mac下编译Android ffmpeg4.1 + x264

主要参考文章：
编译针对于Android平台的ffmpeg 4.1版本(最新版)
x264编译问题处理

一、编译x264
1）x264 源码
2）脚本

#!/bin/sh
NDK=/Users/johnwu/Documents/android/android-ndk-r17c
API=21 #最低支持Android版本
HOST_PLATFORM=darwin-x86_64
cd x264
function build_one { 
  OUTPUT=$(pwd)/"android"/"$CPU"
  echo "开始编译"
  echo "CPU = $CPU "
  echo "OUTPUT = $OUTPUT "
  echo "CROSS_PREFIX = $CROSS_PREFIX "
  echo "SYSROOT = $SYSROOT "
  echo "EXTRA_CFLAGS = $EXTRA_CFLAGS "
  echo "EXTRA_LDFLAGS = $EXTRA_LDFLAGS "
  ./configure \
  --prefix=$OUTPUT \
  --cross-prefix=$CROSS_PREFIX \
  --sysroot=$SYSROOT \
  --host=$HOST \
  --disable-asm \
  --disable-shared \
  --enable-static \
  --disable-opencl \
  --enable-pic \
  --disable-cli \
  --extra-cflags="$EXTRA_CFLAGS" \
  --extra-ldflags="$EXTRA_LDFLAGS" 
   make clean 
   make -j4
   make install
   echo "编译结束"
 }
CPUS="armeabi-v7a x86"
if [ "$*" ]
then
     CPUS="$*"   #如果有输入参数 则只编译 该架构
fi
echo "编译以下 架构 $CPUS"

for CPU_TEMP in $CPUS
do
     case $CPU_TEMP in 
          "armeabi-v7a")
               CPU="armeabi-v7a"
               CROSS_PREFIX=$NDK/toolchains/arm-linux-androideabi-4.9/prebuilt/$HOST_PLATFORM/bin/arm-linux-androideabi-
               SYSROOT=$NDK/platforms/android-$API/arch-arm/
               EXTRA_CFLAGS="-D__ANDROID_API__=$API -isysroot $NDK/sysroot -I$NDK/sysroot/usr/include/arm-linux-androideabi -Os -fPIC -marm"
               EXTRA_LDFLAGS="-marm"
               HOST=arm-linux
               build_one
          ;;
          "x86")
               CPU="x86"
               CROSS_PREFIX=$NDK/toolchains/x86-4.9/prebuilt/$HOST_PLATFORM/bin/i686-linux-android-
               SYSROOT=$NDK/platforms/android-$API/arch-x86/
               EXTRA_CFLAGS="-D__ANDROID_API__=$API -isysroot $NDK/sysroot -I$NDK/sysroot/usr/include/i686-linux-android -Os -fPIC"
               EXTRA_LDFLAGS=""
               HOST=i686-linux
               build_one
          ;;
     esac
done

二、编译 ffmpeg + x264
准备材料：
1）ffmpeg版本 4.1
2）ndk版本 r17c
3）build 脚本

#!/bin/sh
NDK=/Users/johnwu/Documents/android/android-ndk-r17c
API=21 #最低支持Android版本
HOST_PLATFORM=darwin-x86_64
cd ffmpeg-4.1
function build_one { 
     OUTPUT=$(pwd)/"android"/"$CPU"
     echo "开始编译"
     echo "CPU = $CPU "
     echo "OUTPUT = $OUTPUT "
     echo "CROSS_PREFIX = $CROSS_PREFIX "
     echo "ARCH = $ARCH "
     echo "SYSROOT = $SYSROOT "
     echo "EXTRA_CFLAGS = $EXTRA_CFLAGS "
     echo "EXTRA_LDFLAGS = $EXTRA_LDFLAGS "
     ./configure \
     --prefix=$OUTPUT \
     --enable-gpl \
     --enable-debug=3 \
     --enable-libx264 \
     --enable-shared \
     --disable-asm \
     --disable-static \
     --disable-doc \
     --disable-ffmpeg \
     --disable-ffplay \
     --disable-ffprobe \
     --disable-avdevice \
     --disable-doc \
     --disable-symver \
     --cross-prefix=$CROSS_PREFIX \
     --target-os=linux \
     --arch=$ARCH \
     --enable-cross-compile \
     --sysroot=$SYSROOT \
     --extra-cflags="$EXTRA_CFLAGS" \
     --extra-ldflags="$EXTRA_LDFLAGS" \
     $ADDITIONAL_CONFIGURE_FLAG 
     make clean 
     make -j4
     make install
     echo "编译结束"
 }

