Remove the need for SDL_mixer

SDL_mixer is not in the standard SDL distribution. The mixing is now
done using regular SDL_Audio functions. AudioManager is converted to a
singleton and std::shared_ptrs are used for all Sound objects. Note that
for GCC "-std=c++11" might need to be added to the CMAKE_CXX_FLAGS.

src/AudioManager.cpp

@@ -1,69 +1,100 @@
 #include "AudioManager.h"
 
 #include "Log.h"
-#include "SDL.h"
-#include "SDL_mixer.h"
-#include <iostream>
-#include "Sound.h"
-#include <vector>
 
-namespace AudioManager
+
+std::vector<std::shared_ptr<Sound>> AudioManager::sSoundVector;
+std::shared_ptr<AudioManager> AudioManager::sInstance;
+SDL_AudioSpec AudioManager::sAudioFormat;
+
+
+void AudioManager::mixAudio(void *unused, Uint8 *stream, int len)
 {
-	std::vector<Sound*> sSoundVector;
+	bool stillPlaying = false;
 
-	bool sInitialized = false;
-
-	void init()
+	//iterate through all our samples
+	std::vector<std::shared_ptr<Sound>>::const_iterator soundIt = sSoundVector.cbegin();
+	while (soundIt != sSoundVector.cend())
 	{
-		int result = Mix_OpenAudio(MIX_DEFAULT_FREQUENCY, AUDIO_S16SYS, 2, 1024);
-
-		if(result == -1)
+		std::shared_ptr<Sound> sound = *soundIt;
+		if(sound->isPlaying())
 		{
-			LOG(LogError) << "Error initializing AudioManager!\n	" << Mix_GetError();
-			return;
-		}
-
-		sInitialized = true;
-
-		for(unsigned int i = 0; i < sSoundVector.size(); i++)
-		{
-			sSoundVector.at(i)->init();
-		}
-	}
-
-	void registerSound(Sound* sound)
-	{
-		sSoundVector.push_back(sound);
-	}
-
-	void unregisterSound(Sound* sound)
-	{
-		for(unsigned int i = 0; i < sSoundVector.size(); i++)
-		{
-			if(sSoundVector.at(i) == sound)
+			//calculate rest length of current sample
+			Uint32 restLength = (sound->getLength() - sound->getPosition());
+			if (restLength > len) {
+				//if stream length is smaller than smaple lenght, clip it
+				restLength = len;
+			}
+			//mix sample into stream
+			SDL_MixAudio(stream, &(sound->getData()[sound->getPosition()]), restLength, SDL_MIX_MAXVOLUME);
+			if (sound->getPosition() + restLength >= sound->getLength())
 			{
-				sSoundVector.erase(sSoundVector.begin() + i);
-				return;
+				//if the position is beyond the end of the buffer, stop playing the sample
+				sound->stop();
+			}
+			else 
+			{
+				//sample hasn't ended yet
+				sound->setPosition(sound->getPosition() + restLength);
+				stillPlaying = true;
 			}
 		}
-
-		LOG(LogError) << "AudioManager Error - tried to unregister a sound that wasn't registered!";
+		//advance to next sound
+		++soundIt;
 	}
-
-	void deinit()
-	{
-		for(unsigned int i = 0; i < sSoundVector.size(); i++)
-		{
-			sSoundVector.at(i)->deinit();
-		}
-
-		Mix_CloseAudio();
-
-		sInitialized = false;
-	}
-
-	bool isInitialized()
-	{
-		return sInitialized;
+	//we have processed all samples. check if some will still be playing
+	if (!stillPlaying) {
+		//no. pause audio till a Sound::play() wakes us up
+		SDL_PauseAudio(1);
 	}
 }
+
+AudioManager::AudioManager()
+{
+	//Set up format and callback. Play 16-bit stereo audio at 44.1Khz
+	sAudioFormat.freq = 44100;
+	sAudioFormat.format = AUDIO_S16;
+	sAudioFormat.channels = 2;
+	sAudioFormat.samples = 1024;
+	sAudioFormat.callback = mixAudio;
+	sAudioFormat.userdata = NULL;
+
+	//Open the audio device and pause
+	if (SDL_OpenAudio(&sAudioFormat, NULL) < 0) {
+		LOG(LogError) << "AudioManager Error - Unable to open SDL audio: " << SDL_GetError() << std::endl;
+	}
+}
+
+AudioManager::~AudioManager()
+{
+	SDL_PauseAudio(1);
+	SDL_CloseAudio();
+}
+
+void AudioManager::registerSound(std::shared_ptr<Sound> & sound)
+{
+	//check if an AudioManager instance is already created, if not create one
+	if (sInstance == nullptr) {
+		sInstance = std::shared_ptr<AudioManager>(new AudioManager);
+	}
+	sSoundVector.push_back(sound);
+}
+
+void AudioManager::unregisterSound(std::shared_ptr<Sound> & sound)
+{
+	for(unsigned int i = 0; i < sSoundVector.size(); i++)
+	{
+		if(sSoundVector.at(i) == sound)
+		{
+			sSoundVector.erase(sSoundVector.begin() + i);
+			return;
+		}
+	}
+	LOG(LogError) << "AudioManager Error - tried to unregister a sound that wasn't registered!";
+}
+
+void AudioManager::play()
+{
+	//unpause audio, the mixer will figure out if samples need to be played...
+	SDL_PauseAudio(0);
+}

