libavformat无法在macOS上链接

Question

我正在尝试通过FFMPEG教程，但是当我尝试构建项目时，我会收到以下错误。我首先认为Cmake的find_path和find_library正在链接错误的文件mark setchell表明事实并非如此。现在，我不确定为什么会发生链接器错误。这是未能编译和上述错误的最低示例。

[build] [1/1 100% :: 0.076] Linking CXX executable example
[build] FAILED: example 
[build] : && /usr/bin/clang++ -g -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX12.1.sdk -Wl,-search_paths_first -Wl,-headerpad_max_install_names -L/usr/local/opt/llvm/lib CMakeFiles/example.dir/main.cpp.o -o example  /usr/local/lib/libavformat.dylib && :
[build] Undefined symbols for architecture x86_64:
[build]   "avformat_open_input(AVFormatContext**, char const*, AVInputFormat const*, AVDictionary**)", referenced from:
[build]       _main in main.cpp.o
[build]   "avformat_free_context(AVFormatContext*)", referenced from:
[build]       _main in main.cpp.o
[build]   "avformat_alloc_context()", referenced from:
[build]       _main in main.cpp.o
[build] ld: symbol(s) not found for architecture x86_64
[build] clang: error: linker command failed with exit code 1 (use -v to see invocation)
[build] ninja: build stopped: subcommand failed.

cmakelists.txt：

cmake_minimum_required(VERSION 3.21)
set(CMAKE_CXX_STANDARD 17)


find_path(AVFORMAT_INCLUDE_DIRS libavformat/avformat.h REQUIRED)
find_library(AVFORMAT_LIBRARY avformat REQUIRED)

message(WARNING "AVFORMAT_LIBRARY=" ${AVFORMAT_LIBRARY})
message(WARNING "AVFORMAT_INCLUDE_DIRS=" ${AVFORMAT_INCLUDE_DIRS})

add_executable(example main.cpp)
target_link_libraries(example ${AVFORMAT_LIBRARY})
target_include_directories(example PRIVATE ${AVFORMAT_INCLUDE_DIRS})

main.cpp：

#include <libavformat/avformat.h>

#include <stdio.h>


int main(int argc, char **argv) {
    if (argc < 2) {
        printf("example <input_file>");
        exit(EXIT_FAILURE);
    }

    AVFormatContext *pFormatContext = avformat_alloc_context();

    avformat_open_input(&pFormatContext, argv[1], nullptr, nullptr);
    printf("Format %s, duration %lld us", pFormatContext->iformat->long_name, pFormatContext->duration);


    avformat_free_context(pFormatContext);
}