Android上的FFMpeg，未定义的对libavcodec函数的引用，尽管它在命令行中列出

时间：2011-03-17 10:31:59

标签： android ffmpeg android-ndk

我对ffmpeg的libavcodec函数的未解析引用有问题，到目前为止未能在其他地方找到答案（包括我的想法）:)

让我描述一下我的设置 - 它需要空间，但实际上是基本的，可能是因为我没有看到一些错误......

我使用ndk r5工具链构建了一个FFMPeg，ffmpeg是我从http://bambuser.com/opensource获得的端口（在此处的其他问题中推荐）。它构建得很好，所以我在我的项目中放了几个静态库：

<project>/jni/bambuser_ffmpeg/libavcodec.a
<project>/jni/bambuser_ffmpeg/libavformat.a
<project>/jni/bambuser_ffmpeg/libavcore.a
<project>/jni/bambuser_ffmpeg/libavutil.a

接下来，我在bambuser_ffmpeg文件夹中创建了一个Android.mk，将这些库列为预建库：

LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)
LOCAL_MODULE := bambuser-libavcore
LOCAL_SRC_FILES := libavcore.a
include $(PREBUILT_STATIC_LIBRARY)

include $(CLEAR_VARS)
LOCAL_MODULE := bambuser-libavformat
LOCAL_SRC_FILES := libavformat.a
include $(PREBUILT_STATIC_LIBRARY)

(same for other two libs)

接下来，我有另一个模块在其Android.mk中引用这些库，设置包含路径等：

LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)

LOCAL_MODULE := ffmpegtest
LOCAL_STATIC_LIBRARIES := bambuser-libavcodec bambuser-libavcore bambuser-libavformat bambuser-libavutil
LOCAL_SRC_FILES := ffmpeg_test.cpp
LOCAL_C_INCLUDES := $(LOCAL_PATH)/../bambuser_ffmpeg/include
LOCAL_LDLIBS    := -llog -lz

include $(BUILD_SHARED_LIBRARY)

最后我的ffmpeg_test.cpp非常基本，就像这样：

#include <jni.h>

extern "C" {
#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
}

extern "C" {
    JNIEXPORT jint JNICALL Java_com_the7art_ffmpegtest_PaintThread_testFFMpeg(JNIEnv* env, jobject obj, jstring fileName);
}

JNIEXPORT jint JNICALL Java_com_the7art_ffmpegtest_PaintThread_testFFMpeg(JNIEnv* env, jobject obj, jstring fileName)
{
    av_register_all();
    return 0;
}

当我运行 ndk-build 时，它编译得很好，但是在链接时会打印出一个未解析的引用，几乎是 libavcodec 中的每个函数。看起来只有这个lib的功能无法找到：

/home/dimka/src/mobile/android/ffmpegtest/obj/local/armeabi/libavformat.a(allformats.o): In function `av_register_all':
/home/dimka/work/suzy/tmp/ffmpeg-android/ffmpeg/libavformat/allformats.c:47: undefined reference to `avcodec_register_all'
/home/dimka/src/mobile/android/ffmpegtest/obj/local/armeabi/libavformat.a(utils.o): In function `parse_frame_rate':
/home/dimka/work/suzy/tmp/ffmpeg-android/ffmpeg/libavformat/utils.c:3240: undefined reference to `av_parse_video_rate'
/home/dimka/src/mobile/android/ffmpegtest/obj/local/armeabi/libavformat.a(utils.o): In function `parse_image_size':
/home/dimka/work/suzy/tmp/ffmpeg-android/ffmpeg/libavformat/utils.c:3234: undefined reference to `av_parse_video_size'
/home/dimka/src/mobile/android/ffmpegtest/obj/local/armeabi/libavformat.a(utils.o): In function `flush_packet_queue':
/home/dimka/work/suzy/tmp/ffmpeg-android/ffmpeg/libavformat/utils.c:1277: undefined reference to `av_free_packet'
/home/dimka/work/suzy/tmp/ffmpeg-android/ffmpeg/libavformat/utils.c:1283: undefined reference to `av_free_packet'
/home/dimka/src/mobile/android/ffmpegtest/obj/local/armeabi/libavformat.a(utils.o): In function `get_audio_frame_size':
/home/dimka/work/suzy/tmp/ffmpeg-android/ffmpeg/libavformat/utils.c:766: undefined reference to `av_get_bits_per_sample'
/home/dimka/src/mobile/android/ffmpegtest/obj/local/armeabi/libavformat.a(utils.o): In function `ff_interleave_add_packet':
/home/dimka/work/suzy/tmp/ffmpeg-android/ffmpeg/libavformat/utils.c:2909: undefined reference to `av_dup_packet'
and so on...

