未定义的引用错误，无法创建共享库

Undefined reference error, can not create shared library

本文关键字：创建 共享 引用 错误 未定义      更新时间：2023-10-16

尝试了很多解决问题的方法，但没有运气。这是我 Android.mk：

LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)  
LOCAL_MODULE := avcodec
LOCAL_SRC_FILES :=libavcodec.a
include $(PREBUILT_STATIC_LIBRARY)
include $(CLEAR_VARS)   
LOCAL_MODULE := avutil
LOCAL_SRC_FILES :=libavutil.a
include $(PREBUILT_STATIC_LIBRARY)
include $(CLEAR_VARS) 
LOCAL_MODULE := swscale
LOCAL_SRC_FILES :=libswscale.a
include $(PREBUILT_STATIC_LIBRARY)
include $(CLEAR_VARS)  
LOCAL_MODULE := avformat
LOCAL_SRC_FILES :=libavformat.a
include $(PREBUILT_STATIC_LIBRARY)
include $(CLEAR_VARS)   
LOCAL_MODULE := avresample
LOCAL_SRC_FILES :=libavresample.a
include $(PREBUILT_STATIC_LIBRARY)

include $(CLEAR_VARS)   
LOCAL_MODULE := swresample
LOCAL_SRC_FILES :=libswresample.a
include $(PREBUILT_STATIC_LIBRARY)
include $(CLEAR_VARS) 
LOCAL_MODULE :=     x264
LOCAL_SRC_FILES :=libx264.a
include $(PREBUILT_STATIC_LIBRARY)
include $(CLEAR_VARS)  
#------------------------------------------
LOCAL_C_INCLUDES := $(LOCAL_PATH)
$(LOCAL_PATH)/include
LOCAL_MODULE    := media
LOCAL_SRC_FILES := 
P_Decoding.cpp 
P_Encoding.cpp 
wrapper_for_ffmpeg.cpp
LOCAL_CPPFLAGS := -std=c++11 -pthread -frtti -fexceptions
LOCAL_ARM_MODE := arm 
LOCAL_STATIC_LIBRARIES := avcodec avutil swscale avformat avresample swresample x264
LOCAL_LDLIBS :=  -llog -ljnigraphics -landroid -lz -lEGL
LOCAL_CPP_FEATURES :=  rtti exceptions 
include $(BUILD_SHARED_LIBRARY)

在 jni 文件夹中，有与 makefile 上.cpp文件相关的所有头 .hpp 文件，还有所有静态 .a 库和"include"文件夹，其中所有与静态库相关的头文件都在。我使用的是 ndk9c 版本。这是错误日志的一部分：

[armeabi-v7a] Compile++ thumb: media <= P_Decoding.cpp
[armeabi-v7a] Compile++ thumb: media <= P_Encoding.cpp
[armeabi-v7a] Compile++ thumb: media <= wrapper_for_ffmpeg.cpp
/

home/pro/android-ndk-r9c/toolchains/llvm-3.3/prebuilt/linux-x86/bin/clang++ -wl，-soname，libmedia.so -shared --sysroot=/home/pro/android-ndk-r9c/platforms/android-9/arch-arm ./obj/local/armeabi/objs/media/P_Decoding.o ./obj/local/armeabi/objs/media/P_Encoding.o jni/libavformat.a jni/libavcodec.a jni/libavutil.a jni/libswscale.a -lgcc ./obj/local/armeabi/libgnustl_shared.so -gcc-toolchain/home/pro/android-ndk-r9c/toolchains/arm-linux-androideabi-4.8/prebuilt/linux-x86 -no-canonical-prefixes -target armv5te-none-linux-androideabi -wl,--no-undefined -wl，-z，noexecstack -wl，-z，relro -wl，-z，now -L/home/pro/android-ndk-r9c/platforms/android-9/arch-arm/usr/lib -llog -ljnigraphics -lz -ldl -lgcc/home/pro/android-ndk-r9c/sources/cxx-stl/gnu-libstdc++/4.8/libs/armeabi/libsupc++.a -lc -lm -o ./obj/local/armeabi/libmedia.so

jni/P_Decoding.cpp:10: error: undefined reference to 'avcodec_register_all'
jni/P_Decoding.cpp:17: error: undefined reference to 'avcodec_find_decoder'
jni/P_Decoding.cpp:14: error: undefined reference to 'avcodec_find_decoder_by_name'
jni/P_Decoding.cpp:24: error: undefined reference to 'avcodec_alloc_context3'
jni/P_Decoding.cpp:50: error: undefined reference to 'avcodec_open2'
jni/P_Decoding.cpp:56: error: undefined reference to 'avcodec_alloc_frame'
jni/P_Decoding.cpp:76: error: undefined reference to 'sws_getContext'
jni/P_Decoding.cpp:90: error: undefined reference to 'avcodec_decode_video2'
jni/P_Decoding.cpp:104: error: undefined reference to 'sws_scale'
jni/P_Decoding.cpp:118: error: undefined reference to 'avcodec_close'

请帮忙。提前致谢

确保在 libavcodec 和 swscale 标头的包含周围添加了 extern "C" 块，例如：

extern "C" {
#include <libavcodec/avcodec.h>
#include <libswscale/swscale.h>
}

有关解释这一点的文档，请参阅 https://libav.org/faq.html#I_0027m-using-Libav-from-within-my-C_002b_002b-application-but-the-linker-complains-about-missing-symbols-which-seem-to-be-available_002e。

编辑：另外，您确定预构建的libavcodec.a与您正在构建的架构(armeabi-v7a(相同吗？如果要为多个体系结构(armeabi-v7a、x86 等(构建共享库，则还需要具有预构建库的多个相应版本。

尝试ndk-build V=1以查看链接库的实际命令。你想结束 

-lavformat -lavcodec -lavfilter -lavutil -lswscale

按照这个顺序(如这里(，但我不确定avresample swresample x264应该适合在哪里。相应地重新排列LOCAL_STATIC_LIBRARIES。

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