Undefined Reference Error, Can Not Create Shared Library

Tried so many ways to solve problem but no luck. Here is my Android.mk: LOCAL_PATH := $(call my-dir) include $(CLEAR_VARS) LOCAL_MODULE := avcodec LOCAL_SRC_FILES :=libavcodec.a

Solution 1:

Make sure you have added the extern "C" block around the include of the libavcodec and swscale headers, e.g. like this:

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

See 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 for documentation that explains this.

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EDIT: Also, are you sure that the prebuilt libavcodec.a is for the same architecture (armeabi-v7a) as you're building? If you are building your shared library for multiple architectures (armeabi-v7a, x86, etc) you need to have multiple corresponding versions of the prebuilt libraries as well.

Solution 2:

Try ndk-build V=1 to see the actual command that links your library. You want to end up with

-lavformat -lavcodec -lavfilter -lavutil -lswscale

in that order (as here), but I am not sure where avresample swresample x264 should fit. Rearrange your LOCAL_STATIC_LIBRARIES accordingly.