How to properly link ffmpeg project in eclipse linux

Question

I have a little test project on linux eclipse using ffmpeg. It is oke to make it using command line

g++ -o m_vector -I/usr/include -I/usr/local/include m_vector.cpp -lavformat -lavcodec -lavutil -lm -lz -lva -lpthread

but in eclipse while linking i get a big list of errors

/home/user/projects/ffmpeg/libavcodec/internal.h:194: undefined reference to `av_rescale_q'
/usr/local/lib/libavcodec.a(mpegvideo.o): In function `update_picture_tables':
/home/user/projects/ffmpeg/libavcodec/mpegvideo.c:663: undefined reference to `av_buffer_unref'
/home/user/projects/ffmpeg/libavcodec/mpegvideo.c:663: undefined reference to `av_buffer_ref'
/home/user/projects/ffmpeg/libavcodec/mpegvideo.c:664: undefined reference to `av_buffer_unref'
/home/user/projects/ffmpeg/libavcodec/mpegvideo.c:664: undefined reference to `av_buffer_ref'
/home/user/projects/ffmpeg/libavcodec/mpegvideo.c:665: undefined reference to `av_buffer_unref'
/home/user/projects/ffmpeg/libavcodec/mpegvideo.c:665: undefined reference to `av_buffer_ref'

and so on

I've aded the needed libs in project and i use "extern c". My project knows also about needed includes. Digging internet did not give the answer.

Answer 1

Swap the order of the libraries you're linking to, one depends on the other. The one that is depended on the most must be last, in this case libavutil.

Answer 2

The libraries will be searched in path_to_gcc/usr/lib. Hopefully you bmay not having the libraries there.Add -L$path-to-libraries

Answer 3

Ubuntu different Windows OS.
Ubuntu sort lib, so you can add lib like this:
-lavdevice -lavformat -lavcodec -lavutil -lswscale -lavfilter -lpthread -lz -lm -lswresample
After add finish. If you have error: undefined reference to vaCreateBuffer... then you should rebuild ffmpeg and disable -lva lib.
Example: You build in: https://trac.ffmpeg.org/wiki/CompilationGuide/Ubuntu
Replace lines PATH to:
PATH="$HOME/bin:$PATH" PKG_CONFIG_PATH="$HOME/ffmpeg_build/lib/pkgconfig"
./configure \\
--prefix="$HOME/ffmpeg_build" \\
--pkg-config-flags="--static" \\
--extra-cflags="-I$HOME/ffmpeg_build/include" \\
--extra-ldflags="-L$HOME/ffmpeg_build/lib" \\
--bindir="$HOME/bin" \\
--disable-vaapi
I don't build libx264, libx265, libfdk-aac..... b/c I don't need. If you need, you can build.
Line code: --disable-vaapi is disable -lva lib.