我在使用 mingw64 编译器构建 ffmpeg 时遇到了麻烦。这是我的配置：
./configure --prefix=/home/ytan/Dev/build-mingw/ffmpeg/ --enable-cross-compile --cross-prefix=x86_64-w64-mingw32- --arch=x86_64 --target-os=mingw64 --pkg-config-flags="--static" --enable-shared --disable-static --enable-libvpx --enable-libvorbis --enable-libmp3lame --enable-openssl --enable-pic --enable-debug --extra-ldlibflags="-static"
当我运行 make 时，链接失败：
(...lot of text omitted)
LD libavcodec/avcodec-57.dll
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(onyx_if.c.o):(.text+0x408d): undefined reference to `sem_post'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(onyx_if.c.o):(.text+0x408d): relocation truncated to fit: R_X86_64_PC32 against undefined symbol `sem_post'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(onyx_if.c.o):(.text+0x4d33): undefined reference to `sem_post'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(onyx_if.c.o):(.text+0x4d33): relocation truncated to fit: R_X86_64_PC32 against undefined symbol `sem_post'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(onyx_if.c.o):(.text+0x6a62): undefined reference to `sem_wait'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(onyx_if.c.o):(.text+0x6a62): relocation truncated to fit: R_X86_64_PC32 against undefined symbol `sem_wait'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(onyx_if.c.o):(.text+0x8965): undefined reference to `sem_wait'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(onyx_if.c.o):(.text+0x8965): relocation truncated to fit: R_X86_64_PC32 against undefined symbol `sem_wait'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(threading.c.o):(.text+0x563): undefined reference to `sched_yield'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(threading.c.o):(.text+0x563): relocation truncated to fit: R_X86_64_PC32 against undefined symbol `sched_yield'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(threading.c.o):(.text+0x16f6): undefined reference to `sem_post'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(threading.c.o):(.text+0x16f6): relocation truncated to fit: R_X86_64_PC32 against undefined symbol `sem_post'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(threading.c.o):(.text+0x174b): undefined reference to `sem_wait'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(threading.c.o):(.text+0x174b): relocation truncated to fit: R_X86_64_PC32 against undefined symbol `sem_wait'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(threading.c.o):(.text+0x18a9): undefined reference to `sem_init'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(threading.c.o):(.text+0x18a9): relocation truncated to fit: R_X86_64_PC32 against undefined symbol `sem_init'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(threading.c.o):(.text+0x191b): undefined reference to `pthread_create'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(threading.c.o):(.text+0x191b): relocation truncated to fit: R_X86_64_PC32 against undefined symbol `pthread_create'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(threading.c.o):(.text+0x194e): undefined reference to `sem_init'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(threading.c.o):(.text+0x194e): relocation truncated to fit: R_X86_64_PC32 against undefined symbol `sem_init'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(threading.c.o):(.text+0x19bb): undefined reference to `sem_destroy'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(threading.c.o):(.text+0x19bb): additional relocation overflows omitted from the output
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(threading.c.o):(.text+0x19f4): undefined reference to `sem_destroy'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(threading.c.o):(.text+0x220e): undefined reference to `sem_post'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(threading.c.o):(.text+0x2224): undefined reference to `pthread_join'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(threading.c.o):(.text+0x2252): undefined reference to `sem_destroy'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(threading.c.o):(.text+0x22e8): undefined reference to `sem_destroy'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(threading.c.o):(.text+0x26a2): undefined reference to `sem_post'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(threading.c.o):(.text+0x26d4): undefined reference to `sem_wait'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(encodeframe.c.o):(.text+0x1b36): undefined reference to `sched_yield'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(encodeframe.c.o):(.text+0x21a2): undefined reference to `sem_post'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(encodeframe.c.o):(.text+0x24d5): undefined reference to `sched_yield'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(encodeframe.c.o):(.text+0x2757): undefined reference to `sem_wait'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(encodeframe.c.o):(.text+0x3259): undefined reference to `sem_post'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(ethreading.c.o):(.text+0x27): undefined reference to `sem_wait'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(ethreading.c.o):(.text+0x5d): undefined reference to `sem_post'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(ethreading.c.o):(.text+0x100): undefined reference to `sem_wait'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(ethreading.c.o):(.text+0x2f3): undefined reference to `sched_yield'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(ethreading.c.o):(.text+0x7cb): undefined reference to `sem_post'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(ethreading.c.o):(.text+0x10f9): undefined reference to `sem_init'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(ethreading.c.o):(.text+0x117c): undefined reference to `sem_init'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(ethreading.c.o):(.text+0x11ac): undefined reference to `pthread_create'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(ethreading.c.o):(.text+0x11ef): undefined reference to `pthread_join'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(ethreading.c.o):(.text+0x1202): undefined reference to `sem_destroy'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(ethreading.c.o):(.text+0x120f): undefined reference to `sem_destroy'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(ethreading.c.o):(.text+0x1287): undefined reference to `sem_init'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(ethreading.c.o):(.text+0x1294): undefined reference to `sem_init'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(ethreading.c.o):(.text+0x12b7): undefined reference to `pthread_create'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(ethreading.c.o):(.text+0x12e0): undefined reference to `sem_post'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(ethreading.c.o):(.text+0x12f2): undefined reference to `pthread_join'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(ethreading.c.o):(.text+0x1305): undefined reference to `sem_destroy'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(ethreading.c.o):(.text+0x1313): undefined reference to `sem_destroy'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(ethreading.c.o):(.text+0x131b): undefined reference to `sem_destroy'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(ethreading.c.o):(.text+0x1323): undefined reference to `sem_destroy'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(ethreading.c.o):(.text+0x13f3): undefined reference to `sem_init'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(ethreading.c.o):(.text+0x1400): undefined reference to `sem_init'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(ethreading.c.o):(.text+0x1423): undefined reference to `pthread_create'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(ethreading.c.o):(.text+0x147e): undefined reference to `sem_post'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(ethreading.c.o):(.text+0x1490): undefined reference to `pthread_join'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(ethreading.c.o):(.text+0x14a3): undefined reference to `sem_destroy'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(ethreading.c.o):(.text+0x14ba): undefined reference to `sem_post'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(ethreading.c.o):(.text+0x14c8): undefined reference to `pthread_join'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(ethreading.c.o):(.text+0x14d4): undefined reference to `sem_destroy'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(ethreading.c.o):(.text+0x14e0): undefined reference to `sem_destroy'
/home/ytan/Dev/build-mingw/libvpx/lib/libvpx.a(ethreading.c.o):(.text+0x14e8): undefined reference to `sem_destroy'
collect2: error: ld returned 1 exit status
library.mak:102: recipe for target 'libavcodec/avcodec-57.dll' failed
make: *** [libavcodec/avcodec-57.dll] Error 1
sem_post似乎指向 mingw64 编译器使用的 pthread，但将其添加到--host-cflags="-lpthread"似乎没有帮助。有什么想法吗？
答案1
添加 后--extra-ldlibflags="-pthread"它就正常工作了。我想这不是因为我把它添加到了错误的地方，而是因为我应该使用-pthread而不是-lpthread。它们是有区别的。
现在我的配置命令是这样的：
./configure --prefix=/home/ytan/Dev/build-mingw/ffmpeg/ --enable-cross-compile --cross-prefix=x86_64-w64-mingw32- --arch=x86_64 --target-os=mingw64 --pkg-config-flags="--static" --enable-shared --disable-static --enable-libvpx --enable-libvorbis --enable-libmp3lame --enable-openssl --enable-pic --enable-debug --extra-ldlibflags="-static -pthread"