无法使用LOCAL_LDLIBS + = -lmediandk找到libmediandk.so。 具有ndk-build的Android本机共享库

Question

Why can I not find libmediandk.so with the following command in the Android.mk file:

LOCAL_LDLIBS    += -lmediandk

Application.mk

NDK_TOOLCHAIN_VERSION := 4.9
APP_ABI := x86

Android.mk

LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)
LOCAL_CFLAGS += -std=c++11
LOCAL_CFLAGS    += -UNDEBUG
LOCAL_LDLIBS    += -lmediandk
LOCAL_LDLIBS    += -OpenMAXAL
LOCAL_LDLIBS    += -landroid 
LOCAL_SHARED_LIBRARIES += libmediandk
LOCAL_LDLIBS    += -llog
CC=/home/c/Downloads/Openglxmlfour/i686-linux-android/bin/i686-linux-android-gcc
CXX=CC=/home/c/Downloads/Openglxmlfour/i686-linux-android/bin/i686-linux-android-g++
LOCAL_MODULE    := native-codec-jni  # name your module here.
LOCAL_SRC_FILES := native-codec-jni.cpp looper.cpp
LOCAL_C_INCLUDES=/home/c/Android/Sdk/ndk-bundle/platforms/android-21/arch-x86/usr/include
include $(BUILD_SHARED_LIBRARY)

Command Line

ndk-build clean && ndk-build 
[x86] Clean          : native-codec-jni [x86]
[x86] Clean          : stdc++ [x86]
[x86] Compile++      : native-codec-jni <= native-codec-jni.cpp
[x86] Compile++      : native-codec-jni <= looper.cpp
[x86] StaticLibrary  : libstdc++.a
[x86] SharedLibrary  : libnative-codec-jni.so
/home/c/Android/Sdk/ndk-bundle/toolchains/x86-4.9/prebuilt/linux-x86_64/bin/../lib/gcc/i686-linux-android/4.9.x/../../../../i686-linux-android/bin/ld: error: cannot find -lmediandk




