Integrating OpenMP in VLC

I'm trying to make OpenMP work with VLC (Android version) but with no success.

As recommended by Google, I added this to the Android.mk (/vlc-android/libvlc/jni) file:

LOCAL_CFLAGS += -fopenmp
LOCAL_LDFLAGS += -fopenmp

But I keep getting:

error: undefined reference to 'omp_set_num_threads'
error: undefined reference to 'omp_get_thread_num'
error: undefined reference to 'omp_get_num_threads'

I wonder if anyone can help me to overcome this error.

Android.mk:

LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)
LOCAL_MODULE := libvlc
ARCH=$(APP_ABI)
LOCAL_SRC_FILES += libvlcjni-modules.c libvlcjni-symbols.c dummy.cpp
LOCAL_LDFLAGS := -L$(VLC_CONTRIB)/lib
LOCAL_LDLIBS := \
    $(VLC_MODULES) \
    $(VLC_BUILD_DIR)/lib/.libs/libvlc.a \
    $(VLC_BUILD_DIR)/src/.libs/libvlccore.a \
    $(VLC_BUILD_DIR)/compat/.libs/libcompat.a \
    $(VLC_CONTRIB_LDFLAGS) \
    -ldl -lz -lm -llog \
    -lliveMedia -lUsageEnvironment -lBasicUsageEnvironment -lgroupsock \
    -la52 -ljpeg \
    -lavcodec -lebml \
    -llua \
    -lgcrypt -lgpg-error \
    $(VLC_LDFLAGS)

include $(BUILD_SHARED_LIBRARY)

include $(CLEAR_VARS)
LOCAL_MODULE    := libvlcjni

LOCAL_SRC_FILES := libvlcjni.c
LOCAL_SRC_FILES += libvlcjni-mediaplayer.c
LOCAL_SRC_FILES += libvlcjni-vlcobject.c
LOCAL_SRC_FILES += libvlcjni-media.c libvlcjni-medialist.c libvlcjni-mediadiscoverer.c
LOCAL_SRC_FILES += libvlcjni-dialog.c
LOCAL_SRC_FILES += thumbnailer.c
LOCAL_SRC_FILES += std_logger.c

LOCAL_LDLIBS := -llog
LOCAL_C_INCLUDES := $(VLC_SRC_DIR)/include

ARCH=$(APP_ABI)

LOCAL_CFLAGS := -std=c11
ifeq ($(ARCH), armeabi-v7a)
    LOCAL_CFLAGS += -DHAVE_ARMEABI_V7A
endif

LOCAL_SHARED_LIBRARIES:= libvlc

include $(BUILD_SHARED_LIBRARY)

Solution

For future users, I managed to solve this by adding:

LOCAL_CFLAGS := -std=c99 -fopenmp

and -lgomp to LOCAL_LDLIBS:

LOCAL_LDLIBS := \
    $(VLC_MODULES) \
    $(VLC_BUILD_DIR)/lib/.libs/libvlc.a \
    $(VLC_BUILD_DIR)/src/.libs/libvlccore.a \
    $(VLC_BUILD_DIR)/compat/.libs/libcompat.a \
    $(VLC_CONTRIB_LDFLAGS) \
    -ldl -lz -lm -llog \
    -lliveMedia -lUsageEnvironment -lBasicUsageEnvironment -lgroupsock \
    -la52 -ljpeg \
    -lavcodec -lebml \
    -llua -lgomp \
    -lgcrypt -lgpg-error \
    $(VLC_LDFLAGS)

Reference: OpenMP library specification