编译lame静态库

1. 下载所需要的lame版本
2. 写自动化脚本

#!/bin/sh

CONFIGURE_FLAGS="--disable-shared --disable-frontend"

ARCHS="arm64 armv7s x86_64 i386 armv7"

# directories
# SOURCE 解压后lame的本地地址
SOURCE="修改为自己的lame地址"
FAT="fat-lame"

# SCRATCH 解压后lame的本地地址
SCRATCH="修改为自己的lame地址"
# must be an absolute path
THIN=`pwd`/"thin-lame"

COMPILE="y"
LIPO="y"

if [ "$*" ]
then
	if [ "$*" = "lipo" ]
	then
		# skip compile
		COMPILE=
	else
		ARCHS="$*"
		if [ $# -eq 1 ]
		then
			# skip lipo
			LIPO=
		fi
	fi
fi

if [ "$COMPILE" ]
then
	CWD=`pwd`
	for ARCH in $ARCHS
	do
		echo "building $ARCH..."
		mkdir -p "$SCRATCH/$ARCH"
		cd "$SCRATCH/$ARCH"

		if [ "$ARCH" = "i386" -o "$ARCH" = "x86_64" ]
		then
		    PLATFORM="iPhoneSimulator"
		    if [ "$ARCH" = "x86_64" ]
		    then
		    	SIMULATOR="-mios-simulator-version-min=7.0"
                        HOST=x86_64-apple-darwin
		    else
		    	SIMULATOR="-mios-simulator-version-min=5.0"
                        HOST=i386-apple-darwin
		    fi
		else
		    PLATFORM="iPhoneOS"
		    SIMULATOR=
                    HOST=arm-apple-darwin
		fi

		XCRUN_SDK=`echo $PLATFORM | tr '[:upper:]' '[:lower:]'`
		CC="xcrun -sdk $XCRUN_SDK clang -arch $ARCH"
		#AS="$CWD/$SOURCE/extras/gas-preprocessor.pl $CC"
		CFLAGS="-arch $ARCH $SIMULATOR"
		if ! xcodebuild -version | grep "Xcode [1-6]."
		then
			CFLAGS="$CFLAGS -fembed-bitcode"
		fi
		CXXFLAGS="$CFLAGS"
		LDFLAGS="$CFLAGS"

		CC=$CC $CWD/$SOURCE/configure 
		    $CONFIGURE_FLAGS 
                    --host=$HOST 
		    --prefix="$THIN/$ARCH" 
                    CC="$CC" CFLAGS="$CFLAGS" LDFLAGS="$LDFLAGS"

		make -j3 install
		cd $CWD
	done
fi

if [ "$LIPO" ]
then
	echo "building fat binaries..."
	mkdir -p $FAT/lib
	set - $ARCHS
	CWD=`pwd`
	cd $THIN/$1/lib
	for LIB in *.a
	do
		cd $CWD
		lipo -create `find $THIN -name $LIB` -output $FAT/lib/$LIB
	done

	cd $CWD
	cp -rf $THIN/$1/include $FAT
fi

3. 编译文件

# 进入编译脚本的文件夹
cd /xxx/lame
# -rwxr-xr-x 拥有者有读、写、执行权限；而属组用户和其他用户只有读、执行权限。
chmod 755 ./build-lame.sh
# 执行脚本
sudo sh ./build-lame.sh

4. 编译完成, 生成fat-lame目录和thin-lame目录，分别存放合并所有指令集的静态库，以及各指令集的静态库.
5. 查看.a文件的指令集

lipo -info libmp3lame.a

6. 验证是否支持bitcode

# 解压抽取lame.o
ar -x libmp3lame.a
# 检查是否支持bitcode若输出sectname __bitcode则支持bitcode 
otool -l lame.o | grep bitcode