最近需要用到ffmpeg开发视频相关。在网上找了些编译资源，自己摸索着，总算编译ok了。

因此，记录下苦逼的编译过程，已祭奠我为之逝去的青春。

1、准备工作

首先，到ffmpeg官网下载最新到代码。

然后，https://github.com/lajos/iFrameExtractor 下载这个示例程序。并将里面的 gas-preprocessor.pl 拷贝到 /usr/local/bin 文件夹。

2、编译

首先，附上编译原文：

Build steps

• Download the code using

git clone git://github.com/PinkyJie/iFrameExtractor.git

• Download the latest ffmpeg (0.11.1 tested) using

git clone git://source.ffmpeg.org/ffmpeg.git

• Put the ffmpeg source code into the folder ffmpeg

• Copy the perl script gas-preprocessor.pl into /usr/local/bin folder

• Change directory to your ffmpeg folder, select your target platform and follow the scripts below

Platforms

• armv7 (for iPhone 3GS and devices after 3GS)

configure

./configure \

--cc=/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/gcc \

--as=‘/usr/local/bin/gas-preprocessor.pl /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/gcc‘ \

--sysroot=/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS5.1.sdk \

--target-os=darwin \

--arch=arm \

--cpu=cortex-a8 \

--extra-cflags=‘-arch armv7‘ \

--extra-ldflags=‘-arch armv7 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS5.1.sdk‘ \

--prefix=compiled/armv7 \

--enable-cross-compile \

--enable-nonfree \

--enable-gpl \

--disable-armv5te \

--disable-swscale-alpha \

--disable-doc \

--disable-ffmpeg \

--disable-ffplay \

--disable-ffprobe \

--disable-ffserver \

--disable-asm \

--disable-debug

make

make clean

make && make install

• armv6 (for devices before 3GS)

configure

./configure \

--cc=/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/gcc \

--as=‘/usr/local/bin/gas-preprocessor.pl /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/gcc‘ \

--sysroot=/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS5.1.sdk \

--target-os=darwin \

--arch=arm \

--cpu=arm1176jzf-s \

--extra-cflags=‘-arch armv6‘ \

--extra-ldflags=‘-arch armv6 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS5.1.sdk‘ \

--prefix=compiled/armv6 \

--enable-cross-compile \

--enable-nonfree \

--enable-gpl \

--disable-armv5te \

--disable-swscale-alpha \

--disable-doc \

--disable-ffmpeg \

--disable-ffplay \

--disable-ffprobe \

--disable-ffserver \

--disable-asm \

--disable-debug

make

make clean

make && make install

• i386 (for simulator)

configure

./configure \

--cc=/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin/gcc \

--as=‘/usr/local/bin/gas-preprocessor.pl /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin/gcc‘ \

--sysroot=/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator5.1.sdk \

--target-os=darwin \

--arch=i386 \

--cpu=i386 \

--extra-cflags=‘-arch i386‘ \

--extra-ldflags=‘-arch i386 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator5.1.sdk‘ \

--prefix=compiled/i386 \

--enable-cross-compile \

--enable-nonfree \

--enable-gpl \

--disable-armv5te \

--disable-swscale-alpha \

--disable-doc \

--disable-ffmpeg \

--disable-ffplay \

--disable-ffprobe \

--disable-ffserver \

--disable-asm \

--disable-debug

make

make clean

make && make install

• universal (using one *.a files for all platforms)

mkdir -p ./compiled/fat/lib

lipo -output ./compiled/fat/lib/libavcodec.a -create \

-arch armv6 ./compiled/armv6/lib/libavcodec.a \

-arch armv7 ./compiled/armv7/lib/libavcodec.a \

-arch i386 ./compiled/i386/lib/libavcodec.a

lipo -output ./compiled/fat/lib/libavdevice.a -create \

-arch armv6 ./compiled/armv6/lib/libavdevice.a \

-arch armv7 ./compiled/armv7/lib/libavdevice.a \

-arch i386 ./compiled/i386/lib/libavdevice.a

lipo -output ./compiled/fat/lib/libavformat.a -create \

-arch armv6 ./compiled/armv6/lib/libavformat.a \

-arch armv7 ./compiled/armv7/lib/libavformat.a \

-arch i386 ./compiled/i386/lib/libavformat.a

lipo -output ./compiled/fat/lib/libavutil.a -create \

-arch armv6 ./compiled/armv6/lib/libavutil.a \

-arch armv7 ./compiled/armv7/lib/libavutil.a \

-arch i386 ./compiled/i386/lib/libavutil.a

lipo -output ./compiled/fat/lib/libswresample.a -create \

-arch armv6 ./compiled/armv6/lib/libswresample.a \

-arch armv7 ./compiled/armv7/lib/libswresample.a \

-arch i386 ./compiled/i386/lib/libswresample.a

lipo -output ./compiled/fat/lib/libpostproc.a -create \

-arch armv6 ./compiled/armv6/lib/libpostproc.a \

-arch armv7 ./compiled/armv7/lib/libpostproc.a \

-arch i386 ./compiled/i386/lib/libpostproc.a

lipo -output ./compiled/fat/lib/libswscale.a -create \

-arch armv6 ./compiled/armv6/lib/libswscale.a \

-arch armv7 ./compiled/armv7/lib/libswscale.a \

-arch i386 ./compiled/i386/lib/libswscale.a

lipo -output ./compiled/fat/lib/libavfilter.a -create \

-arch armv6 ./compiled/armv6/lib/libavfilter.a \

-arch armv7 ./compiled/armv7/lib/libavfilter.a \

-arch i386 ./compiled/i386/lib/libavfilter.a

The complied static libraries (*.a) lie in theffmpeg/compiled folder.

我想编译armv7。

然后，发现在xcode6下，上述/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/gcc

路径下根本没有gcc，于是找啊找，??在 

/Applications/Xcode.app/Contents/Developer/usr/bin/gcc

找到了gcc，行啊，试试吧！

编译OK，顺利生成了。a文件。

3、将库拷贝到示例程序中，编译，出错。提示xxxxx undefined symbols for armv7

好吧，又苦苦百度了一遍，度娘没搭理我啊。

突然发现，生成的库文件还有个pkgconfig目录，里面找到那个提示文件libavcodec相关的libavcodec.pc文件，打开一看，没怎么看懂，里面有一行说：

Libs: -L${libdir}  -lavcodec -framework CoreVideo -framework Foundation -framework AVFoundation -framework CoreMedia -liconv -lm -lbz2 -lz -pthread

于是，我就在xcode的BuildSettings里面的other link flags里面加入了 －liconv，1??竟然好使！！！

4、我靠，就先这么着吧。

还望过路的大神们，指教指教。

macOS10.9+xcode6编译ffmpeg2.4.2 for ios