___________________________编译环境__________________________________
NDK 环境：android-ndk-r13b
MinGW环境：Basic Setup下Mark了所有的项目，FFmpeg需要使用msys环境进行编译
ffmpeg ：3.2.4 下载地址
libx264：官网最新
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___________________________编译配置___________________________________
在解压的ffmpeg目录下新建一个sh文件，并填入如下内容
关键变量设置是NDK路径
#!/bin/bash
NDK=E:/android-ndk-r13b
SYSROOT=$NDK/platforms/android-19/arch-arm/
TOOLCHAIN=$NDK/toolchains/arm-linux-androideabi-4.9/prebuilt/windows-x86_64
function build_one {
./configure --prefix=$PREFIX --enable-asm --enable-neon --enable-static --enable-small --disable-shared --disable-ffmpeg --disable-ffplay --disable-ffprobe --disable-ffserver --disable-avdevice --disable-doc --disable-symver --cross-prefix=$TOOLCHAIN/bin/arm-linux-androideabi- --target-os=linux --arch=arm --cpu=armv7-a --enable-cross-compile --sysroot=$SYSROOT --extra-cflags="-fPIC -DANDROID -mfpu=neon -mfloat-abi=softfp -I$NDK/platforms/android-19/arch-arm/usr/include" --extra-ldflags="$ADDI_LDFLAGS"
make clean
make
make install
}
CPU=arm
PREFIX=$(pwd)/android/$CPU
ADDI_CFLAGS="-marm"
build_one
附带上libx264库加入进来后的编译脚本(EXTRA_LIB 指向的是 libx264编译后生成目录，包括头文件[include]和静态库[lib]文件夹)：
#!/bin/bash
NDK=E:/android-ndk-r13b
SYSROOT=$NDK/platforms/android-19/arch-arm/
TOOLCHAIN=$NDK/toolchains/arm-linux-androideabi-4.9/prebuilt/windows-x86_64
EXTRA_LIB=E:/FFmpeg/android-lib
function build_one {
./configure --prefix=$PREFIX --enable-asm --enable-neon --enable-static --enable-small --enable-libx264 --enable-gpl --enable-encoder=libx264 --disable-shared --disable-doc --disable-ffmpeg --disable-ffplay --disable-ffprobe --disable-ffserver --disable-avdevice --disable-symver --cross-prefix=$TOOLCHAIN/bin/arm-linux-androideabi- --target-os=linux --arch=arm --cpu=armv7-a --enable-cross-compile --sysroot=$SYSROOT --extra-cflags="-I$EXTRA_LIB/include -fPIC -DANDROID -mfpu=neon -mfloat-abi=softfp -I$NDK/platforms/android-19/arch-arm/usr/include" --extra-ldflags="-L$EXTRA_LIB/lib -lx264 $ADDI_LDFLAGS"
make clean
make
make install
}
CPU=arm
PREFIX=$(pwd)/android/x264_lib/$CPU
ADDI_CFLAGS="-marm"
build_one
编译好后，Eclipse新建工程，添加C++库支持，编写java jni接口，在bin下的classes目录下，使用javah可以生成头文件。
附上主要实现代码，以及两个编译mk文件写法:
Android.mk
LOCAL_PATH := $(call my-dir) # prepare libX include $(CLEAR_VARS) TARGET_ARCH_ABI := armeabi-v7a LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/include LOCAL_MODULE := avcodec LOCAL_SRC_FILES := libavcodec.a include $(PREBUILT_STATIC_LIBRARY) # prepare libX include $(CLEAR_VARS) TARGET_ARCH_ABI := armeabi-v7a LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/include LOCAL_MODULE := avfilter LOCAL_SRC_FILES := libavfilter.a include $(PREBUILT_STATIC_LIBRARY) # prepare libX include $(CLEAR_VARS) TARGET_ARCH_ABI := armeabi-v7a LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/include LOCAL_MODULE := avformat LOCAL_SRC_FILES := libavformat.a include $(PREBUILT_STATIC_LIBRARY) # prepare libX include $(CLEAR_VARS) TARGET_ARCH_ABI := armeabi-v7a LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/include LOCAL_MODULE := avutil LOCAL_SRC_FILES := libavutil.a include $(PREBUILT_STATIC_LIBRARY) # prepare libX include $(CLEAR_VARS) TARGET_ARCH_ABI := armeabi-v7a LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/include LOCAL_MODULE := postproc LOCAL_SRC_FILES := libpostproc.a include $(PREBUILT_STATIC_LIBRARY) # prepare libX include $(CLEAR_VARS) TARGET_ARCH_ABI := armeabi-v7a LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/include LOCAL_MODULE := swresample LOCAL_SRC_FILES := libswresample.a include $(PREBUILT_STATIC_LIBRARY) # prepare libX include $(CLEAR_VARS) TARGET_ARCH_ABI := armeabi-v7a LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/include LOCAL_MODULE := swscale LOCAL_SRC_FILES := libswscale.a include $(PREBUILT_STATIC_LIBRARY) # prepare libX include $(CLEAR_VARS) TARGET_ARCH_ABI := armeabi-v7a LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/include LOCAL_MODULE := x264 LOCAL_SRC_FILES := libx264.a include $(PREBUILT_STATIC_LIBRARY) include $(CLEAR_VARS) TARGET_ARCH_ABI := armeabi-v7a LOCAL_MODULE := NativeAppTest LOCAL_SRC_FILES := NativeAppTest.cpp LOCAL_C_INCLUDES += $(LOCAL_PATH)/include LOCAL_CFLAGS := -D__STDC_CONSTANT_MACROS -Wno-sign-compare -Wno-switch -Wno-pointer-sign -DHAVE_NEON=1 -mfpu=neon -mfloat-abi=softfp -fPIC -DANDROID LOCAL_STATIC_LIBRARIES := avfilter avformat avcodec postproc swresample swscale avutil x264 LOCAL_LDLIBS := -L$(NDK_ROOT)/platforms/$(APP_PLATFORM)/arch-arm/usr/lib -L$(LOCAL_PATH) -llog -ljnigraphics -lz -ldl include $(BUILD_SHARED_LIBRARY)
Application.mk
APP_STL := gnustl_static APP_LDFLAGS := -latomic APP_ABI := armeabi-v7a APP_PLATFORM := android-19
NativeApp.cpp (因为FFmpeg是纯C实现，所以在cpp文件中引用头的时候，需加上[extern "C"]包裹)否则编译将出现如下错误：
jni/NativeAppTest.cpp:21: error: undefined reference to ‘avcodec_configuration()‘ clang++.exe: error: linker command failed with exit code 1 (use -v to see invocation) make: *** [obj/local/armeabi-v7a/libNativeAppTest.so] Error 1
#include <jni.h>
extern "C"{
#include "libavcodec/avcodec.h"
}
#include <com_ltz_nativeapptest_anative_DoInFastMode.h>
/*
* Class: com_ltz_nativeapptest_anative_DoInFastMode
* Method: getVersion
* Signature: ()I
*/
JNIEXPORT jint JNICALL Java_com_ltz_nativeapptest_anative_DoInFastMode_getVersion
(JNIEnv *, jclass){
return 0;
}
JNIEXPORT jstring JNICALL
Java_com_ltz_nativeapptest_anative_DoInFastMode_getCfg
(JNIEnv *env, jclass){
// TODO
char info[10000] = {0};
sprintf(info, "%s\n", avcodec_configuration());
return env->NewStringUTF(info);
}
另外附上JNI目录结构：
______________________________失败部分总结________________________________________
FFmpeg使用了master分支的最新代码，使用NDK r10c和r13b在编译 avcodec都出现了莫名其妙的错误：
1处是aaccoder.c 文件中search_for_ms函数 在初始化B0，B1报符号错误。怀疑变量名与宏冲突，所以改为了BC0，BC1，改文件编译通过。
2处：hevc_mvs.c 文件的宏定义
#define TAB_MVF_PU(v) TAB_MVF(((x ## v) >> s->ps.sps->log2_min_pu_size), ((y ## v) >> s->ps.sps->log2_min_pu_size))
提示找不到x,y 由于不清楚操作符 “##” 代表什么含义，所以暂时还没解决该问题。
时间： 2024-08-13 17:13:36