src/AudioManager.h

@@ -1,17 +1,31 @@
 #ifndef _AUDIOMANAGER_H_
 #define _AUDIOMANAGER_H_
 
-class Sound;
+#include <vector>
+#include <memory>
 
-namespace AudioManager
+#include "SDL_audio.h"
+
+#include "Sound.h"
+
+
+class AudioManager
 {
-	void registerSound(Sound* sound);
-	void unregisterSound(Sound* sound);
+	static SDL_AudioSpec sAudioFormat;
+	static std::vector<std::shared_ptr<Sound>> sSoundVector;
+	static std::shared_ptr<AudioManager> sInstance;
 
-	bool isInitialized();
+	static void mixAudio(void *unused, Uint8 *stream, int len);
 
-	void init();
-	void deinit();
-}
+	AudioManager();
+
+public:
+	static void registerSound(std::shared_ptr<Sound> & sound);
+	static void unregisterSound(std::shared_ptr<Sound> & sound);
+
+	static void play();
+
+	virtual ~AudioManager();
+};
 
 #endif

src/Sound.cpp

@@ -1,26 +1,19 @@
 #include "Sound.h"
-#include <iostream>
 #include "AudioManager.h"
 #include "Log.h"
 
-Sound::Sound(std::string path)
+
+Sound::Sound(const std::string & path) : mSampleData(NULL), mSamplePos(0), mSampleLength(0), playing(false)
 {
-	mSound = NULL;
-	mChannel = -1;
-
-	AudioManager::registerSound(this);
-
 	loadFile(path);
 }
 
 Sound::~Sound()
 {
 	deinit();
-
-	AudioManager::unregisterSound(this);
 }
 
-void Sound::loadFile(std::string path)
+void Sound::loadFile(const std::string & path)
 {
 	mPath = path;
 	init();
@@ -28,51 +21,104 @@ void Sound::loadFile(std::string path)
 
 void Sound::init()
 {
-	if(!AudioManager::isInitialized())
-		return;
-
-	if(mSound != NULL)
+	if(mSampleData != NULL)
 		deinit();
 
 	if(mPath.empty())
 		return;
 
