Created SdlMixerImpl. Added setSampleRate method to Audio::MixerImpl. Updated and removed mixer code in OSystem_SDL for using SdlMixerImpl.

svn-id: r49602

2 files changed, 286 insertions, 0 deletions

diff --git a/backends/mixer/sdl/sdl-mixer.cpp b/backends/mixer/sdl/sdl-mixer.cpp
new file mode 100644
index 0000000000..e56b64f8ec
--- /dev/null
+++ b/backends/mixer/sdl/sdl-mixer.cpp
@@ -0,0 +1,205 @@
+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * $URL$
+ * $Id$
+ *
+ */
+
+#if defined(WIN32) || defined(UNIX) || defined(MACOSX)
+
+#include "backends/mixer/sdl/sdl-mixer.h"
+
+#include "common/config-manager.h"
+
+//#define SAMPLES_PER_SEC 11025
+#define SAMPLES_PER_SEC 22050
+//#define SAMPLES_PER_SEC 44100
+
+SdlMixerImpl::SdlMixerImpl(OSystem *system)
+	:
+#if MIXER_DOUBLE_BUFFERING
+	_soundMutex(0), _soundCond(0), _soundThread(0),
+	_soundThreadIsRunning(false), _soundThreadShouldQuit(false),
+#endif
+	MixerImpl(system, SAMPLES_PER_SEC) {
+	SDL_AudioSpec desired;
+
+	// Determine the desired output sampling frequency.
+	uint32 samplesPerSec = 0;
+	if (ConfMan.hasKey("output_rate"))
+		samplesPerSec = ConfMan.getInt("output_rate");
+	if (samplesPerSec <= 0)
+		samplesPerSec = SAMPLES_PER_SEC;
+
+	// Determine the sample buffer size. We want it to store enough data for
+	// at least 1/16th of a second (though at most 8192 samples). Note
+	// that it must be a power of two. So e.g. at 22050 Hz, we request a
+	// sample buffer size of 2048.
+	uint32 samples = 8192;
+	while (samples * 16 > samplesPerSec * 2)
+		samples >>= 1;
+
+	memset(&desired, 0, sizeof(desired));
+	desired.freq = samplesPerSec;
+	desired.format = AUDIO_S16SYS;
+	desired.channels = 2;
+	desired.samples = (uint16)samples;
+	desired.callback = mixSdlCallback;
+	desired.userdata = this;
+
+	if (SDL_OpenAudio(&desired, &_obtainedRate) != 0) {
+		warning("Could not open audio device: %s", SDL_GetError());
+
+		setSampleRate(samplesPerSec);
+
+		setReady(false);
+	} else {
+		// Note: This should be the obtained output rate, but it seems that at
+		// least on some platforms SDL will lie and claim it did get the rate
+		// even if it didn't. Probably only happens for "weird" rates, though.
+		samplesPerSec = _obtainedRate.freq;
+		debug(1, "Output sample rate: %d Hz", samplesPerSec);
+
+		setSampleRate(samplesPerSec);
+
+		setReady(true);
+
+#if MIXER_DOUBLE_BUFFERING
+		initThreadedMixer(_obtainedRate.samples * 4);
+#endif
+
+		// start the sound system
+		SDL_PauseAudio(0);
+	}
+}
+
+SdlMixerImpl::~SdlMixerImpl() {
+	setReady(false);
+
+	SDL_CloseAudio();
+
+#if MIXER_DOUBLE_BUFFERING
+	deinitThreadedMixer();
+#endif
+}
+
+#if MIXER_DOUBLE_BUFFERING
+
+void SdlMixerImpl::mixerProducerThread() {
+	byte nextSoundBuffer;
+
+	SDL_LockMutex(_soundMutex);
+	while (true) {
+		// Wait till we are allowed to produce data
+		SDL_CondWait(_soundCond, _soundMutex);
+
+		if (_soundThreadShouldQuit)
+			break;
+
+		// Generate samples and put them into the next buffer
+		nextSoundBuffer = _activeSoundBuf ^ 1;
+		mixCallback(_soundBuffers[nextSoundBuffer], _soundBufSize);
+
+		// Swap buffers
+		_activeSoundBuf = nextSoundBuffer;
+	}
+	SDL_UnlockMutex(_soundMutex);
+}
+
+int SDLCALL SdlMixerImpl::mixerProducerThreadEntry(void *arg) {
+	SdlMixerImpl *mixer = (SdlMixerImpl *)arg;
+	assert(mixer);
+	mixer->mixerProducerThread();
+	return 0;
+}
+
+
+void SdlMixerImpl::initThreadedMixer(uint bufSize) {
+	_soundThreadIsRunning = false;
+	_soundThreadShouldQuit = false;
+
