Static ffmpeg build for Linux

Previously the system version of ffmpeg was linked dynamically by accident

Author: MGraefe

CMakeLists.txt

@@ -34,16 +34,15 @@ else()
 endif()
 
 
-set(ffmpegLibHint ${defFFmpegLibHint} CACHE PATH "directory with static ffmpeg libs")
+set(ffmpegLibHint "${CMAKE_CURRENT_SOURCE_DIR}/${defFFmpegLibHint}" CACHE PATH "directory with static ffmpeg libs")
 set(libSuffix ${defLibSuffix} CACHE STRING "output library suffix")
 set(pluginDir ${defPluginDir} CACHE PATH "TS3 plugin directory (for file copy)")
 
-
-find_path(ffmpegIncludeDir libavcodec/avcodec.h HINTS ${ffmpegIncHint})
-find_library(avcodec avcodec HINTS ${ffmpegLibHint})
-find_library(avformat avformat HINTS ${ffmpegLibHint})
-find_library(avutil avutil HINTS ${ffmpegLibHint})
-find_library(swresample swresample HINTS ${ffmpegLibHint})
+find_path(ffmpegIncludeDir libavcodec/avcodec.h PATHS ${ffmpegIncHint} NO_DEFAULT_PATH)
+find_library(avcodec avcodec PATHS ${ffmpegLibHint} NO_DEFAULT_PATH)
+find_library(avformat avformat PATHS ${ffmpegLibHint} NO_DEFAULT_PATH)
+find_library(avutil avutil PATHS ${ffmpegLibHint} NO_DEFAULT_PATH)
+find_library(swresample swresample PATHS ${ffmpegLibHint} NO_DEFAULT_PATH)
 
 find_package(Qt5 COMPONENTS Core Widgets Gui Network REQUIRED)
 
@@ -55,6 +54,9 @@ set(CMAKE_AUTORCC ON)
 # Find includes in corresponding build directories
 set(CMAKE_INCLUDE_CURRENT_DIR ON)
 
+# Turn fPIC on
+set(CMAKE_POSITION_INDEPENDENT_CODE ON)
+
 # version advance script (generates version.h file)
 add_custom_command(
 	OUTPUT "${CMAKE_CURRENT_SOURCE_DIR}/src/version/version.h"
@@ -67,27 +69,40 @@ set_property(SOURCE "src/version/version.h" PROPERTY SKIP_AUTOGEN ON)
 
 # actual library definition
 add_library(rp_soundboard SHARED ${sources} "src/version/version.h")
-target_link_libraries(rp_soundboard
-	Qt5::Core Qt5::Widgets Qt5::Gui Qt5::Network
-	${avcodec} ${avformat} ${avutil} ${swresample}
-)
+target_link_libraries(rp_soundboard Qt5::Core Qt5::Widgets Qt5::Gui Qt5::Network)
+if (WIN32)
+	# only link this way on Windows. Linux requires VERY special linker commands, see below
+	target_link_libraries(rp_soundboard ${avcodec} ${avformat} ${avutil} ${swresample})
+endif()
+
 target_include_directories(rp_soundboard PUBLIC "pluginsdk/include" ${ffmpegIncludeDir})
 set_target_properties(rp_soundboard PROPERTIES
 	SUFFIX ${libSuffix}
 	RUNTIME_OUTPUT_DIRECTORY_DEBUG debug
 	RUNTIME_OUTPUT_DIRECTORY_RELEASE release
 )
 
