate::Get( *project ).GetRate());
#ifndef DISABLE_DYNAMIC_LOADING_LAME
   wxWindow *parent = ProjectWindow::Find( project );
#endif // DISABLE_DYNAMIC_LOADING_LAME
   const auto &tracks = TrackList::Get( *project );
   MP3Exporter exporter;
 
#ifdef DISABLE_DYNAMIC_LOADING_LAME
   if (!exporter.InitLibrary(wxT(""))) {
      AudacityMessageBox( XO("Could not initialize MP3 encoding library!") );
      gPrefs->Write(wxT("/MP3/MP3LibPath"), wxString(wxT("")));
      gPrefs->Flush();
 
      return ProgressResult::Cancelled;
   }
#else
   if (!exporter.LoadLibrary(parent, MP3Exporter::Maybe)) {
      AudacityMessageBox( XO("Could not open MP3 encoding library!") );
      gPrefs->Write(wxT("/MP3/MP3LibPath"), wxString(wxT("")));
      gPrefs->Flush();
 
      return ProgressResult::Cancelled;
   }
 
   if (!exporter.ValidLibraryLoaded()) {
      AudacityMessageBox( XO("Not a valid or supported MP3 encoding library!") );
      gPrefs->Write(wxT("/MP3/MP3LibPath"), wxString(wxT("")));
      gPrefs->Flush();
 
      return ProgressResult::Cancelled;
   }
#endif // DISABLE_DYNAMIC_LOADING_LAME
 
   // Retrieve preferences
   int highrate = 48000;
   int lowrate = 8000;
   int bitrate = 0;
   int brate;
   //int vmode;
   bool forceMono;
 
   gPrefs->Read(wxT("/FileFormats/MP3Bitrate"), &brate, 128);
   auto rmode = MP3RateModeSetting.ReadEnumWithDefault( MODE_CBR );
   //gPrefs->Read(wxT("/FileFormats/MP3VarMode"), &vmode, ROUTINE_FAST);
   auto cmode = MP3ChannelModeSetting.ReadEnumWithDefault( CHANNEL_STEREO );
   gPrefs->Read(wxT("/FileFormats/MP3ForceMono"), &forceMono, 0);
 
   // Set the bitrate/quality and mode
   if (rmode == MODE_SET) {
      brate = ValidateValue(setRateNames.size(), brate, PRESET_STANDARD);
      //int r = ValidateValue( varModeNames.size(), vmode, ROUTINE_FAST );
      exporter.SetMode(MODE_SET);
      exporter.SetQuality(brate/*, r*/);
   }
   else if (rmode == MODE_VBR) {
      brate = ValidateValue( varRateNames.size(), brate, QUALITY_2 );
      //int r = ValidateValue( varModeNames.size(), vmode, ROUTINE_FAST );
      exporter.SetMode(MODE_VBR);
      exporter.SetQuality(brate/*, r*/);
   }
   else if (rmode == MODE_ABR) {
      brate = ValidateIndex( fixRateValues, brate, 6 /* 128 kbps */ );
      bitrate = fixRateValues[ brate ];
      exporter.SetMode(MODE_ABR);
      exporter.SetBitrate(bitrate);
 
      if (bitrate > 160) {
         lowrate = 32000;
      }
      else if (bitrate < 32 || bitrate == 144) {
         highrate = 24000;
      }
   }
   else {
      brate = ValidateIndex( fixRateValues, brate, 6 /* 128 kbps */ );
      bitrate = fixRateValues[ brate ];
      exporter.SetMode(MODE_CBR);
      exporter.SetBitrate(bitrate);
 
      if (bitrate > 160) {
         lowrate = 32000;
      }
      else if (bitrate < 32 || bitrate == 144) {
         highrate = 24000;
      }
   }
 
   // Verify sample rate
   if (!make_iterator_range( sampRates ).contains( rate ) ||
      (rate < lowrate) || (rate > highrate)) {
      rate = AskResample(bitrate, rate, lowrate, highrate);
      if (rate == 0) {
         return ProgressResult::Cancelled;
      }
   }
 
   // Set the channel mode
   if (forceMono) {
      exporter.SetChannel(CHANNEL_MONO);
   }
   else if (cmode == CHANNEL_JOINT) {
      exporter.SetChannel(CHANNEL_JOINT);
   }
   else {
      exporter.SetChannel(CHANNEL_STEREO);
   }
 
   auto inSamples = exporter.InitializeStream(channels, rate);
   if (((int)inSamples) < 0) {
      AudacityMessageBox( XO("Unable to initialize MP3 stream") );
      return ProgressResult::Cancelled;
   }
 
