使用 NDK r9 编译ffmpeg

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1. 环境 ubuntu 我的是13.10  ndk r9 64位

2. 下载ffmpeg http://www.ffmpeg.org/download.html  找到 

FFmpeg 2.1.3 "Fourier"

2.1.3 was released on 2014-01-15. It is the latest stable FFmpeg release from the 2.1 release branch, which was cut from master on 2013-10-28. Amongst lots of other changes, it includes all changes from ffmpeg-mt, libav master of 2013-10-27, libav 9 as of 2013-10-27.

It includes the following library versions:

  libavutil      52. 48.101
  libavcodec     55. 39.101
  libavformat    55. 19.104
  libavdevice    55.  5.100
  libavfilter     3. 90.100
  libswscale      2.  5.101
  libswresample   0. 17.104
  libpostproc    52.  3.100

Download bzip2 tarball  下载

下载之后 解压到 $NDK/sources   文件夹下面，这是因为编译快捷以及方便使用

3.  找到 ffmpeg-xxx/configure 找到如下几行：

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)'

 上面几行会导致libavcodec.so. (e.g. libavcodec.so.55),不会被android承认 ，修改为;

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. 复制下面的代码到文本中 并命名为 build_android.sh，注意这个文件应该保存到 ffmpeg-xxx/configure 同一个文件夹下

#!/bin/bash
NDK=$HOME/Desktop/adt/android-ndk-r9
SYSROOT=$NDK/platforms/android-9/arch-arm/
TOOLCHAIN=$NDK/toolchains/arm-linux-androideabi-4.8/prebuilt/linux-x86_64
function build_one
{
./configure \
    --prefix=$PREFIX \
    --enable-shared \
    --disable-static \
    --disable-doc \
    --disable-ffmpeg \
    --disable-ffplay \
    --disable-ffprobe \
    --disable-ffserver \
    --disable-avdevice \
    --disable-doc \
    --disable-symver \
    --cross-prefix=$TOOLCHAIN/bin/arm-linux-androideabi- \
    --target-os=linux \
    --arch=arm \
    --enable-cross-compile \
    --sysroot=$SYSROOT \
    --extra-cflags="-Os -fpic $ADDI_CFLAGS" \
    --extra-ldflags="$ADDI_LDFLAGS" \
    $ADDITIONAL_CONFIGURE_FLAG
make clean
make
make install
}
CPU=arm
PREFIX=$(pwd)/android/$CPU 
ADDI_CFLAGS="-marm"
build_one

 注意修改 NDK=$HOME/Desktop/adt/android-ndk-r9 这行  

5. 执行 

sudo chmod +x build_android.sh

./build_android.sh

 6.输出  $NDK/sources/ffmpeg-xxx/android,  arm/lib 和arm/include 

注意 arm/lib包含了两个 library files (e.g.: libavcodec-55.so) 和 symbolic links (e.g.: libavcodec.so) 我们需要删掉 symbolic links .

7. 让ffmpeg Libraries用在我们的工程下

为了使ffmpeg libraries 可以作为 reusable modules, 需要添加一个文件 $NDK/sources/ffmpeg-xxx/android/arm/Android.mk 使用如下内容,

include $(CLEAR_VARS)
LOCAL_MODULE:= libavcodec
LOCAL_SRC_FILES:= lib/libavcodec-55.so
LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/include
include $(PREBUILT_SHARED_LIBRARY)
 
include $(CLEAR_VARS)
LOCAL_MODULE:= libavformat
LOCAL_SRC_FILES:= lib/libavformat-55.so
LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/include
include $(PREBUILT_SHARED_LIBRARY)
 
include $(CLEAR_VARS)
LOCAL_MODULE:= libswscale
LOCAL_SRC_FILES:= lib/libswscale-2.so
LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/include
include $(PREBUILT_SHARED_LIBRARY)
 
include $(CLEAR_VARS)
LOCAL_MODULE:= libavutil
LOCAL_SRC_FILES:= lib/libavutil-52.so
LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/include
include $(PREBUILT_SHARED_LIBRARY)
 
include $(CLEAR_VARS)
LOCAL_MODULE:= libavfilter
LOCAL_SRC_FILES:= lib/libavfilter-3.so
LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/include
include $(PREBUILT_SHARED_LIBRARY)
 
include $(CLEAR_VARS)
LOCAL_MODULE:= libwsresample
LOCAL_SRC_FILES:= lib/libswresample-0.so
LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/include
include $(PREBUILT_SHARED_LIBRARY)

 这就是为什么我们把源码放在source文件夹下，ndk会自动寻找

8.使用

 使用 libraries在Android project’s jni/Android.mk file,

LOCAL_PATH := $(call my-dir)
 
include $(CLEAR_VARS)
 
LOCAL_MODULE    := tutorial03
LOCAL_SRC_FILES := tutorial03.c
LOCAL_LDLIBS := -llog -ljnigraphics -lz -landroid
LOCAL_SHARED_LIBRARIES := libavformat libavcodec libswscale libavutil
 
include $(BUILD_SHARED_LIBRARY)
$(call import-module,ffmpeg-2.0.1/android/arm)

 这里你就会发现 我们用到了source中调用了 import-module 使用相对路径去调用。