+# Special platform dependent compile options
 if (MSVC)
 	target_sources(rp_soundboard PRIVATE "src/windows/resource.h" "src/windows/Resource.rc")
 	target_link_libraries(rp_soundboard wsock32 ws2_32 secur32) # some windows stuff
 	target_compile_options(rp_soundboard PRIVATE /MP) # multiprocessor compiling
-elseif(APPLE)
-	target_compile_definitions(rp_soundboard PRIVATE "MACOS")
 else()
-	target_compile_definitions(rp_soundboard PRIVATE "LINUX")
+	if(APPLE)
+		target_compile_definitions(rp_soundboard PRIVATE "MACOS")
+	else()
+		target_compile_definitions(rp_soundboard PRIVATE "LINUX")
+	endif()
+	# Compile options that are required to NOT get the "recompile with -fPIC"
+	# error when linking the ffmpeg libs. Took me many hours to find this out...
+	set_target_properties(rp_soundboard PROPERTIES LINK_FLAGS
+		"-Wl,-Bsymbolic -Wl,--whole-archive \
+		${avcodec} ${avformat} ${avutil} ${swresample} \
+		-Wl,--no-whole-archive"
+	)
 endif()
 
+
 # copy to teamspeak dir command stuff
 set(COPY_DLL_TO_TEAMSPEAK_DIR TRUE CACHE BOOL "Copy the soundboard DLL to teamspeaks directory")
 if (COPY_DLL_TO_TEAMSPEAK_DIR)

ffmpeg/build-scripts/build_ffmpeg.sh

@@ -30,6 +30,7 @@ fi
 echo "Machine =" $machine $arch
 
 opts="\
+--enable-pic \
 --disable-programs \
 --disable-doc \
 --disable-avdevice \

ffmpeg/build-scripts/copy_binaries.sh

@@ -4,27 +4,36 @@
 
 os="$(uname -s)"
 case "$os" in 
-	Linux*)	prefix="lib_lin"
-		postfix="a" ;;
-	Darwin*) prefix="lib_mac" 
-		postfix="a" ;;
-	*) prefix="lib_win" 
-	   postfix="lib" ;;
+	Linux*)
+		prefix="lib_lin"
+		postfix="a"
+		infix="lib"
+		;;
+	Darwin*)
+		prefix="lib_mac"
+		postfix="a"
+		infix="lib"
+		;;
+	*)
+		prefix="lib_win"
+		infix=""
+		postfix="lib"
+		;;
 esac
 
 pushd ..
 
 mkdir -p "${prefix}_x64"
 mkdir -p "${prefix}_x86"
 
-cp ffmpeg/x64/lib/libavcodec.a ${prefix}_x64/avcodec.$postfix
-cp ffmpeg/x64/lib/libavformat.a ${prefix}_x64/avformat.$postfix
-cp ffmpeg/x64/lib/libavutil.a ${prefix}_x64/avutil.$postfix
-cp ffmpeg/x64/lib/libswresample.a ${prefix}_x64/swresample.$postfix
+cp ffmpeg/x64/lib/libavcodec.a ${prefix}_x64/${infix}avcodec.$postfix
+cp ffmpeg/x64/lib/libavformat.a ${prefix}_x64/${infix}avformat.$postfix
+cp ffmpeg/x64/lib/libavutil.a ${prefix}_x64/${infix}avutil.$postfix
+cp ffmpeg/x64/lib/libswresample.a ${prefix}_x64/${infix}swresample.$postfix
 cp -R ffmpeg/x64/include ${prefix}_x64/include
 
-cp ffmpeg/x86/lib/libavcodec.a ${prefix}_x86/avcodec.$postfix
-cp ffmpeg/x86/lib/libavformat.a ${prefix}_x86/avformat.$postfix
-cp ffmpeg/x86/lib/libavutil.a ${prefix}_x86/avutil.$postfix
-cp ffmpeg/x86/lib/libswresample.a ${prefix}_x86/swresample.$postfix
+cp ffmpeg/x86/lib/libavcodec.a ${prefix}_x86/${infix}avcodec.$postfix
+cp ffmpeg/x86/lib/libavformat.a ${prefix}_x86/${infix}avformat.$postfix
+cp ffmpeg/x86/lib/libavutil.a ${prefix}_x86/${infix}avutil.$postfix
+cp ffmpeg/x86/lib/libswresample.a ${prefix}_x86/${infix}swresample.$postfix
 cp -R ffmpeg/x86/include ${prefix}_x86/include