Question

I’m having problems building a project under the Android NDK. Most likely its due to the proper shared / static libraries not being included. The ones as -lsomeLib I added, but the ones as LOCAL_SHARED_LIBRARIES are not being included it seems…

My Android.mk contains the following

LOCAL_SHARED_LIBRARIES += libutils libmedia libz libbinder

1. Where does ndk-build actually look for these libraries?
2. If I don’t include the -lutils -lmedia -lz -lbinder, I am not able to even get to the linker error. I have a feeling including just -LsomeDir and -lsomeLib is not the correct way to add them.

Here is the complete Android.mk.

LOCAL_PATH := /Users/kevin/Desktop/player2/videoplayer/videoplayer/jni
LIBPLAYER_PATH := $(LOCAL_PATH)/../../LibPlayer

include $(CLEAR_VARS)

$(warning Android make file: $(LOCAL_PATH)/Android.mk)
$(warning Android sysroot: $(SYSROOT))
$(warning Additional LD_LIBS: $(LOCAL_PATH)/lib)

ifeq ($(BUILD_ID),MID)
        LOCAL_CFLAGS += -DENABLE_FREE_SCALE
endif

LOCAL_MODULE    := libamplayerjni
LOCAL_SRC_FILES := com_farcore_playerservice_AmPlayer.c sys_conf.c
LOCAL_ARM_MODE := arm
LOCAL_C_INCLUDES := $(LIBPLAYER_PATH)/amplayer/player/include \
    $(LIBPLAYER_PATH)/amplayer/control/include \
    $(LIBPLAYER_PATH)/amcodec/include \
    $(LIBPLAYER_PATH)/amffmpeg \
    $(JNI_H_INCLUDE) \
    /Android/ndk/build/tools/android-9-toolchain/sysroot/usr/include \
    /Android/ndk/build/platforms/android-9/arch-arm/usr/include \
    /Android/source_2.3/system/core/include \
    /Android/source_2.3/frameworks/base/include

LOCAL_LDLIBS := -L/Users/kevin/Desktop/player2/videoplayer/videoplayer/jni/lib -L$(SYSROOT)/usr/lib -llog -lz -lm -ldl **-lmedia -lstagefright -lutils -lbinder -lgcc -landroid -lc -lstdc++ -lthread_db**

**LOCAL_STATIC_LIBRARIES := libamplayer libamcodec libavformat libavcodec libavutil libamadec**
LOCAL_SHARED_LIBRARIES += libutils libmedia libz libbinder 

LOCAL_PRELINK_MODULE := false

include $(BUILD_SHARED_LIBRARY)

One of many errors related specifically to those libraries (ie libmedia.so).

/Users/kevin/Desktop/player2/videoplayer/videoplayer/obj/local/armeabi-v7a/libamadec.a(android_out.o): In function `android_uninit':
/Users/kevin/Desktop/player2/videoplayer/LibPlayer/amadec/audio_out/android_out.cpp:220: undefined reference to `android::AudioTrack::stop()'
/Users/kevin/Desktop/player2/videoplayer/LibPlayer/amadec/audio_out/android_out.cpp:228: undefined reference to `android::AudioTrack::~AudioTrack()'
/Users/kevin/Desktop/player2/videoplayer/videoplayer/obj/local/armeabi-v7a/libamadec.a(android_out.o): In function `~Autolock':

Answer 1

It looks to me like you should not be including -lmedia etc in your LOCAL_LDLIBS arguments.

1. Where does ndk-build actually look for these libraries?

If you look in $NDK/docs/STABLE-APIS.html you will see that there is a specified set of libraries you can include in this manner. Note:


The headers corresponding to a given API level are now located under $NDK/platforms/android-<level>/arch-arm/usr/include


Having looked myself, none of the libraries you specified exist there, although I only looked for API-14.

---

2. If I don’t include the -lutils -lmedia -lz -lbinder, I am not able to even get to the linker error. I have a feeling including just -LsomeDir and -lsomeLib is not the correct way to add them.

If your libraries are just regular c/c++ libraries that you would #include you should use LOCAL_C_INCLUDES instead.

Also note, from $NDK/docs/ANDROID-MK.html:

• The build system handles many details for you. For example, you
  don’t need to list header files or explicit dependencies between
  generated files in your Android.mk. The NDK build system will
  compute these automatically for you.

In order to use other libraries in my native code, I simply #include it and then specify where to find the headers. Here’s my LOCAL_C_INCLUDES:

LOCAL_C_INCLUDES := $(LOCAL_PATH)/shared/Core/inc \
                    $(LOCAL_PATH)/shared/Model/inc  \
                    $(LOCAL_PATH)/shared/boost/include

I hope this helps.