必须包括所有“file.o”文件，其中有“#include”file.h“。

Question

/path/to/cross/compiler/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian/bin/../lib/gcc/arm-linux-gnueabihf/4.7.2/../../../../arm-linux-gnueabihf/bin/ld: warning: libavutil.so.51, needed by /mnt/root/usr/lib/arm-linux-gnueabihf/libpostproc.so.52, may conflict with libavutil.so.52
BitstreamConverter.o: In function `DllAvUtilBase::av_frame_move_ref(AVFrame*, AVFrame*)':
BitstreamConverter.cpp:(.text._ZN13DllAvUtilBase17av_frame_move_refEP7AVFrameS1_[_ZN13DllAvUtilBase17av_frame_move_refEP7AVFrameS1_]+0x8): undefined reference to `av_frame_move_ref'
BitstreamConverter.o: In function `DllAvUtilBase::av_frame_unref(AVFrame*)':
BitstreamConverter.cpp:(.text._ZN13DllAvUtilBase14av_frame_unrefEP7AVFrame[_ZN13DllAvUtilBase14av_frame_unrefEP7AVFrame]+0x4): undefined reference to `av_frame_unref'
BitstreamConverter.o: In function `DllAvUtilBase::av_frame_alloc()':
BitstreamConverter.cpp:(.text._ZN13DllAvUtilBase14av_frame_allocEv[_ZN13DllAvUtilBase14av_frame_allocEv]+0x0): undefined reference to `av_frame_alloc'
BitstreamConverter.o: In function `DllAvUtilBase::av_frame_free(AVFrame**)':
BitstreamConverter.cpp:(.text._ZN13DllAvUtilBase13av_frame_freeEPP7AVFrame[_ZN13DllAvUtilBase13av_frame_freeEPP7AVFrame]+0x4): undefined reference to `av_frame_free'
collect2: error: ld returned 1 exit status
make: *** [omxplayer.bin] Error 1

Makefile：

SRC=linux/XMemUtils.cpp \
        utils/log.cpp \
        DynamicDll.cpp \
        utils/PCMRemap.cpp \
        utils/RegExp.cpp \
        OMXSubtitleTagSami.cpp \
        OMXOverlayCodecText.cpp \
        BitstreamConverter.cpp \
        linux/RBP.cpp \
        OMXThread.cpp \
        OMXReader.cpp \
        OMXStreamInfo.cpp \
        OMXAudioCodecOMX.cpp \
        OMXCore.cpp \
        OMXVideo.cpp \
        OMXAudio.cpp \
        OMXClock.cpp \
        File.cpp \
        OMXPlayerVideo.cpp \
        OMXPlayerAudio.cpp \
        OMXPlayerSubtitles.cpp \
        SubtitleRenderer.cpp \
        Unicode.cpp \
        Srt.cpp \
        KeyConfig.cpp \
        OMXControl.cpp \
        Keyboard.cpp \
        omxplayer.cpp \

OBJS+=$(filter %.o,$(SRC:.cpp=.o))

all: omxplayer.bin

%.o: %.cpp
    @rm -f $@ 
    $(CXX) $(CFLAGS) $(INCLUDES) -c $< -o $@ -Wno-deprecated-declarations

version:
    bash gen_version.sh > version.h 

omxplayer.bin: version $(OBJS)
    $(CXX) $(LDFLAGS) -o omxplayer.bin $(OBJS) -lvchiq_arm -lvcos -lrt -lpthread -lavutil -lavcodec -lavformat -lavdevice -lavfilter -lswscale -lswresample -lpcre `./arm-linux-gnueabihf-pkg-config --libs dbus-1` -lrt
    #arm-unknown-linux-gnueabi-strip omxplayer.bin

clean:
    for i in $(OBJS); do (if test -e "$$i"; then ( rm $$i ); fi ); done
    @rm -f omxplayer.old.log omxplayer.log
    @rm -f omxplayer.bin
    @rm -rf $(DIST)
    @rm -f omxplayer-dist.tar.gz

ffmpeg:
    @rm -rf ffmpeg
    make -f Makefile.ffmpeg
    make -f Makefile.ffmpeg install

dist: omxplayer.bin
    mkdir -p $(DIST)/usr/lib/omxplayer
    mkdir -p $(DIST)/usr/bin
    mkdir -p $(DIST)/usr/share/doc
    cp omxplayer omxplayer.bin $(DIST)/usr/bin
    cp COPYING $(DIST)/usr/share/doc/
    cp README.md $(DIST)/usr/share/doc/README
    cp -a ffmpeg_compiled/usr/local/lib/*.so* $(DIST)/usr/lib/omxplayer/
    tar -czf omxplayer-dist.tar.gz $(DIST)

Answer 1

看起来需要在编译时从.o文件中拉入函数定义。我发现这篇文章非常有助于解释这背后的理论：

http://eli.theGreenplace.net/2013/07/09/Library-Order-in-Static-Linking/

关于链接和编译的更多信息，我也强烈推荐这本书：http://www.network-theory.co.uk/docs/gccintro/index.html