一、编译选项如下

test : all
	$(CC) $(CXXFLAGS)  -I/DecoderFFMPEGLive/ -o Test/$@.o -c Test/test.cpp
	$(CC) $(CXXFLAGS) -o $@ Test/$@.o -L. -lDecoderFFMPEGLive   -lpthread

报错误：/usr/bin/ld: cannot open output file test: Is a directory

是因为我想生成test的执行文件，但是当前目录有一个Test文件夹，导致报错，将-o $@修改成-o   $@demo(任意字符都可)

二、修改一之后，报错误

/usr/bin/ld: cannot find -lDecoderFFMPEGLive

编译知识太差导致我在这个问题浪费了好多时间，是因为我生成的库名字是libDecoderFFMPEGLive.so.1.0.0.7，我以为这样也能识别到......，想了好久，最后面突然开悟，将libDecoderFFMPEGLive.so.1.0.0.7重命名为libDecoderFFMPEGLive.so解决问题，当然也可以加软链接

三、

g++ -g -Wall -O3  -I/home/lis/code/DecoderFFMPEGLive/DecoderFFMPEGLive -I./comlib/ffmpeg/include -I./comlib/boost_1_71_0/include -I./comlib/XDevToolbox_release/include -std=c++11 -fPIC -fvisibility=hidden -o testdemo Test/test.o -lDecoderFFMPEGLive -L. -lpthread
./libDecoderFFMPEGLive.so: undefined reference to `x264_param_default'
./libDecoderFFMPEGLive.so: undefined reference to `x264_param_apply_profile'
./libDecoderFFMPEGLive.so: undefined reference to `x264_encoder_headers'
./libDecoderFFMPEGLive.so: undefined reference to `x264_encoder_encode'
./libDecoderFFMPEGLive.so: undefined reference to `avpriv_codec2_mode_bit_rate'
./libDecoderFFMPEGLive.so: undefined reference to `x264_encoder_reconfig'
./libDecoderFFMPEGLive.so: undefined reference to `x264_param_apply_fastfirstpass'
./libDecoderFFMPEGLive.so: undefined reference to `x264_encoder_delayed_frames'
./libDecoderFFMPEGLive.so: undefined reference to `x264_param_parse'
./libDecoderFFMPEGLive.so: undefined reference to `x264_levels'
./libDecoderFFMPEGLive.so: undefined reference to `x264_picture_init'
./libDecoderFFMPEGLive.so: undefined reference to `x264_encoder_close'
./libDecoderFFMPEGLive.so: undefined reference to `av_bitstream_filter_filter'
./libDecoderFFMPEGLive.so: undefined reference to `avpriv_codec2_mode_frame_size'
./libDecoderFFMPEGLive.so: undefined reference to `x264_param_default_preset'
./libDecoderFFMPEGLive.so: undefined reference to `x264_encoder_open_164'
./libDecoderFFMPEGLive.so: undefined reference to `avpriv_codec2_mode_block_align'
./libDecoderFFMPEGLive.so: undefined reference to `av_adts_header_parse'

使用nm命令查找动态库，发现未定义此函数，需要找libDecoderFFMPEGLive.so的问题

 

排查发现是libDecoderFFMPEGLive.so没有包含-lx264选项，加上即解决。

四、下面的函数都是在libavcodec中的，libDecoderFFMPEGLive.so明明加了-lavcodec选项，还是U(未定义)，好奇怪

 最后是在编译可执行程序时再加了-lavcodec才编译过(这里还是没理清楚为什么这样)

$(CC) $(CXXFLAGS) -o $@ Test/$@.o -L. -lDecoderFFMPEGLive -L$(FFMPEG_DIR)/lib -lavcodec -lpthread