用Android NDK编译FFmpeg错误解决

转载：http://abitno.me/compile-ffmpeg-android-ndk

编译出来只有15k,后来借鉴这篇文章：http://www.cnblogs.com/shaobin0604/archive/2011/08/05/2128619.html成功,期间有一个错误在Android.mk中遗忘了一个依赖文件rtpdec_gxx忘了，根据错误提示解决。

首先创建一个标准的Android项目vPlayer

android create project -n vPlayer -t 8 -p vPlayer -k me.abitno.vplayer -a PlayerView -t android-16

然后在vPlayer目录里

mkdir jni && cd jni
wget http://ffmpeg.org/releases/ffmpeg-0.6.tar.bz2
tar xf ffmpeg-0.6.tar.bz2 && mv ffmpeg-0.6 ffmpeg && cd ffmpeg

在ffmpeg下新建一个config.sh，内容如下，注意把PREBUILT和PLATFORM设置正确。另外里面有些参数你也可以自行调整，我主要是为了配置一个播放器而这样设置的。

(不同的ndk版本，PREBUILT PLATFORM armelf.x crtbegin.o crtend.o 路径不同)

#!/bin/bash

PREBUILT=/home/toddmi/SDK/android-ndk-r8b/toolchains/arm-linux-androideabi-4.4.3/prebuilt/linux-x86
PLATFORM=/home/toddmi/SDK/android-ndk-r8b/platforms/android-8/arch-arm

./configure --target-os=linux \
	--arch=arm \
	--enable-version3 \
	--enable-gpl \
	--enable-nonfree \
	--disable-stripping \
	--disable-ffmpeg \
	--disable-ffplay \
	--disable-ffserver \
	--disable-ffprobe \
	--disable-encoders \
	--disable-muxers \
	--disable-devices \
	--disable-protocols \
	--enable-protocol=file \
	--enable-avfilter \
	--disable-network \
	--disable-mpegaudio-hp \
	--disable-avdevice \
	--enable-cross-compile \
	--cc=$PREBUILT/bin/arm-linux-androideabi-gcc-4.4.3 \
	--cross-prefix=$PREBUILT/bin/arm-linux-androideabi- \
	--nm=$PREBUILT/bin/arm-linux-androideabi-nm \
	--extra-cflags="-fPIC -DANDROID" \
	--disable-asm \
	--enable-neon \
	--enable-armv5te \
	--extra-ldflags="-Wl,-T,$PREBUILT/arm-linux-androideabi/lib/ldscripts/armelf_linux_eabi.x -Wl,-rpath-link=$PLATFORM/usr/lib -L$PLATFORM/usr/lib -nostdlib $PREBUILT/lib/gcc/arm-linux-androideabi/4.4.3/crtbegin.o $PREBUILT/lib/gcc/arm-linux-androideabi/4.4.3/crtend.o -lc -lm -ldl"

运行config.sh开始configure

chmod +x config.sh
./config.sh

configure完成后，编辑刚刚生成的config.h，找到这句

#define restrict restrict

Android的GCC不支持restrict关键字，于是修改成下面这样

#define restrict

编辑libavutil/libm.h，把其中的static方法都删除。（删掉static即可）

分别修改libavcodec、libavfilter、libavformat、libavutil、libpostproc和libswscale下的Makefile，把下面两句删除

include $(SUBDIR)../subdir.mak
include $(SUBDIR)../config.mak

在ffmpeg下添加一个文件av.mk，内容如下

# LOCAL_PATH is one of libavutil, libavcodec, libavformat, or libswscale

#include $(LOCAL_PATH)/../config-$(TARGET_ARCH).mak
include $(LOCAL_PATH)/../config.mak