+	// Create mutex and condition variable
+	_soundMutex = SDL_CreateMutex();
+	_soundCond = SDL_CreateCond();
+
+	// Create two sound buffers
+	_activeSoundBuf = 0;
+	_soundBufSize = bufSize;
+	_soundBuffers[0] = (byte *)calloc(1, bufSize);
+	_soundBuffers[1] = (byte *)calloc(1, bufSize);
+
+	_soundThreadIsRunning = true;
+
+	// Finally start the thread
+	_soundThread = SDL_CreateThread(mixerProducerThreadEntry, this);
+}
+
+void SdlMixerImpl::deinitThreadedMixer() {
+	// Kill thread?? _soundThread
+
+	if (_soundThreadIsRunning) {
+		// Signal the producer thread to end, and wait for it to actually finish.
+		_soundThreadShouldQuit = true;
+		SDL_CondBroadcast(_soundCond);
+		SDL_WaitThread(_soundThread, NULL);
+
+		// Kill the mutex & cond variables.
+		// Attention: AT this point, the mixer callback must not be running
+		// anymore, else we will crash!
+		SDL_DestroyMutex(_soundMutex);
+		SDL_DestroyCond(_soundCond);
+
+		_soundThreadIsRunning = false;
+
+		free(_soundBuffers[0]);
+		free(_soundBuffers[1]);
+	}
+}
+
+
+void SdlMixerImpl::mixSdlCallback(void *arg, byte *samples, int len) {
+	SdlMixerImpl *mixer = (SdlMixerImpl *)arg;
+	assert(mixer);
+
+	assert((int)mixer->getSoundBufSize() == len);
+
+	// Lock mutex, to ensure our data is not overwritten by the producer thread
+	g_system->lockMutex((OSystem::MutexRef)mixer->getSoundMutex());
+
+	// Copy data from the current sound buffer
+	memcpy(samples, mixer->getActiveSoundBuf(), len);
+
+	// Unlock mutex and wake up the produced thread
+	g_system->unlockMutex((OSystem::MutexRef)mixer->getSoundMutex());
+	SDL_CondSignal(mixer->getSoundCond());
+}
+
+#else
+
+void SdlMixerImpl::mixSdlCallback(void *sys, byte *samples, int len) {
+	Audio::MixerImpl *mixer = (Audio::MixerImpl *)sys;
+	assert(mixer);
+	mixer->mixCallback(samples, len);
+}
+
+#endif
+
+#endif
diff --git a/backends/mixer/sdl/sdl-mixer.h b/backends/mixer/sdl/sdl-mixer.h
new file mode 100644
index 0000000000..272c3934a6
--- /dev/null
+++ b/backends/mixer/sdl/sdl-mixer.h
@@ -0,0 +1,81 @@
+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * $URL$
+ * $Id$
+ *
+ */
+
+#ifndef BACKENDS_MIXER_SDL_H
+#define BACKENDS_MIXER_SDL_H
+
+#if defined(__SYMBIAN32__)
+#include <esdl\SDL.h>
+#else
+#include <SDL.h>
+#endif
+
+#include "sound/mixer_intern.h"
+
+#if defined(MACOSX)
+// On Mac OS X, we need to double buffer the audio buffer, else anything
+// which produces sampled data with high latency (like the MT-32 emulator)
+// will sound terribly.
+// This could be enabled for more / most ports in the future, but needs some
+// testing.
+#define MIXER_DOUBLE_BUFFERING 1
+#endif
+
+class SdlMixerImpl : public Audio::MixerImpl {
+public:
+
+	SdlMixerImpl(OSystem *system);
+	~SdlMixerImpl();
+
+protected:
+	SDL_AudioSpec _obtainedRate;
+
+	static void mixSdlCallback(void *s, byte *samples, int len);
+
+#ifdef MIXER_DOUBLE_BUFFERING
+	SDL_mutex *_soundMutex;
+	SDL_cond *_soundCond;
+	SDL_Thread *_soundThread;
+	bool _soundThreadIsRunning;
+	bool _soundThreadShouldQuit;
+
+	byte _activeSoundBuf;
+	uint _soundBufSize;
+	byte *_soundBuffers[2];
+
+	void mixerProducerThread();
+	static int SDLCALL mixerProducerThreadEntry(void *arg);
+	void initThreadedMixer(uint bufSize);
+	void deinitThreadedMixer();
+
+public:
+	SDL_mutex *getSoundMutex() { return _soundMutex; }
+	SDL_cond *getSoundCond() { return _soundCond; }
+	uint getSoundBufSize() { return _soundBufSize; }
+	byte *getActiveSoundBuf() { return _soundBuffers[_activeSoundBuf]; }
+#endif
+};
+
+#endif