-	mSound = Mix_LoadWAV(mPath.c_str());
-
-	if(mSound == NULL)
-	{
-		LOG(LogError) << "Error loading sound \"" << mPath << "\"!\n" << "	" << Mix_GetError();
+	//load wav file via SDL
+	SDL_AudioSpec wave;
+	Uint8 * data = NULL;
+    Uint32 dlen = 0;
+	if (SDL_LoadWAV(mPath.c_str(), &wave, &data, &dlen) == NULL) {
+		LOG(LogError) << "Error loading sound \"" << mPath << "\"!\n" << "	" << SDL_GetError();
+		return;
 	}
+	//build conversion buffer
+	SDL_AudioCVT cvt;
+    SDL_BuildAudioCVT(&cvt, wave.format, wave.channels, wave.freq, AUDIO_S16, 2, 44100);
+	//copy data to conversion buffer
+	cvt.len = dlen;
+    cvt.buf = new Uint8[cvt.len * cvt.len_mult];
+    memcpy(cvt.buf, data, dlen);
+	//convert buffer to stereo, 16bit, 44.1kHz
+    if (SDL_ConvertAudio(&cvt) < 0) {
+		LOG(LogError) << "Error converting sound \"" << mPath << "\" to 44.1kHz, 16bit, stereo format!\n" << "	" << SDL_GetError();
+		delete[] cvt.buf;
+	}
+	else {
+		//worked. set up member data
+		SDL_LockAudio();
+		mSampleData = cvt.buf;
+		mSampleLength = cvt.len_cvt;
+		mSamplePos = 0;
+		mSampleFormat.channels = 2;
+		mSampleFormat.freq = 44100;
+		mSampleFormat.format = AUDIO_S16;
+		SDL_UnlockAudio();
+	}
+	//free wav data now
+    SDL_FreeWAV(data);
 }
 
 void Sound::deinit()
 {
-	if(mSound != NULL)
+	playing = false;
+
+	if(mSampleData != NULL)
 	{
-		Mix_FreeChunk(mSound);
-		mSound = NULL;
+		SDL_LockAudio();
+		delete[] mSampleData;
+		mSampleData = NULL;
+		mSampleLength = 0;
+		mSamplePos = 0;
+		SDL_UnlockAudio();
 	}
 }
 
 void Sound::play()
 {
-	if(mSound == NULL)
+	if(mSampleData == NULL)
 		return;
 
-	mChannel = -1;
+	//flag our sample as playing
+	playing = true;
+	//tell the AudioManager to start playing samples
+	AudioManager::play();
+}
 
-	mChannel = Mix_PlayChannel(-1, mSound, 0);
-	if(mChannel == -1)
-	{
-		LOG(LogError) << "Error playing sound!\n	" << Mix_GetError();
+bool Sound::isPlaying() const
+{
+	return playing;
+}
+
+void Sound::stop()
+{
+	//flag our sample as playing and rewind its position
+	playing = false;
+	mSamplePos = 0;
+}
+
+const Uint8 * Sound::getData() const
+{
+	return mSampleData;
+}
+
+Uint32 Sound::getPosition() const
+{
+	return mSamplePos;
+}
+
+void Sound::setPosition(Uint32 newPosition)
+{
+	mSamplePos = newPosition;
+	if (mSamplePos >= mSampleLength) {
+		mSamplePos = 0;
 	}
 }
 
-bool Sound::isPlaying()
+Uint32 Sound::getLength() const
 {
-	if(mChannel != -1 && Mix_Playing(mChannel))
-		return true;
-	else
-		return false;
-}
-
+	return mSampleLength;
+}

src/Sound.h

@@ -2,25 +2,35 @@
 #define _SOUND_H_
 
 #include <string>
-#include "SDL_mixer.h"
+#include "SDL_audio.h"
+
 
 class Sound
 {
+	std::string mPath;
+    SDL_AudioSpec mSampleFormat;
+	Uint8 * mSampleData;
+    Uint32 mSamplePos;
+    Uint32 mSampleLength;
+	bool playing;
+
 public:
-	Sound(std::string path = "");
+	Sound(const std::string & path = "");
 	~Sound();
 
 	void init();
 	void deinit();
 