OBJS :=
OBJS-yes :=
MMX-OBJS-yes :=
include $(LOCAL_PATH)/Makefile

# collect objects
OBJS-$(HAVE_MMX) += $(MMX-OBJS-yes)
OBJS += $(OBJS-yes)

FFNAME := lib$(NAME)
FFLIBS := $(foreach,NAME,$(FFLIBS),lib$(NAME))
FFCFLAGS  = -DHAVE_AV_CONFIG_H -Wno-sign-compare -Wno-switch -Wno-pointer-sign
FFCFLAGS += -DTARGET_CONFIG=\"config-$(TARGET_ARCH).h\"

ALL_S_FILES := $(wildcard $(LOCAL_PATH)/$(TARGET_ARCH)/*.S)
ALL_S_FILES := $(addprefix $(TARGET_ARCH)/, $(notdir $(ALL_S_FILES)))

ifneq ($(ALL_S_FILES),)
ALL_S_OBJS := $(patsubst %.S,%.o,$(ALL_S_FILES))
C_OBJS := $(filter-out $(ALL_S_OBJS),$(OBJS))
S_OBJS := $(filter $(ALL_S_OBJS),$(OBJS))
else
C_OBJS := $(OBJS)
S_OBJS :=
endif

C_FILES := $(patsubst %.o,%.c,$(C_OBJS))
S_FILES := $(patsubst %.o,%.S,$(S_OBJS))

FFFILES := $(sort $(S_FILES)) $(sort $(C_FILES))

接下来要添加一系列的Android.mk，在jni根目录下的内容如下

include $(all-subdir-makefiles)

在ffmpeg目录下，Android.mk

LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_STATIC_LIBRARIES := libavformat libavcodec libavutil libpostproc libswscale
LOCAL_MODULE := ffmpeg
include $(BUILD_SHARED_LIBRARY)
include $(call all-makefiles-under,$(LOCAL_PATH))

libavformat/Android.mk

LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
include $(LOCAL_PATH)/../av.mk
LOCAL_SRC_FILES := $(FFFILES)
LOCAL_C_INCLUDES :=		\
	$(LOCAL_PATH)		\
	$(LOCAL_PATH)/..
LOCAL_CFLAGS += $(FFCFLAGS)
LOCAL_CFLAGS += -include "string.h" -Dipv6mr_interface=ipv6mr_ifindex
LOCAL_LDLIBS := -lz
LOCAL_STATIC_LIBRARIES := $(FFLIBS)
LOCAL_MODULE := $(FFNAME)
include $(BUILD_STATIC_LIBRARY)

libavcodec/Android.mk

LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
include $(LOCAL_PATH)/../av.mk
LOCAL_SRC_FILES := $(FFFILES)
LOCAL_C_INCLUDES :=		\
	$(LOCAL_PATH)		\
	$(LOCAL_PATH)/..
LOCAL_CFLAGS += $(FFCFLAGS)
LOCAL_LDLIBS := -lz
LOCAL_STATIC_LIBRARIES := $(FFLIBS)
LOCAL_MODULE := $(FFNAME)
include $(BUILD_STATIC_LIBRARY)

libavfilter、libavutil、libpostproc和libswscale下的Android.mk内容如下

LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
include $(LOCAL_PATH)/../av.mk
LOCAL_SRC_FILES := $(FFFILES)
LOCAL_C_INCLUDES :=		\
	$(LOCAL_PATH)		\
	$(LOCAL_PATH)/..
LOCAL_CFLAGS += $(FFCFLAGS)
LOCAL_STATIC_LIBRARIES := $(FFLIBS)
LOCAL_MODULE := $(FFNAME)
include $(BUILD_STATIC_LIBRARY)

最外层的jni/Android.mk和jni/ffmpeg/Android.mk我只是随便这样写的，你应该根据自己的需求改写。

最后运行ndk-build，经过漫长的等待就编译完成了。至于具体怎么应用可能以后会写，我变得太懒了。。。

编译时出现undefine refence “xxxxx“,问题在Amdroid.mk文件编译规则引用文件没有加全。

我已经尽最大努力写明白了，希望大家努力啊，一个全功能的解码器或者只是播放器还是很有必要的。

更新：想偷情的可以看这个在Android NDK中使用libffmpeg.so