   // Put ID3 tags at beginning of file
   if (metadata == NULL)
      metadata = &Tags::Get( *project );
 
   // Open file for writing
   wxFFile outFile(fName.GetFullPath(), wxT("w+b"));
   if (!outFile.IsOpened()) {
      AudacityMessageBox( XO("Unable to open target file for writing") );
      return ProgressResult::Cancelled;
   }
 
   ArrayOf<char> id3buffer;
   bool endOfFile;
   unsigned long id3len = AddTags(project, id3buffer, &endOfFile, metadata);
   if (id3len && !endOfFile) {
      if (id3len > outFile.Write(id3buffer.get(), id3len)) {
         // TODO: more precise message
         ShowExportErrorDialog("MP3:1882");
         return ProgressResult::Cancelled;
      }
   }
 
   wxFileOffset pos = outFile.Tell();
   auto updateResult = ProgressResult::Success;
   int bytes = 0;
 
   size_t bufferSize = std::max(0, exporter.GetOutBufferSize());
   if (bufferSize <= 0) {
      // TODO: more precise message
      ShowExportErrorDialog("MP3:1849");
      return ProgressResult::Cancelled;
   }
 
   ArrayOf<unsigned char> buffer{ bufferSize };
   wxASSERT(buffer);
 
   {
      auto mixer = CreateMixer(tracks, selectionOnly,
         t0, t1,
         channels, inSamples, true,
         rate, floatSample, mixerSpec);
 
      TranslatableString title;
      if (rmode == MODE_SET) {
         title = (selectionOnly ?
            XO("Exporting selected audio with %s preset") :
            XO("Exporting the audio with %s preset"))
               .Format( setRateNamesShort[brate] );
      }
      else if (rmode == MODE_VBR) {
         title = (selectionOnly ?
            XO("Exporting selected audio with VBR quality %s") :
            XO("Exporting the audio with VBR quality %s"))
               .Format( varRateNames[brate] );
      }
      else {
         title = (selectionOnly ?
            XO("Exporting selected audio at %d Kbps") :
            XO("Exporting the audio at %d Kbps"))
               .Format( bitrate );
      }
 
      InitProgress( pDialog, fName, title );
      auto &progress = *pDialog;
 
      while (updateResult == ProgressResult::Success) {
         auto blockLen = mixer->Process(inSamples);
 
         if (blockLen == 0) {
            break;
         }
 
         float *mixed = (float *)mixer->GetBuffer();
 
         if ((int)blockLen < inSamples) {
            if (channels > 1) {
               bytes = exporter.EncodeRemainder(mixed, blockLen, buffer.get());
            }
            else {
               bytes = exporter.EncodeRemainderMono(mixed, blockLen, buffer.get());
            }
         }
         else {
            if (channels > 1) {
               bytes = exporter.EncodeBuffer(mixed, buffer.get());
            }
            else {
               bytes = exporter.EncodeBufferMono(mixed, buffer.get());
            }
         }
 
         if (bytes < 0) {
            auto msg = XO("Error %ld returned from MP3 encoder")
               .Format( bytes );
            AudacityMessageBox( msg );
            updateResult = ProgressResult::Cancelled;
            break;
         }
 
         if (bytes > (int)outFile.Write(buffer.get(), bytes)) {
            // TODO: more precise message
            ShowDiskFullExportErrorDialog(fName);
            updateResult = ProgressResult::Cancelled;
            break;
         }
 
         updateResult = progress.Update(mixer->MixGetCurrentTime() - t0, t1 - t0);
      }
   }
 
   if ( updateResult == ProgressResult::Success ||
        updateResult == ProgressResult::Stopped ) {
      bytes = exporter.FinishStream(buffer.get());
 
      if (bytes < 0) {
         // TODO: more precise message
         ShowExportErrorDialog("MP3:1981");
         return ProgressResult::Cancelled;
      }
 
      if (bytes > 0) {
         if (bytes > (int)outFile.Write(buffer.get(), bytes)) {
            // TODO: more precise message
            ShowExportErrorDialog("MP3:1988");
            return ProgressResult::Cancelled;
         }
      }
 
      // Write ID3 tag if it was supposed to be at the end of the file
      if (id3len > 0 && endOfFile) {
         if (bytes > (int)outFile.Write(id3buffer.get(), id3len)) {
            // TODO: more precise message
            ShowExportErrorDialog("MP3:1997");
            return ProgressResult::Cancelled;
         }
      }
 
      // Always write the info (Xing/Lame) tag.  Until we stop supporting Lame
      // versions before 3.98, we must do this after the MP3 file has been
      // closed.
      //
      // Also, if beWriteInfoTag() is used, mGF will no longer be valid after
      // this call, so do not use it.
      if (!exporter.PutInfoTag(outFile, pos) ||
          !outFile.Flush() ||
          !outFile.Close()) {
         // TODO: more precise message
         ShowExportErrorDialog("MP3:2012");
         return ProgressResult::Cancelled;
      }
   }
 
   return updateResult;
}
 
void ExportMP3::OptionsCreate(ShuttleGui &S, int format)
{
   S.AddWindow( safenew ExportMP3Options{ S.GetParent(), format } );
}
 
int ExportMP3::AskResample(int bitrate, int rate, int lowrate, int highrate)
{
   wxDialogWrapper d(nullptr, wxID_ANY, XO("Invalid sample rate"));
   d.SetName();
   wxChoice *choice;
   ShuttleGui S(&d, eIsCreating);
 
   int selected = -1;
 
   S.StartVerticalLay();
   {
      S.SetBorder(10);
      S.StartStatic(XO("Resample"));
      {
         S.StartHorizontalLay(wxALIGN_CENTER, false);
         {
            S.AddTitle(
               ((bitrate == 0)
                  ? XO(
"The project sample rate (%d) is not supported by the MP3\nfile format. ")
                       .Format( rate )
                  : XO(
"The project sample rate (%d) and bit rate (%d kbps) combination is not\nsupported by the MP3 file format. ")
                       .Format( rate, bitrate ))
               + XO("You may resample to one of the rates below.")
            );
         }
         S.EndHorizontalLay();
 
         S.StartHorizontalLay(wxALIGN_CENTER, false);
         {
            choice = S.AddChoice(XXO("Sample Rates"),
               [&]{
                  TranslatableStrings choices;
                  for (size_t ii = 0, nn = sampRates.size(); ii < nn; ++ii) {
                     int label = sampRates[ii];
                     if (label >= lowrate && label <= highrate) {
                        choices.push_back( Verbatim( "%d" ).Format( label ) );
                        if (label <= rate)
                           selected = ii;
                     }
                  }
                  return choices;
               }(),
               std::max( 0, selected )
            );
         }
         S.EndHorizontalLay();
      }
      S.EndStatic();
 
      S.AddStandardButtons();
   }
   S.EndVerticalLay();
 
   d.Layout();
   d.Fit();
   d.SetMinSize(d.GetSize());
   d.Center();
 
   if (d.ShowModal() == wxID_CANCEL) {
      return 0;
   }
 
   return wxAtoi(choice->GetStringSelection());
}
 
#ifdef USE_LIBID3TAG
struct id3_tag_deleter {
   void operator () (id3_tag *p) const { if (p) id3_tag_delete(p); }
};
using id3_tag_holder = std::unique_ptr<id3_tag, id3_tag_deleter>;
#endif
 
// returns buffer len; caller frees
unsigned long ExportMP3::AddTags(AudacityProject *WXUNUSED(project), ArrayOf<char> &buffer, bool *endOfFile, const Tags *tags)
{
#ifdef USE_LIBID3TAG
   id3_tag_holder tp { id3_tag_new() };
 
   for (const auto &pair : tags->GetRange()) {
      const auto &n = pair.first;
      const auto &v = pair.second;
      const char *name = "TXXX";
 
      if (n.CmpNoCase(TAG_TITLE) == 0) {
         name = ID3_FRAME_TITLE;
      }
      else if (n.CmpNoCase(TAG_ARTIST) == 0) {
         name = ID3_FRAME_ARTIST;
      }
      else if (n.CmpNoCase(TAG_ALBUM) == 0) {
         name = ID3_FRAME_ALBUM;
      }
      else if (n.CmpNoCase(TAG_YEAR) == 0) {
         // LLL:  Some apps do not like the newer frame ID (ID3_FRAME_YEAR),
         //       so we add old one as well.
         AddFrame(tp.get(), n, v, "TYER");
         name = ID3_FRAME_YEAR;
      }
      else if (n.CmpNoCase(TAG_GENRE) == 0) {
         name = ID3_FRAME_GENRE;
      }
      else if (n.CmpNoCase(TAG_COMMENTS) == 0) {
         name = ID3_FRAME_COMMENT;
      }
      else if (n.CmpNoCase(TAG_TRACK) == 0) {
         name = ID3_FRAME_TRACK;
      }
 