-	void loadFile(std::string path);
+	void loadFile(const std::string & path);
 
 	void play();
-	bool isPlaying();
-private:
-	std::string mPath;
-	int mChannel;
-	Mix_Chunk* mSound;
+	bool isPlaying() const;
+	void stop();
+
+	const Uint8 * getData() const;
+	Uint32 getPosition() const;
+	void setPosition(Uint32 newPosition);
+	Uint32 getLength() const;
 };
 
 #endif

src/Window.cpp

@@ -51,7 +51,6 @@ void Window::render()
 
 void Window::init()
 {
-	AudioManager::init();
 	mInputManager->init();
 	Renderer::init(0, 0);
 
@@ -68,7 +67,6 @@ void Window::deinit()
 		mGuiStack.at(i)->deinit();
 	}
 
-	AudioManager::deinit();
 	mInputManager->deinit();
 	Renderer::deinit();
 }

src/components/GuiFastSelect.cpp

@@ -8,7 +8,7 @@ const int GuiFastSelect::SCROLLSPEED = 100;
 const int GuiFastSelect::SCROLLDELAY = 507;
 
 GuiFastSelect::GuiFastSelect(Window* window, GuiGameList* parent, GuiList<FileData*>* list, char startLetter, GuiBoxData data, 
-	int textcolor, Sound* scrollsound, Font* font) : Gui(window)
+	int textcolor, std::shared_ptr<Sound> & scrollsound, Font* font) : Gui(window)
 {
 	mLetterID = LETTERS.find(toupper(startLetter));
 	if(mLetterID == std::string::npos)

src/components/GuiFastSelect.h

@@ -13,7 +13,7 @@ class GuiGameList;
 class GuiFastSelect : public Gui
 {
 public:
-	GuiFastSelect(Window* window, GuiGameList* parent, GuiList<FileData*>* list, char startLetter, GuiBoxData data, int textcolor, Sound* scrollsound, Font* font);
+	GuiFastSelect(Window* window, GuiGameList* parent, GuiList<FileData*>* list, char startLetter, GuiBoxData data, int textcolor, std::shared_ptr<Sound> & scrollsound, Font* font);
 	~GuiFastSelect();
 
 	void input(InputConfig* config, Input input);
@@ -39,7 +39,7 @@ private:
 	int mScrollTimer, mScrollOffset;
 	bool mScrolling;
 
-	Sound* mScrollSound;
+	std::shared_ptr<Sound> mScrollSound;
 	Font* mFont;
 };
 

src/components/GuiList.cpp

@@ -269,7 +269,7 @@ void GuiList<listType>::setSelection(int i)
 }
 
 template <typename listType>
-void GuiList<listType>::setScrollSound(Sound* sound)
+void GuiList<listType>::setScrollSound(std::shared_ptr<Sound> & sound)
 {
 	mScrollSound = sound;
 }

src/components/GuiList.h

@@ -34,7 +34,7 @@ public:
 	void setSelectorColor(unsigned int selectorColor);
 	void setSelectedTextColor(unsigned int selectedColor);
 	void setCentered(bool centered);
-	void setScrollSound(Sound* sound);
+	void setScrollSound(std::shared_ptr<Sound> & sound);
 	void setTextOffsetX(int textoffsetx);
 
 	int getObjectCount();
@@ -71,7 +71,7 @@ private:
 
 	std::vector<ListRow> mRowVector;
 	int mSelection;
-	Sound* mScrollSound;
+	std::shared_ptr<Sound> mScrollSound;
 };
 
 #include "GuiList.cpp"

src/components/GuiTheme.cpp

@@ -23,7 +23,7 @@ float GuiTheme::getFloat(std::string name)
 	return mFloatMap[name];
 }
 
-Sound* GuiTheme::getSound(std::string name)
+std::shared_ptr<Sound> & GuiTheme::getSound(std::string name)
 {
 	return mSoundMap[name];
 }
@@ -63,10 +63,16 @@ GuiTheme::GuiTheme(Window* window, bool detailed, std::string path) : Gui(window
 {
 	mDetailed = detailed;
 
