编译ffmpeg for ios

 http://blog.csdn.net/tsingien/article/details/6457246

编译ffmpeg for ios

1. 下载:
git clone git://github.com/lajos/iFrameExtractor.git

2. 编辑:
build_armv6和build_armv7,修改./configure后面的参数,主要是SDK版本.我的是4.3,修改为:
./configure --disable-doc --disable-ffmpeg --disable-ffplay --disable-ffserver --enable-cross-compile --arch=arm --target-os=darwin --cc=/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/gcc --as='gas-preprocessor/gas-preprocessor.pl /Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/gcc' --sysroot=/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS4.3.sdk --cpu=arm1176jzf-s --extra-cflags='-arch armv6' --extra-ldflags='-arch armv6'

3. 编译:
出错,提示:

/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/gcc is unable to create an executable file.
C compiler test failed.

查看config.err文件,最后提示:

ld: file not found: /usr/lib/system/libcache.dylib for architecture armv7

collect2: ld returned 1 exit status

4. 重新修改configure参数为:

./configure --disable-doc --disable-ffmpeg --disable-ffplay --disable-ffserver --enable-cross-compile --arch=arm --target-os=darwin --cc=/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/gcc --as='gas-preprocessor/gas-preprocessor.pl /Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/gcc' --sysroot=/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS4.3.sdk --cpu=cortex-a8 --extra-cflags='-arch armv7' --extra-ldflags='-arch armv7 -isysroot /Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS4.3.sdk' --enable-pic

5. 编译:

build_armv7

最后生成静态库,在lib目录和armv7目录.

6.用xcode(我的是4.0版本)打开iFrameExtractor.xcodeproj,现在编译会出错,需要修改几个地方:

左边选中工程,中间选中target,右面选中Build settings,在Architectures选项卡里面选择Architetures为Optimized(armv7),Base SDK为Latest iOS(iOS 4.3) Valid Architectures填写armv7.

编译目标选择iOS Device,当然,如果有连接电脑的设备,可以选择设备.

编译,提示:

Undefined symbols for architecture armv7:

  "_BZ2_bzDecompressInit", referenced from:

      _matroska_decode_buffer in libavformat.a(matroskadec.o)

  "_BZ2_bzDecompressEnd", referenced from:

      _matroska_decode_buffer in libavformat.a(matroskadec.o)

  "_BZ2_bzDecompress", referenced from:

      _matroska_decode_buffer in libavformat.a(matroskadec.o)

添加库libbz2.1.0.dylib,再次编译,OK通过.

7. 修改了ffmpeg版本到最新版(0.7),编译的时候需要把common.mak复制到新版本目录.
编译的时候遇到错误:
ERROR: .endm without .macro at /usr/local/bin/gas-preprocessor.pl line 83, line 55
用老版本的libavcodec/arm/asm.S和libavcoec/arm/dsputil_arm.S覆盖新版本(实际上我怀疑只覆盖asm.S即可),重新编译即可.