implement new audio engine

CMakeLists.txt

@@ -4,10 +4,9 @@ project(SubWave LANGUAGES CXX)
 set(CMAKE_CXX_STANDARD 20)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 
-# ── Find Qt6 ─────────────────────────────────────────────────────────────────
 find_package(Qt6 REQUIRED COMPONENTS Widgets Multimedia OpenGL OpenGLWidgets)
 
-# ── Find FFmpeg via pkg-config ───────────────────────────────────────────────
+# require ffmpeg
 find_package(PkgConfig REQUIRED)
 pkg_check_modules(FFMPEG REQUIRED IMPORTED_TARGET
     libavformat
@@ -15,17 +14,21 @@ pkg_check_modules(FFMPEG REQUIRED IMPORTED_TARGET
     libavutil
     libswresample
 )
+# require fftw (fourier transform)
+pkg_check_modules(FFTW REQUIRED IMPORTED_TARGET fftw3)
 
-# Auto-generate MOC, and now also RCC for resource files
 set(CMAKE_AUTOMOC ON)
 set(CMAKE_AUTORCC ON)
 
-# ── Sources ──────────────────────────────────────────────────────────────────
+# source files
 set(SOURCES
     src/main.cpp
     src/MetadataReader.cpp
     src/Config.cpp
-    src/AudioEngine.cpp
+    src/engine/AudioEngine.cpp
+    src/engine/FFmpegDecoder.cpp
+    src/engine/EqProcessor.cpp
+    src/engine/SpectrumAnalyzer.cpp
     src/MusicLibrary.cpp
     src/CoverArtWidget.cpp
     src/SpectrogramWidget.cpp
@@ -40,7 +43,7 @@ set(HEADERS
     src/Track.h
     src/MetadataReader.h
     src/Config.h
-    src/AudioEngine.h
+    src/engine/AudioEngine.h
     src/MusicLibrary.h
     src/CoverArtWidget.h
     src/SpectrogramWidget.h
@@ -51,19 +54,24 @@ set(HEADERS
     src/MainWindow.h
 )
 
-set(RESOURCES src/shaders.qrc)
+set(RESOURCES 
+    src/shaders.qrc
+    src/application.qrc
+)
 
 add_executable(SubWave ${SOURCES} ${HEADERS} ${RESOURCES})
 
+target_include_directories(SubWave PRIVATE src src/engine)
+
 target_link_libraries(SubWave PRIVATE
     Qt6::Widgets
     Qt6::Multimedia
     Qt6::OpenGL
     Qt6::OpenGLWidgets
     PkgConfig::FFMPEG
+    PkgConfig::FFTW
 )
 
-# ── Copy FFmpeg shared libs next to the binary on Windows ────────────────────
 if(WIN32)
     add_custom_command(TARGET SubWave POST_BUILD
         COMMAND ${CMAKE_COMMAND} -E copy_if_different