-	mSoundMap["menuScroll"] = new Sound();
-	mSoundMap["menuSelect"] = new Sound();
-	mSoundMap["menuBack"] = new Sound();
-	mSoundMap["menuOpen"] = new Sound();
+	mSoundMap["menuScroll"] = std::shared_ptr<Sound>(new Sound);
+	mSoundMap["menuSelect"] = std::shared_ptr<Sound>(new Sound);
+	mSoundMap["menuBack"] = std::shared_ptr<Sound>(new Sound);
+	mSoundMap["menuOpen"] = std::shared_ptr<Sound>(new Sound);
+
+	//register all sound with the audiomanager
+	AudioManager::registerSound(mSoundMap["menuScroll"]);
+	AudioManager::registerSound(mSoundMap["menuSelect"]);
+	AudioManager::registerSound(mSoundMap["menuBack"]);
+	AudioManager::registerSound(mSoundMap["menuOpen"]);
 
 	mListFont = NULL;
 	mDescFont = NULL;

src/components/GuiTheme.h

@@ -1,10 +1,12 @@
 #ifndef _GUITHEME_H_
 #define _GUITHEME_H_
 
+#include <memory>
+
 #include "../Gui.h"
 #include "../pugiXML/pugixml.hpp"
 #include "GuiBox.h"
-#include "../Sound.h"
+#include "../AudioManager.h"
 #include "../Font.h"
 
 //This class loads an XML-defined list of Guis.
@@ -26,7 +28,7 @@ public:
 	unsigned int getColor(std::string name);
 	bool getBool(std::string name);
 	float getFloat(std::string name);
-	Sound* getSound(std::string name);
+	std::shared_ptr<Sound> & getSound(std::string name);
 	std::string getString(std::string name);
 
 	Font* getListFont();
@@ -53,7 +55,7 @@ private:
 	std::map<std::string, unsigned int> mColorMap;
 	std::map<std::string, bool> mBoolMap;
 	std::map<std::string, float> mFloatMap;
-	std::map<std::string, Sound*> mSoundMap;
+	std::map<std::string, std::shared_ptr<Sound>> mSoundMap;
 	std::map<std::string, std::string> mStringMap;
 
 	GuiBoxData mBoxData;

src/main.cpp

@@ -119,10 +119,6 @@ int main(int argc, char* argv[])
 		return 1;
 	}
 
-
-	//initialize audio
-	AudioManager::init();
-
 	Window window; //don't call Window.init() because we manually pass the resolution to Renderer::init
 	window.getInputManager()->init();
 
@@ -139,7 +135,7 @@ int main(int argc, char* argv[])
 		if(SystemData::sSystemVector.size() == 0) //if it exists but was empty, notify the user and quit
 		{
 			std::cerr << "A system config file in " << SystemData::getConfigPath() << " was found, but contained no systems.\n";
-			std::cerr << "Does at least one system have a game presesnt?\n";
+			std::cerr << "Does at least one system have a game present?\n";
 			running = false;
 		}else{
 			//choose which GUI to open depending on Input configuration
@@ -222,7 +218,6 @@ int main(int argc, char* argv[])
 		Log::flush();
 	}
 
-	AudioManager::deinit();
 	Renderer::deinit();
 	SystemData::deleteSystems();
 

src/platform.cpp

@@ -3,13 +3,10 @@
 
 std::string getHomePath()
 {
-	#ifdef _WIN32
-		return "C:\\";
-	#else
-		const char* home = getenv("HOME");
-		if(home == NULL)
-			return "";
-		else
-			return home;
-	#endif
+	//this gives you something like "/home/YOUR_USERNAME" on Linux and "C:\Users\YOUR_USERNAME\" on Windows
+	const char* home = getenv("HOME");
+	if(home == NULL)
+		return "";
+	else
+		return home;
 }