Question

我正在编写一个包含2个内部库的应用程序，并依赖于更多2个外部库（ffmpeg和opencv）。我也使用CMake生成UNIX makefile。问题是当我尝试构建源代码时，它会编译但根本不与ffmpeg链接，并且链接器会给出下一个输出：

../../Decoder/libDecoder.a(ConverterAVFrameToRGB.cpp.o): In function `FaceVideo::ConverterAVFrameToRGB::to_rgb_conversion(std::vector<AVFrame*, std::allocator<AVFrame*> >&, int, int, int)':
ConverterAVFrameToRGB.cpp:(.text+0x990): undefined reference to `av_frame_free'
../../Decoder/libDecoder.a(FfmpegDecoder.cpp.o): In function `FaceVideo::FfmpegDecoder::destroy()':
FfmpegDecoder.cpp:(.text+0xa30): undefined reference to `av_frame_free'
../../Decoder/libDecoder.a(FfmpegDecoder.cpp.o): In function `FaceVideo::FfmpegDecoder::decode_next_chunk(int)':
FfmpegDecoder.cpp:(.text+0xb6b): undefined reference to `av_frame_clone'
FfmpegDecoder.cpp:(.text+0xc13): undefined reference to `av_frame_free'
../../Decoder/libDecoder.a(FfmpegEncoder.cpp.o): In function `FaceVideo::FfmpegEncoder::destroy()':
FfmpegEncoder.cpp:(.text+0x132): undefined reference to `avcodec_free_frame'
../../Decoder/libDecoder.a(FfmpegEncoder.cpp.o): In function `FaceVideo::FfmpegEncoder::encode()':
FfmpegEncoder.cpp:(.text+0x4c4): undefined reference to `avcodec_encode_video2'
FfmpegEncoder.cpp:(.text+0x592): undefined reference to `avcodec_encode_video2'
../../Decoder/libDecoder.a(FrameSaver.cpp.o): In function `FaceVideo::FrameSaver::saver(std::vector<AVFrame*, std::allocator<AVFrame*> >&, int, int, int)':
FrameSaver.cpp:(.text+0x869): undefined reference to `av_frame_free'
collect2: ld returned 1 exit status

令人兴奋的是我不想看到的。

有三个Cmake文件：两个用于内部库（使用

add_library(Decoder ${SOURCES_DECODER})
             and 
add_library(Detector ${SOURCES_DETECTOR})

在其中）和一个用于主要可执行文件（使用

add_executable(Tool ${SOURCES_TOOL})
             and
target_link_libraries (Tool Decoder avutil avcodec swscale avformat Detector ${OpenCV_LIBS})

in。）

据我所知，从CMake手册和示例中，这应该使链接器将这些库链接在一起，但没有效果。

我一直在尝试很多事情，例如：
1）将link_directories()添加到库的路径（/ usr / lib / x86_64-linux-gnu / for me），无论何时可能，都没有改变。
2）分别链接每个库，我的意思是我尝试在我的内部库CMake文件中执行类似的操作：target_link_libraries (Decoder avutil avcodec swscale avformat)。然后将库链接到我的Tool CMake文件中：target_link_libraries (Tool Decoder Detector)。
3）编辑输出makefile 4）编译简单的单文件应用程序只是为了测试我是否可以做到。我可以。 g++ -lavcodec -o out mysource.cpp完美无缺 5）手动编译ffmpeg并安装它。

事实上，我真的不知道该怎么做。我不知道。我非常感谢你的每一个答案。

UPD1： 设置CMAKE_VERBOSE_MAKEFILE时的输出

！ / usr / bin / c ++ -march = x86-64 -Wall -fPIC -pthread -std = c ++ 0x -D__STDC_CONSTANT_MACROS -march = x86-64 -fPIC CMakeFiles / FaceDetectorTool.dir / home / anton / Programming / facevideo / branches /Stream_Prototype/src/tools/FaceDetectorTool/facedetector.cpp.o -o FaceDetectorTool -rdynamic ../../Detector/libDetector.a ../../Decoder/libDecoder.a -lavutil -lavcodec -lswscale -lavformat / usr / local / lib / libopencv_videostab.so.2.4.7 /usr/local/lib/libopencv_video.so.2.4.7 /usr/local/lib/libopencv_ts.a /usr/local/lib/libopencv_superres.so.2.4。 7 /usr/local/lib/libopencv_stitching.so.2.4.7 /usr/local/lib/libopencv_photo.so.2.4.7 /usr/local/lib/libopencv_ocl.so.2.4.7 / usr / local / lib / libopencv_objdetect.so.2.4.7 /usr/local/lib/libopencv_nonfree.so.2.4.7 /usr/local/lib/libopencv_ml.so.2.4.7 /usr/local/lib/libopencv_legacy.so.2.4.7 / usr / local / lib / libopencv_imgproc.so.2.4.7 /usr/local/lib/libopencv_highgui.so.2.4.7 /usr/local/lib/libopencv_gpu.so.2.4.7 / usr / local / lib / libopencv_flann。 so.2.4.7 / usr / local / lib / lib opencv_features2d.so.2.4.7 /usr/local/lib/libopencv_core.so.2.4.7 /usr/local/lib/libopencv_contrib.so.2.4.7 /usr/local/lib/libopencv_calib3d.so.2.4.7 - ldl -lm -lpthread -lrt /usr/local/lib/libopencv_nonfree.so.2.4.7 /usr/local/lib/libopencv_ocl.so.2.4.7 /usr/local/lib/libopencv_gpu.so.2.4.7 / usr / local / lib / libopencv_photo.so.2.4.7 /usr/local/lib/libopencv_objdetect.so.2.4.7 /usr/local/lib/libopencv_legacy.so.2.4.7 / usr / local / lib / libopencv_video。 so.2.4.7 /usr/local/lib/libopencv_ml.so.2.4.7 /usr/local/lib/libopencv_calib3d.so.2.4.7 /usr/local/lib/libopencv_features2d.so.2.4.7 / usr / local / lib / libopencv_highgui.so.2.4.7 /usr/local/lib/libopencv_imgproc.so.2.4.7 /usr/local/lib/libopencv_flann.so.2.4.7 /usr/local/lib/libopencv_core.so。 2.4.7 -Wl，-rpath，/ usr / local / lib

UPD2 Cmake示例看起来就是这样。

cmake_minimum_required (VERSION 2.8)
project (Decoder)
include(../CMakeInit.cmake)
include_directories(${FFMPEG_INCLUDE_DIR})
include_directories(${Stream_Facevideo_SOURCE_DIR}/../src/kernel/decoder/)
include_directories(${Stream_Facevideo_SOURCE_DIR}/../src/kernel/stuff/)
set(SOURCES_VIDEODECODER
            *sources*
  )

if(WINDOWS)
    set(SOURCES_VIDEODECODER    ${SOURCES_VIDEODECODER} 
            *headers*                           
    )
endif(WINDOWS)

set (SOURCES_DECODER
    ${SOURCES_VIDEODECODER}
)

add_library(Decoder ${SOURCES_DECODER})
link_directories("/usr/lib/x86_64-linux-gnu/")
target_link_libraries(Decoder swscale avformat avcodec avutil)

Answer 1

您的问题似乎忘了为ffmpeg lib添加LINK_DIRECTORIES。

如果没关系，那么尝试更改target_link_libraries中可执行文件的链接顺序，或者为内部库添加target_link_libraries，使用外部库。

Answer 2

似乎这个解决方案应该有效：Findavutil.cmake＆amp; CMakeLists.txt

Ffmpeg使用CMake链接问题

2 个答案: