From c7cac63a384bf096aad41d6d5c3df2252c22d81b Mon Sep 17 00:00:00 2001
From: Thomas Jentzsch <tjentzsch@yahoo.de>
Date: Sat, 3 Sep 2022 20:56:38 +0200
Subject: [PATCH] added WAV file volume adjustment (resolves #77)

---
 src/common/SoundSDL2.cxx | 41 +++++++++++++++++++++++++++++++---------
 src/common/SoundSDL2.hxx | 10 ++++++++--
 src/emucore/KidVid.cxx   | 15 +++++++++++----
 3 files changed, 51 insertions(+), 15 deletions(-)

diff --git a/src/common/SoundSDL2.cxx b/src/common/SoundSDL2.cxx
index 4b619566f..f7b3e256e 100644
--- a/src/common/SoundSDL2.cxx
+++ b/src/common/SoundSDL2.cxx
@@ -405,17 +405,13 @@ void SoundSDL2::callback(void* udata, uInt8* stream, int len)
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 bool SoundSDL2::playWav(const char* fileName, uInt32 position, uInt32 length)
 {
-  // ToDos:
-  // - volume (requires callback using SDL_MixAudio)
-  // - (un)mute
-  SDL_AudioSpec wavSpec;
   uInt32 wavLength{0};
 
   // Stop any playing WAVs
   stopWav();
 
   // Load WAV file
-  SDL_AudioSpec* result = SDL_LoadWAV(fileName, &wavSpec, &myWavBuffer, &wavLength);
+  SDL_AudioSpec* result = SDL_LoadWAV(fileName, &myWavSpec, &myWavBuffer, &wavLength);
   if(result == nullptr || position > wavLength)
     return false;
 
@@ -423,18 +419,24 @@ bool SoundSDL2::playWav(const char* fileName, uInt32 position, uInt32 length)
     ? std::min(length, wavLength - position)
     : wavLength;
 
+  // Set the callback function
+  myWavSpec.callback = wavCallback;
+  myWavSpec.userdata = nullptr;
+
+  myWavPos = myWavBuffer + position;
+  myWavLen = length;
+
   // Open audio device
   const char* device = myDeviceId ? myDevices.at(myDeviceId).first.c_str() : nullptr;
 
-  myWavDevice = SDL_OpenAudioDevice(device, 0, &wavSpec, nullptr, 0);
+  myWavDevice = SDL_OpenAudioDevice(device, 0, &myWavSpec, nullptr, 0);
   if(!myWavDevice)
     return false;
 
   // Play audio
-  int success = SDL_QueueAudio(myWavDevice, myWavBuffer + position, length);
   SDL_PauseAudioDevice(myWavDevice, 0);
 
-  return success == 0;
+  return true;
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
@@ -452,7 +454,28 @@ void SoundSDL2::stopWav()
 
 uInt32 SoundSDL2::wavSize() const
 {
-  return myWavBuffer ? SDL_GetQueuedAudioSize(myWavDevice) : 0;
+  return myWavBuffer ? myWavLen /*SDL_GetQueuedAudioSize(myWavDevice)*/ : 0;
 }
 
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+void SoundSDL2::wavCallback(void* udata, uInt8* stream, int len)
+{
+  SDL_memset(stream, myWavSpec.silence, len);
+  if(myWavLen)
+  {
+    if(static_cast<uInt32>(len) > myWavLen)
+      len = myWavLen;
+    // Mix volume adjusted WAV into silent buffer
+    SDL_MixAudioFormat(stream, myWavPos, myWavSpec.format, len,
+                       SDL_MIX_MAXVOLUME * myVolumeFactor);
+    myWavPos += len;
+    myWavLen -= len;
+  }
+}
+
+float SoundSDL2::myVolumeFactor = 0xffff;
+SDL_AudioSpec SoundSDL2::myWavSpec;   // audio output format
+uInt8* SoundSDL2::myWavPos = nullptr; // pointer to the audio buffer to be played
+uInt32 SoundSDL2::myWavLen = 0;       // remaining length of the sample we have to play
+
 #endif  // SOUND_SUPPORT
diff --git a/src/common/SoundSDL2.hxx b/src/common/SoundSDL2.hxx
index 20a58429a..567dd08ad 100644
--- a/src/common/SoundSDL2.hxx
+++ b/src/common/SoundSDL2.hxx
@@ -164,7 +164,7 @@ class SoundSDL2 : public Sound
 
     // Current volume as a percentage (0 - 100)
     uInt32 myVolume{100};
-    float myVolumeFactor{0xffff};
+    static float myVolumeFactor;
 
     // Audio specification structure
     SDL_AudioSpec myHardwareSpec;
@@ -184,14 +184,20 @@ class SoundSDL2 : public Sound
 
     AudioSettings& myAudioSettings;
 
+    // WAV file sound variables
     SDL_AudioDeviceID myWavDevice{0};
     uInt8* myWavBuffer{nullptr};
 
+    static SDL_AudioSpec myWavSpec; // audio output format
+    static uInt8* myWavPos; // pointer to the audio buffer to be played
+    static uInt32 myWavLen; // remaining length of the sample we have to play
+
     string myAboutString;
 
   private:
-    // Callback function invoked by the SDL Audio library when it needs data
+    // Callback functions invoked by the SDL Audio library when it needs data
     static void callback(void* udata, uInt8* stream, int len);
+    static void wavCallback(void* udata, uInt8* stream, int len);
 
     // Following constructors and assignment operators not supported
     SoundSDL2() = delete;
diff --git a/src/emucore/KidVid.cxx b/src/emucore/KidVid.cxx
index 9d4a6e137..351cee40c 100644
--- a/src/emucore/KidVid.cxx
+++ b/src/emucore/KidVid.cxx
@@ -162,14 +162,17 @@ void KidVid::openSampleFiles()
     mySampleFile = myBaseDir + fileNames[i];
 
     std::ifstream f1, f2;
-    f1.open(mySampleFile, std::ios::binary);
-    f2.open(myBaseDir + "KVSHARED.WAV", std::ios::binary);
+    f1.open(mySampleFile);
+    f2.open(myBaseDir + "KVSHARED.WAV");
 
     myFilesFound = f1.is_open() && f2.is_open();
 
+#ifdef DEBUG_BUILD
     if(myFilesFound)
-      cerr << "found file: " << fileNames[i] << endl
+      cerr << endl
+           << "found file: " << fileNames[i] << endl
            << "found file: " << "KVSHARED.WAV" << endl;
+#endif
 
     mySongLength = 0;
     mySongPointer = firstSongPointer[i];
@@ -185,11 +188,15 @@ void KidVid::setNextSong()
     myBeep = (ourSongPositions[mySongPointer] & 0x80) == 0;
 
     const uInt8 temp = ourSongPositions[mySongPointer] & 0x7f;
-    mySongLength = ourSongStart[temp+1] - ourSongStart[temp];
+    mySongLength = ourSongStart[temp + 1] - ourSongStart[temp];
 
     // Play the WAV file
     const string fileName = (temp < 10) ? myBaseDir + "KVSHARED.WAV" : mySampleFile;
     mySound.playWav(fileName.c_str(), ourSongStart[temp], mySongLength);
+#ifdef DEBUG_BUILD
+    cerr << fileName << ": " << (ourSongPositions[mySongPointer] & 0x7f) << endl;
+#endif
+
 
     mySongPlaying = myTapeBusy = true;
     ++mySongPointer;