我无法弄清楚为什么会这样。我尝试运行 ndk-build V = 1 来检查实际的链接命令，并且 libavcodec 完全正确地坐在那里，就像它应该的那样。所有其他ffmpeg库也都在那里。

任何提示？

3 个答案:

答案 0 :(得分：5)

以下Android.mk适用于我，包括处理目标arch。运行bambuser build.sh的结果从... / build / ffmpeg复制到/ jni / lib / ffmpeg。 OP正在使用PREBUILD_SHARED_LIBRARY而不是PREBUILT_STATIC_LIBRARY。

LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)
LOCAL_MODULE := libavcodec
LOCAL_SRC_FILES := lib/ffmpeg/$(TARGET_ARCH_ABI)/lib/$(LOCAL_MODULE).so
LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/lib/ffmpeg/$(TARGET_ARCH_ABI)/include
include $(PREBUILT_SHARED_LIBRARY)

include $(CLEAR_VARS)
LOCAL_MODULE := libavcore
LOCAL_SRC_FILES := lib/ffmpeg/$(TARGET_ARCH_ABI)/lib/$(LOCAL_MODULE).so
LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/lib/ffmpeg/$(TARGET_ARCH_ABI)/include
include $(PREBUILT_SHARED_LIBRARY)

include $(CLEAR_VARS)
LOCAL_MODULE := libavdevice
LOCAL_SRC_FILES := lib/ffmpeg/$(TARGET_ARCH_ABI)/lib/$(LOCAL_MODULE).so
LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/lib/ffmpeg/$(TARGET_ARCH_ABI)/include
include $(PREBUILT_SHARED_LIBRARY)

include $(CLEAR_VARS)
LOCAL_MODULE := libavfilter
LOCAL_SRC_FILES := lib/ffmpeg/$(TARGET_ARCH_ABI)/lib/$(LOCAL_MODULE).so
LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/lib/ffmpeg/$(TARGET_ARCH_ABI)/include
include $(PREBUILT_SHARED_LIBRARY)

include $(CLEAR_VARS)
LOCAL_MODULE := libavformat
LOCAL_SRC_FILES := lib/ffmpeg/$(TARGET_ARCH_ABI)/lib/$(LOCAL_MODULE).so
LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/lib/ffmpeg/$(TARGET_ARCH_ABI)/include
include $(PREBUILT_SHARED_LIBRARY)

include $(CLEAR_VARS)
LOCAL_MODULE := libavutil
LOCAL_SRC_FILES := lib/ffmpeg/$(TARGET_ARCH_ABI)/lib/$(LOCAL_MODULE).so
LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/lib/ffmpeg/$(TARGET_ARCH_ABI)/include
include $(PREBUILT_SHARED_LIBRARY)

include $(CLEAR_VARS)
LOCAL_MODULE := libswscale
LOCAL_SRC_FILES := lib/ffmpeg/$(TARGET_ARCH_ABI)/lib/$(LOCAL_MODULE).so
LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/lib/ffmpeg/$(TARGET_ARCH_ABI)/include
include $(PREBUILT_SHARED_LIBRARY)

include $(CLEAR_VARS)