# CPUS="arm64-v8a armeabi armeabi-v7a mips mips64 x86 x86_64"
# CPUS="arm64-v8a armeabi-v7a x86 x86_64" #目前高级的ndk 要求支持这几种即可
CPUS="armeabi-v7a x86"
if [ "$*" ]
then
     CPUS="$*"   #如果有输入参数 则只编译 该架构
fi
echo "编译以下 架构 $CPUS"

for CPU_TEMP in $CPUS
do
     case $CPU_TEMP in 
          "armeabi-v7a")
               CPU="armeabi-v7a"
               ARCH=armeabi-v7a
               X264_INCLUDE=/Users/johnwu/Documents/c_project/x264/x264/android/armeabi-v7a/include
               X264_LIB=/Users/johnwu/Documents/c_project/x264/x264/android/armeabi-v7a/lib
               CROSS_PREFIX=$NDK/toolchains/arm-linux-androideabi-4.9/prebuilt/$HOST_PLATFORM/bin/arm-linux-androideabi-
               SYSROOT=$NDK/platforms/android-$API/arch-arm/
               EXTRA_CFLAGS="-I$X264_INCLUDE -isysroot $NDK/sysroot -I$NDK/sysroot/usr/include/arm-linux-androideabi -Os -fpic -marm"
               EXTRA_LDFLAGS="-L$X264_LIB -marm"
               build_one
          ;;
          "x86")
               CPU="x86"
               ARCH=x86
               X264_INCLUDE=/Users/johnwu/Documents/c_project/x264/x264/android/x86/include
               X264_LIB=/Users/johnwu/Documents/c_project/x264/x264/android/x86/lib
               CROSS_PREFIX=$NDK/toolchains/x86-4.9/prebuilt/$HOST_PLATFORM/bin/i686-linux-android-
               SYSROOT=$NDK/platforms/android-$API/arch-x86/
               EXTRA_CFLAGS="-I$X264_INCLUDE -isysroot $NDK/sysroot -I$NDK/sysroot/usr/include/i686-linux-android -Os -fpic"
               EXTRA_LDFLAGS="-L$X264_LIB"
               build_one
          ;;
     esac
done

4）ffmpeg涉及的修改：

4.1 configure脚本进行修改，为了生成的动态库命名方式可以被Android平台理解,识别

SLIBNAME_WITH_MAJOR='$(SLIBNAME).$(LIBMAJOR)'
LIB_INSTALL_EXTRA_CMD='$$(RANLIB) "$(LIBDIR)/$(LIBNAME)"'
SLIB_INSTALL_NAME='$(SLIBNAME_WITH_VERSION)'
SLIB_INSTALL_LINKS='$(SLIBNAME_WITH_MAJOR) $(SLIBNAME)'

修改后:

SLIBNAME_WITH_MAJOR='$(SLIBPREF)$(FULLNAME)-$(LIBMAJOR)$(SLIBSUF)'
LIB_INSTALL_EXTRA_CMD='$$(RANLIB) "$(LIBDIR)/$(LIBNAME)"'
SLIB_INSTALL_NAME='$(SLIBNAME_WITH_MAJOR)'
SLIB_INSTALL_LINKS='$(SLIBNAME)'

4.2 遇到的坑 按参考的文章，外加下面的坑
添加 --disable-asm 修复 Android 6.0以上遇到的问题：ffmpeg text relocations

注意：在编译ffmpeg + 264 的时候遇到 ERROR: libx264 not found
得去看 config.log, FFmpeg 项目的 config.log 中有提示： x264 undefined reference to 'stderr'
出现这个错误是因为 x264 编译失败了，但 libx264.so 还是生成了，并且看起来就像是真的编译成功了一样。参考x264编译问题处理