Add audio demo

demos/CMakeLists.txt

@@ -9,6 +9,9 @@ TARGET_LINK_LIBRARIES(lines SDL2pp)
 ADD_EXECUTABLE(rendertarget rendertarget.cc)
 TARGET_LINK_LIBRARIES(rendertarget SDL2pp)
 
+ADD_EXECUTABLE(audio_sine audio_sine.cc)
+TARGET_LINK_LIBRARIES(audio_sine SDL2pp)
+
 IF(SDL2PP_WITH_IMAGE)
 	ADD_EXECUTABLE(image image.cc)
 	TARGET_LINK_LIBRARIES(image SDL2pp)

demos/audio_sine.cc

@@ -0,0 +1,67 @@
+/*
+  libSDL2pp - C++ wrapper for libSDL2
+  Copyright (C) 2013-2014 Dmitry Marakasov <amdmi3@amdmi3.ru>
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+  2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+  3. This notice may not be removed or altered from any source distribution.
+*/
+
+#include <iostream>
+
+#include <SDL2/SDL.h>
+
+#include <SDL2pp/SDL2pp.hh>
+
+using namespace SDL2pp;
+
+int Run() {
+	SDL sdl(SDL_INIT_AUDIO);
+
+	const int samplerate = 48000;
+	float frequency = 2093.00f; // C7 tone
+	int64_t nsample = 0;
+
+	// Setup audio device, and provide callback which plays sine wave with specified frequency
+	AudioSpec spec(samplerate, AUDIO_S16SYS, 1, 4096, [&nsample, frequency, samplerate](Uint8* stream, int len) {
+				// fill provided buffer with sine wave
+				for (Uint8* ptr = stream; ptr < stream + len; ptr += 2)
+					*(Uint16*)ptr = (Uint16)(32766.0f * sin(nsample++ / (float)samplerate * frequency));
+			}
+		);
+
+	// Open audio device
+	AudioDevice dev("", 0, spec);
+
+	// Sound plays after this call
+	dev.Pause(false);
+
+	// Play for 1 second, after which everything is stopped and closed
+	SDL_Delay(1000);
+
+	return 0;
+}
+
+int main() {
+	try {
+		return Run();
+	} catch (Exception& e) {
+		std::cerr << "Error: " << e.what() << " (" << e.GetSDLError() << ")" << std::endl;
+	} catch (std::exception& e) {
+		std::cerr << "Error: " << e.what() << std::endl;
+	}
+
+	return -1;
+}