LOCAL_MODULE    := mynativecode
LOCAL_SRC_FILES := native.c
LOCAL_SHARED_LIBRARIES := libavcore libavdevice libavfilter libavutil libswscale libavformat
LOCAL_LDLIBS := -L$(NDK_PLATFORMS_ROOT)/$(TARGET_PLATFORM)/arch-arm/usr/lib \
                -L$(LOCAL_PATH)/lib/ffmpeg/$(TARGET_ARCH_ABI)/lib \
                -lavcore \
                -lavformat \
                -lavcodec \
                -lavdevice \
                -lavfilter \
                -lavutil \
                -lswscale \
                -llog \
                -lz \
                -ldl \
                -lgcc

include $(BUILD_SHARED_LIBRARY)

我还必须更改bambuser build.sh来修改--soname-prefix参数以包含我的包名而不是bambusers。

        FLAGS="--target-os=linux --cross-prefix=arm-linux-androideabi- --arch=arm"
        FLAGS="$FLAGS --sysroot=$SYSROOT"
-       FLAGS="$FLAGS --soname-prefix=/data/data/com.bambuser.broadcaster/lib/"
+       FLAGS="$FLAGS --soname-prefix=/data/data/<my package name here>/lib/"
        FLAGS="$FLAGS --enable-shared --disable-symver"
        FLAGS="$FLAGS --enable-small --optimization-flags=-O2"

答案 1 :(得分：2)

我一直在使用ffmpeg进行一些Android工作。我的构建有点不同。我从bambuser.com构建中获取了lib * .a文件和include目录，并直接将它们包含在我的jni目录中，我的Android.mk看起来像这样：

LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)

LOCAL_MODULE    := ndk1
LOCAL_SRC_FILES := native.c

LOCAL_C_INCLUDES := $(LOCAL_PATH)/include
LOCAL_LDLIBS := -L$(NDK_PLATFORMS_ROOT)/$(TARGET_PLATFORM)/arch-arm/usr/lib -L$(LOCAL_PATH) -lavformat -lavcodec -lavdevice -lavfilter -lavutil -lswscale -llog -ljnigraphics -lz -ldl -lgcc

include $(BUILD_SHARED_LIBRARY)

那里可能有一些残骸，但也许它会帮助你找到正确的方向。我试着像你一样遵循NDK示例项目中列出的一些表单。将lib捆绑到一个模块然后引用它。但最终又回到简单的直接包括只是为了让事情有效，到目前为止还没有理由重新审视它。

答案 2 :(得分：0)

当你构建ffmpeg时应该使用android-14或更低版本，如下所示：

export NDK=/Users/luoye/Downloads/android-ndk-r11c
export PREBUILT=$NDK/toolchains/arm-linux-androideabi-4.9/prebuilt
export PLATFORM=$NDK/platforms/android-8/arch-arm
export PREFIX=../simplefflib
build_one(){
./configure --target-os=linux --prefix=$PREFIX \
--enable-cross-compile \
--enable-runtime-cpudetect \
--disable-asm \
--arch=arm \
--cc=$PREBUILT/darwin-x86_64/bin/arm-linux-androideabi-gcc \
--cross-prefix=$PREBUILT/darwin-x86_64/bin/arm-linux-androideabi- \
--disable-stripping \
--nm=$PREBUILT/darwin-x86_64/bin/arm-linux-androideabi-nm \
--sysroot=$PLATFORM \
--enable-gpl --enable-shared --disable-static --enable-small \
--disable-ffprobe
--disable-ffplay
--disable-ffmpeg
--disable-ffserver
--disable-debug \
--extra-cflags="-fPIC -DANDROID -D__thumb__ -mthumb -Wfatal-errors -         Wno-deprecated -mfloat-abi=softfp -marm -march=armv7-a" 
}

build_one

make
make install
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