Overhaul platform and decoder/renderer detection

app/app.pro

@@ -34,15 +34,26 @@ macx {
 
 unix:!macx {
     CONFIG += link_pkgconfig
-    PKGCONFIG += openssl sdl2 libavcodec libavdevice libavformat libavutil
+    PKGCONFIG += openssl sdl2
     LIBS += -ldl
+
+    packagesExist(libavcodec) {
+        PKGCONFIG += libavcodec libavdevice libavformat libavutil
+        CONFIG += ffmpeg
+
+        packagesExist(libva) {
+            CONFIG += libva
+        }
+    }
 }
 win32 {
     LIBS += -llibssl -llibcrypto -lSDL2 -lavcodec -lavdevice -lavformat -lavutil
+    CONFIG += ffmpeg
 }
 macx {
     LIBS += -lssl -lcrypto -lSDL2 -lavcodec.58 -lavdevice.58 -lavformat.58 -lavutil.56
     LIBS += -lobjc -framework VideoToolbox -framework AVFoundation -framework CoreVideo -framework CoreGraphics -framework CoreMedia -framework AppKit
+    CONFIG += ffmpeg
 }
 
 SOURCES += \
@@ -56,20 +67,8 @@ SOURCES += \
     streaming/input.cpp \
     streaming/session.cpp \
     streaming/audio.cpp \
-    streaming/video/ffmpeg.cpp \
     gui/computermodel.cpp \
-    gui/appmodel.cpp \
+    gui/appmodel.cpp
-    streaming/video/ffmpeg-renderers/sdl.cpp
-
-win32 {
-    SOURCES += streaming/video/ffmpeg-renderers/dxva2.cpp
-}
-macx {
-    SOURCES += streaming/video/ffmpeg-renderers/vt.mm
-}
-unix:!macx {
-    SOURCES += streaming/video/ffmpeg-renderers/vaapi.cpp
-}
 
 HEADERS += \
     utils.h \
@@ -83,19 +82,38 @@ HEADERS += \
     streaming/session.hpp \
     gui/computermodel.h \
     gui/appmodel.h \
-    streaming/video/decoder.h \
+    streaming/video/decoder.h
-    streaming/video/ffmpeg.h \
-    streaming/video/ffmpeg-renderers/renderer.h
 
+# Platform-specific renderers and decoders
+ffmpeg {
+    message(FFmpeg decoder selected)
+
+    DEFINES += HAVE_FFMPEG
+    SOURCES += \
+        streaming/video/ffmpeg.cpp \
+        streaming/video/ffmpeg-renderers/sdl.cpp
+    HEADERS += \
+        streaming/video/ffmpeg.h \
+        streaming/video/ffmpeg-renderers/renderer.h
+}
+libva {
+    message(VAAPI renderer selected)
+
+    DEFINES += HAVE_LIBVA
+    SOURCES += streaming/video/ffmpeg-renderers/vaapi.cpp
+}
 win32 {
+    message(DXVA2 renderer selected)
+
+    SOURCES += streaming/video/ffmpeg-renderers/dxva2.cpp
     HEADERS += streaming/video/ffmpeg-renderers/dxva2.h
 }
 macx {
+    message(VideoToolbox renderer selected)
+
+    SOURCES += streaming/video/ffmpeg-renderers/vt.mm
     HEADERS += streaming/video/ffmpeg-renderers/vt.h
 }
-unix {
-    HEADERS += streaming/video/ffmpeg-renderers/vaapi.h
-}
 
 RESOURCES += \
     resources.qrc \

app/streaming/audio.cpp

@@ -127,7 +127,7 @@ int Session::sdlAudioInit(int /* audioConfiguration */,
     // pending data count. Get a baseline so we
     // can exclude that data.
     s_BaselinePendingData = 0;
-#ifdef _WIN32
+#ifdef Q_OS_WIN32
     for (int i = 0; i < 100; i++) {
         s_BaselinePendingData = qMax(s_BaselinePendingData, SDL_GetQueuedAudioSize(s_AudioDevice));
         SDL_Delay(10);

app/streaming/session.cpp

@@ -82,6 +82,7 @@ bool Session::chooseDecoder(StreamingPreferences::VideoDecoderSelection vds,
                             SDL_Window* window, int videoFormat, int width, int height,
                             int frameRate, IVideoDecoder*& chosenDecoder)
 {
+#ifdef HAVE_FFMPEG
     chosenDecoder = new FFmpegVideoDecoder();
     if (chosenDecoder->initialize(vds, window, videoFormat, width, height, frameRate)) {
         SDL_LogInfo(SDL_LOG_CATEGORY_APPLICATION,
@@ -94,6 +95,7 @@ bool Session::chooseDecoder(StreamingPreferences::VideoDecoderSelection vds,
         delete chosenDecoder;
         chosenDecoder = nullptr;
     }
+#endif
 
     // If we reach this, we didn't initialize any decoders successfully
     return false;

app/streaming/video/ffmpeg.cpp

@@ -1,13 +1,15 @@
 #include <Limelight.h>
 #include "ffmpeg.h"
 
-#ifdef _WIN32
+#ifdef Q_OS_WIN32
 #include "ffmpeg-renderers/dxva2.h"
 #endif
 
-#ifdef __APPLE__
+#ifdef Q_OS_DARWIN
 #include "ffmpeg-renderers/vt.h"
-#elif defined Q_OS_UNIX
+#endif
+
+#ifdef HAVE_LIBVA
 #include "ffmpeg-renderers/vaapi.h"
 #endif
 
@@ -62,16 +64,17 @@ bool FFmpegVideoDecoder::chooseDecoder(
 
         // Look for acceleration types we support
         switch (config->device_type) {
-#ifdef _WIN32
+#ifdef Q_OS_WIN32
         case AV_HWDEVICE_TYPE_DXVA2:
             newRenderer = new DXVA2Renderer();
             break;
 #endif
-#ifdef __APPLE__
+#ifdef Q_OS_DARWIN
         case AV_HWDEVICE_TYPE_VIDEOTOOLBOX:
             newRenderer = VTRendererFactory::createRenderer();
             break;
-#elif defined Q_OS_UNIX
+#endif
+#ifdef HAVE_LIBVA
         case AV_HWDEVICE_TYPE_VAAPI:
             newRenderer = new VAAPIRenderer();
             break;