[Libav-user] 'Undefined reference'-error when using functions of libavcodec, compiling in Linux

[Anders Branderud]

Thanks for the reply!
The error generated is not because of missing header-files. The
header-files isn't missing.
[See also this thead:
http://stackoverflow.com/questions/9701764/undefined-reference-using-ffmpeg-library-avcodec-on-ubuntu-64-bits-system]

The same error is generated including the header-files specifically (see
below) (that otherwise automatically are added):
gcc videofecencoder.cc -I/usr/include/libavcodec -I/usr/include/libavformat
-I/usr/include/libavutil -lavformat -lavcodec -lavutil
/tmp/cc7FFtFo.o: In function `video_encode_example(char const*, int)':
videofecencoder.cc:(.text+0x30): undefined reference to
`avcodec_find_encoder(CodecID)'
videofecencoder.cc:(.text+0x75): undefined reference to
`avcodec_alloc_context3(AVCodec*)'
videofecencoder.cc:(.text+0x7d): undefined reference to
`avcodec_alloc_frame()'
videofecencoder.cc:(.text+0xfc): undefined reference to `av_opt_set(void*,
char const*, char const*, int)'
videofecencoder.cc:(.text+0x116): undefined reference to
`avcodec_open2(AVCodecContext*, AVCodec*, AVDictionary**)'
videofecencoder.cc:(.text+0x1e2): undefined reference to
`av_image_alloc(unsigned char**, int*, int, int, PixelFormat, int)'
videofecencoder.cc:(.text+0x330): undefined reference to
`avcodec_encode_video(AVCodecContext*, unsigned char*, int, AVFrame const*)'
videofecencoder.cc:(.text+0x3b3): undefined reference to
`avcodec_encode_video(AVCodecContext*, unsigned char*, int, AVFrame const*)'
videofecencoder.cc:(.text+0x464): undefined reference to
`avcodec_close(AVCodecContext*)'
videofecencoder.cc:(.text+0x46f): undefined reference to `av_free(void*)'
videofecencoder.cc:(.text+0x47c): undefined reference to `av_free(void*)'
videofecencoder.cc:(.text+0x487): undefined reference to `av_free(void*)'
/tmp/cc7FFtFo.o: In function `main':
videofecencoder.cc:(.text+0x4a8): undefined reference to
`avcodec_register_all()'
collect2: ld returned 1 exit status


2012/3/16 Andrey Utkin <andrey.krieger.utkin at gmail.com>

> 2012/3/16 Anders Branderud <anders.branderud at gmail.com>:
> > Hello!
> >
> > When I run the encoding example (code inserted to the following cc-file)
> > provided in doc/examples of the FFMpeg-library and compile it with the
> > line linux-y8h9:/home/anders/Programs # g++ videofecencoder.cc -lavformat
> > -lavcodec -lavutil
> >
> > I get the following error message:
> > /tmp/ccDQpTY5.o: In function `video_encode_example(char const*, int)':
> > videofecencoder.cc:(.text+0x30): undefined reference to
> > `avcodec_find_encoder(CodecID)'
> > videofecencoder.cc:(.text+0x75): undefined reference to
> > `avcodec_alloc_context3(AVCodec*)'
> > videofecencoder.cc:(.text+0x7d): undefined reference to
> > `avcodec_alloc_frame()'
> > videofecencoder.cc:(.text+0xfc): undefined reference to
> `av_opt_set(void*,
> > char const*, char const*, int)'
> > videofecencoder.cc:(.text+0x116): undefined reference to
> > `avcodec_open2(AVCodecContext*, AVCodec*, AVDictionary**)'
> > videofecencoder.cc:(.text+0x1e2): undefined reference to
> > `av_image_alloc(unsigned char**, int*, int, int, PixelFormat, int)'
> > videofecencoder.cc:(.text+0x330): undefined reference to
> > `avcodec_encode_video(AVCodecContext*, unsigned char*, int, AVFrame
> const*)'
> > videofecencoder.cc:(.text+0x3b3): undefined reference to
> > `avcodec_encode_video(AVCodecContext*, unsigned char*, int, AVFrame
> const*)'
> > videofecencoder.cc:(.text+0x464): undefined reference to
> > `avcodec_close(AVCodecContext*)'
> > videofecencoder.cc:(.text+0x46f): undefined reference to `av_free(void*)'
> > videofecencoder.cc:(.text+0x47c): undefined reference to `av_free(void*)'
> > videofecencoder.cc:(.text+0x487): undefined reference to `av_free(void*)'
> > /tmp/ccDQpTY5.o: In function `main':
> > videofecencoder.cc:(.text+0x4a8): undefined reference to
> > `avcodec_register_all()'
> > collect2: ld returned 1 exit status
> >
> > I have tried the same using two different Ubuntu-installations. The above
> > compilation was performed using OpenSUSE installed in a VirtualBox. I did
> > the above at a new installation of OpenSUSE. After installing it I
> > downloaded the required libraries using the libraries provided in the
> > Software repository called 'PackMan'.
>
> You lack libraries' header files. Find and install packages that
> contain files /usr/include/libavformat/avformat.h,
> /usr/include/libavcodec/avcodec.h . I hope you got the point. I don't
> know exact package names for suse and ubuntu.
>
> --
> Andrey Utkin
> _______________________________________________
> Libav-user mailing list
> Libav-user at ffmpeg.org
> http://ffmpeg.org/mailman/listinfo/libav-user
>



-- 
*Kind regards,*

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