   /home/c/Downloads/android-ndk-master2/MyApplication/app/src/main/jni/native-codec-jni.cpp:94: error: undefined reference to 'AMediaCodec_dequeueInputBuffer'
    /home/c/Downloads/android-ndk-master2/MyApplication/app/src/main/jni/native-codec-jni.cpp:98: error: undefined reference to 'AMediaCodec_getInputBuffer'
    /home/c/Downloads/android-ndk-master2/MyApplication/app/src/main/jni/native-codec-jni.cpp:99: error: undefined reference to 'AMediaExtractor_readSampleData'
    /home/c/Downloads/android-ndk-master2/MyApplication/app/src/main/jni/native-codec-jni.cpp:105: error: undefined reference to 'AMediaExtractor_getSampleTime'
    /home/c/Downloads/android-ndk-master2/MyApplication/app/src/main/jni/native-codec-jni.cpp:108: error: undefined reference to 'AMediaCodec_queueInputBuffer'
    /home/c/Downloads/android-ndk-master2/MyApplication/app/src/main/jni/native-codec-jni.cpp:109: error: undefined reference to 'AMediaExtractor_advance'
    /home/c/Downloads/android-ndk-master2/MyApplication/app/src/main/jni/native-codec-jni.cpp:115: error: undefined reference to 'AMediaCodec_dequeueOutputBuffer'
    /home/c/Downloads/android-ndk-master2/MyApplication/app/src/main/jni/native-codec-jni.cpp:129: error: undefined reference to 'AMediaCodec_releaseOutputBuffer'
    /home/c/Downloads/android-ndk-master2/MyApplication/app/src/main/jni/native-codec-jni.cpp:137: error: undefined reference to 'AMediaCodec_getOutputFormat'
    /home/c/Downloads/android-ndk-master2/MyApplication/app/src/main/jni/native-codec-jni.cpp:138: error: undefined reference to 'AMediaFormat_toString'
    /home/c/Downloads/android-ndk-master2/MyApplication/app/src/main/jni/native-codec-jni.cpp:139: error: undefined reference to 'AMediaFormat_delete'
    /home/c/Downloads/android-ndk-master2/MyApplication/app/src/main/jni/native-codec-jni.cpp:172: error: undefined reference to 'AMediaExtractor_seekTo'
    /home/c/Downloads/android-ndk-master2/MyApplication/app/src/main/jni/native-codec-jni.cpp:173: error: undefined reference to 'AMediaCodec_flush'
    /home/c/Downloads/android-ndk-master2/MyApplication/app/src/main/jni/native-codec-jni.cpp:161: error: undefined reference to 'AMediaCodec_stop'
    /home/c/Downloads/android-ndk-master2/MyApplication/app/src/main/jni/native-codec-jni.cpp:162: error: undefined reference to 'AMediaCodec_delete'
    /home/c/Downloads/android-ndk-master2/MyApplication/app/src/main/jni/native-codec-jni.cpp:163: error: undefined reference to 'AMediaExtractor_delete'
    /home/c/Downloads/android-ndk-master2/MyApplication/app/src/main/jni/native-codec-jni.cpp:237: error: undefined reference to 'AMediaExtractor_new'
    /home/c/Downloads/android-ndk-master2/MyApplication/app/src/main/jni/native-codec-jni.cpp:240: error: undefined reference to 'AMediaExtractor_setDataSourceFd'
    /home/c/Downloads/android-ndk-master2/MyApplication/app/src/main/jni/native-codec-jni.cpp:247: error: undefined reference to 'AMediaExtractor_getTrackCount'
    /home/c/Downloads/android-ndk-master2/MyApplication/app/src/main/jni/native-codec-jni.cpp:275: error: undefined reference to 'AMediaFormat_delete'
    /home/c/Downloads/android-ndk-master2/MyApplication/app/src/main/jni/native-codec-jni.cpp:253: error: undefined reference to 'AMediaExtractor_getTrackFormat'
    /home/c/Downloads/android-ndk-master2/MyApplication/app/src/main/jni/native-codec-jni.cpp:254: error: undefined reference to 'AMediaFormat_toString'
    /home/c/Downloads/android-ndk-master2/MyApplication/app/src/main/jni/native-codec-jni.cpp:257: error: undefined reference to 'AMEDIAFORMAT_KEY_MIME'
    /home/c/Downloads/android-ndk-master2/MyApplication/app/src/main/jni/native-codec-jni.cpp:257: error: undefined reference to 'AMediaFormat_getString'
    /home/c/Downloads/android-ndk-master2/MyApplication/app/src/main/jni/native-codec-jni.cpp:263: error: undefined reference to 'AMediaExtractor_selectTrack'
    /home/c/Downloads/android-ndk-master2/MyApplication/app/src/main/jni/native-codec-jni.cpp:264: error: undefined reference to 'AMediaCodec_createDecoderByType'
    /home/c/Downloads/android-ndk-master2/MyApplication/app/src/main/jni/native-codec-jni.cpp:265: error: undefined reference to 'AMediaCodec_configure'
    /home/c/Downloads/android-ndk-master2/MyApplication/app/src/main/jni/native-codec-jni.cpp:273: error: undefined reference to 'AMediaCodec_start'
    collect2: error: ld returned 1 exit status
    make: *** [/home/c/Downloads/android-ndk-master2/MyApplication/app/src/main/obj/local/x86/libnative-codec-jni.so] Error 1

Answer 1

libmediandk was first added to android-21 ( https://android-review.googlesource.com/#/c/278674/1/media/ndk/Android.bp ). You haven't stated an APP_PLATFORM in your Application.mk, so you're defaulting to android-9.

To get access to libmediandk, set APP_PLATFORM := android-21 in your Application.mk. Note that this will make Lollipop the minimum supported platform for your application.