      AddFrame(tp.get(), n, v, name);
   }
 
   tp->options &= (~ID3_TAG_OPTION_COMPRESSION); // No compression
 
   // If this version of libid3tag supports it, use v2.3 ID3
   // tags instead of the newer, but less well supported, v2.4
   // that libid3tag uses by default.
   #ifdef ID3_TAG_HAS_TAG_OPTION_ID3V2_3
   tp->options |= ID3_TAG_OPTION_ID3V2_3;
   #endif
 
   *endOfFile = false;
 
   unsigned long len;
 
   len = id3_tag_render(tp.get(), 0);
   buffer.reinit(len);
   len = id3_tag_render(tp.get(), (id3_byte_t *)buffer.get());
 
   return len;
#else //ifdef USE_LIBID3TAG
   return 0;
#endif
}
 
#ifdef USE_LIBID3TAG
void ExportMP3::AddFrame(struct id3_tag *tp, const wxString & n, const wxString & v, const char *name)
{
   struct id3_frame *frame = id3_frame_new(name);
 
   if (!n.IsAscii() || !v.IsAscii()) {
      id3_field_settextencoding(id3_frame_field(frame, 0), ID3_FIELD_TEXTENCODING_UTF_16);
   }
   else {
      id3_field_settextencoding(id3_frame_field(frame, 0), ID3_FIELD_TEXTENCODING_ISO_8859_1);
   }
 
   MallocString<id3_ucs4_t> ucs4{
      id3_utf8_ucs4duplicate((id3_utf8_t *) (const char *) v.mb_str(wxConvUTF8)) };
 
   if (strcmp(name, ID3_FRAME_COMMENT) == 0) {
      // A hack to get around iTunes not recognizing the comment.  The
      // language defaults to XXX and, since it's not a valid language,
      // iTunes just ignores the tag.  So, either set it to a valid language
      // (which one???) or just clear it.  Unfortunately, there's no supported
      // way of clearing the field, so do it directly.
      struct id3_frame *frame2 = id3_frame_new(name);
      id3_field_setfullstring(id3_frame_field(frame2, 3), ucs4.get());
      id3_field *f2 = id3_frame_field(frame2, 1);
      memset(f2->immediate.value, 0, sizeof(f2->immediate.value));
      id3_tag_attachframe(tp, frame2);
      // Now install a second frame with the standard default language = "XXX"
      id3_field_setfullstring(id3_frame_field(frame, 3), ucs4.get());
   }
   else if (strcmp(name, "TXXX") == 0) {
      id3_field_setstring(id3_frame_field(frame, 2), ucs4.get());
 
      ucs4.reset(id3_utf8_ucs4duplicate((id3_utf8_t *) (const char *) n.mb_str(wxConvUTF8)));
 
      id3_field_setstring(id3_frame_field(frame, 1), ucs4.get());
   }
   else {
      auto addr = ucs4.get();
      id3_field_setstrings(id3_frame_field(frame, 1), 1, &addr);
   }
 
   id3_tag_attachframe(tp, frame);
}
#endif
 
static Exporter::RegisteredExportPlugin sRegisteredPlugin{ "MP3",
   []{ return std::make_unique< ExportMP3 >(); }
};
 
//----------------------------------------------------------------------------
// Return library version
//----------------------------------------------------------------------------
 
TranslatableString GetMP3Version(wxWindow *parent, bool prompt)
{
   MP3Exporter exporter;
   auto versionString = XO("MP3 export library not found");
 
#ifndef DISABLE_DYNAMIC_LOADING_LAME
   if (prompt) {
      exporter.FindLibrary(parent);
   }
 
   if (exporter.LoadLibrary(parent, prompt ? MP3Exporter::Yes : MP3Exporter::No)) {
#endif // DISABLE_DYNAMIC_LOADING_LAME
      versionString = Verbatim( exporter.GetLibraryVersion() );
#ifdef MP3_EXPORT_BUILT_IN
      versionString.Join( XO("(Built-in)"), " " );
#endif
 
#ifndef DISABLE_DYNAMIC_LOADING_LAME
   }
#endif // DISABLE_DYNAMIC_LOADING_LAME
 
   return versionString;
}