From 2c5987963033ba4164c76993e458828d6ec6b82a Mon Sep 17 00:00:00 2001
From: lisyarus <lisyarus@gmail.com>
Date: Fri, 7 Oct 2022 23:40:03 +0300
Subject: [PATCH] Support loading WAV audio

---
 libs/audio/include/psemek/audio/engine.hpp |  2 +-
 libs/audio/source/engine.cpp               | 61 +++++++++++++++++++---
 2 files changed, 56 insertions(+), 7 deletions(-)

diff --git a/libs/audio/include/psemek/audio/engine.hpp b/libs/audio/include/psemek/audio/engine.hpp
index ec4b3cf6..e955a0db 100644
--- a/libs/audio/include/psemek/audio/engine.hpp
+++ b/libs/audio/include/psemek/audio/engine.hpp
@@ -21,8 +21,8 @@ namespace psemek::audio
 		engine();
 		~engine();
 
-		track_ptr load_raw(float const * data, std::size_t sample_count, bool copy = true);
 		track_ptr load_raw(util::span<float const> data, bool copy = true);
+		track_ptr load_wav(util::span<char const> data);
 
 		channel_ptr output();
 
diff --git a/libs/audio/source/engine.cpp b/libs/audio/source/engine.cpp
index 3fc4e61d..92432275 100644
--- a/libs/audio/source/engine.cpp
+++ b/libs/audio/source/engine.cpp
@@ -3,6 +3,8 @@
 #include <psemek/sdl2/init.hpp>
 #include <psemek/log/log.hpp>
 #include <psemek/prof/profiler.hpp>
+#include <psemek/util/at_scope_exit.hpp>
+#include <psemek/util/to_string.hpp>
 
 #include <SDL2/SDL.h>
 
@@ -77,6 +79,41 @@ namespace psemek::audio
 			std::shared_ptr<track_data> data_;
 		};
 
+		std::vector<float> convert_audio(SDL_AudioSpec const & spec, std::uint8_t * samples, std::size_t length)
+		{
+			if (spec.channels > 2)
+				throw std::runtime_error(util::to_string("Can't convert audio with ", static_cast<int>(spec.channels), " channels"));
+
+			if (spec.freq != 44100)
+				throw std::runtime_error(util::to_string("Can't convert audio with frequency ", spec.freq));
+
+			if (spec.format != AUDIO_S16SYS)
+				throw std::runtime_error(util::to_string("Can't convert audio with format ", spec.format));
+
+			auto p = reinterpret_cast<std::int16_t *>(samples);
+
+			std::vector<float> result;
+
+			if (spec.channels == 1)
+			{
+				result.resize(length);
+				for (std::size_t i = 0; i < length / 2; ++i)
+				{
+					float v = (p[i] * 2.f + 1.f) / 65536.f;
+					result[2 * i + 0] = v;
+					result[2 * i + 1] = v;
+				}
+			}
+			else
+			{
+				result.resize(length / 2);
+				for (std::size_t i = 0; i < length / 2; ++i)
+					result[i] = (p[i] * 2.f + 1.f) / 65536.f;
+			}
+
+			return result;
+		}
+
 	}
 
 	struct engine::impl
@@ -154,26 +191,38 @@ namespace psemek::audio
 
 	engine::~engine() = default;
 
-	track_ptr engine::load_raw(float const * data, std::size_t sample_count, bool copy)
+	track_ptr engine::load_raw(util::span<float const> data, bool copy)
 	{
-		if ((sample_count % 2) != 0)
+		if ((data.size() % 2) != 0)
 			throw std::runtime_error("bad sample count");
 
 		auto tdata = std::make_shared<track_data>();
 		if (copy)
 		{
-			tdata->storage.assign(data, data + sample_count);
+			tdata->storage.assign(data.begin(), data.end());
 			tdata->samples = tdata->storage;
 		}
 		else
-			tdata->samples = {data, data + sample_count};
+			tdata->samples = data;
 
 		return std::make_shared<track_impl>(std::move(tdata));
 	}
 
-	track_ptr engine::load_raw(util::span<float const> data, bool copy)
+	track_ptr engine::load_wav(util::span<char const> data)
 	{
-		return load_raw(data.data(), data.size(), copy);
+		SDL_AudioSpec spec;
+		std::uint8_t * samples;
+		std::uint32_t length;
+		if (!SDL_LoadWAV_RW(SDL_RWFromConstMem(data.data(), data.size()), 1, &spec, &samples, &length))
+			sdl2::fail("SDL_LoadWAV_RW failed:");
+
+		util::at_scope_exit release_samples([samples]{ SDL_FreeWAV(samples); });
+
+		auto tdata = std::make_shared<track_data>();
+		tdata->storage = convert_audio(spec, samples, length);
+		tdata->samples = tdata->storage;
+
+		return std::make_shared<track_impl>(std::move(tdata));
 	}
 
 	channel_ptr engine::output()