undefined reference to `avcodec_register_all'在android中编译出现的问题

undefined reference to `avcodec_register_all'
这个怎么解决

#include "include/com_dreamiii_testffmpeg_FFmpegNative.h"
#include "prebuild/libavcodec/avcodec.h"
#include "prebuild/libavutil/avutil.h"

JNIEXPORT jstring JNICALL Java_com_dreamiii_testffmpeg_FFmpegNative_hello
        (JNIEnv *env, jobject obj){
    avcodec_register_all();
    char wd[512];
    sprintf(wd,"avcodec_version %u\n",avcodec_version());
    return (*env)->NewStringUTF(env,"hello jni");
}

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http://www.roman10.net/how-to-build-ffmpeg-with-ndk-r9/
可以参考一下这个