Here's my problem:
Can anyone help me? Thanks...
edit: here are a few of the undefined reference messages:
./libns3.14.1-qoe-monitor-debug.so: undefined reference to `av_guess_format'
./libns3.14.1-qoe-monitor-debug.so: undefined reference to `av_read_frame'
./libns3.14.1-qoe-monitor-debug.so: undefined reference to `avformat_write_header'
./libns3.14.1-qoe-monitor-debug.so: undefined reference to `av_interleaved_write_frame'
./libns3.14.1-qoe-monitor-debug.so: undefined reference to `av_find_stream_info'
./libns3.14.1-qoe-monitor-debug.so: undefined reference to `av_register_all'
./libns3.14.1-qoe-monitor-debug.so: undefined reference to `av_init_packet'
./libns3.14.1-qoe-monitor-debug.so: undefined reference to `avformat_alloc_context'
./libns3.14.1-qoe-monitor-debug.so: undefined reference to `av_dump_format'
./libns3.14.1-qoe-monitor-debug.so: undefined reference to `avio_close'
edit2: here is the message I get after "build failed":
-> task in 'scratch-simulator' failed (exit status 1):
{task 53952272: cxxprogram scratch-simulator.cc.1.o -> scratch-simulator}
['/usr/bin/g++', '-I/usr/local/include/libavcodec', '-I/usr/local/include/libavformat/',
'-I/usr/local/include/libavutil/', '-L/usr/local/lib', '-I/usr/local
/include/libavcodec', '-I/usr/local/include/libavformat/', '-I/usr/local/include
/libavutil/', '-L/usr/local/lib', '-pthread', '-pthread', '-Wl,-z,relro',
'scratch/scratch-simulator.cc.1.o', '-o', '/home/fede/Thesis/ns-allinone-3.14.1
/ns-3.14.1/build/scratch/scratch-simulator', '-Wl,-Bstatic', '-Wl,-Bdynamic',
'-Wl,--no-as-needed', '-L.', '-L.', '-L.', '-L.', '-L.', '-L.', '-L.', '-L.', '-L.',
'-L.', '-L.', '-L.', '-L.', '-L.', '-L.', '-L.', '-L.', '-L.', '-L.', '-L.', '-L.',
'-L.', '-L.', '-L.', '-L.', '-L.', '-L.', '-L.', '-L.', '-L.', '-L.', '-L.', '-L.',
'-L.', '-L.', '-L.', '-L.', '-L.', '-L/usr/lib', '-lns3.14.1-test-debug', '-lns3.14.1-
csma-layout-debug', '-lns3.14.1-point-to-point-layout-debug', '-lns3.14.1-netanim-
debug', '-lns3.14.1-lte-debug', '-lns3.14.1-spectrum-debug', '-lns3.14.1-antenna-
debug', '-lns3.14.1-aodv-debug', '-lns3.14.1-dsdv-debug', '-lns3.14.1-dsr-debug',
'-lns3.14.1-mesh-debug', '-lns3.14.1-olsr-debug', '-lns3.14.1-csma-debug', '-lns3.14.1-
wimax-debug', '-lns3.14.1-applications-debug', '-lns3.14.1-virtual-net-device-debug',
'-lns3.14.1-uan-debug', '-lns3.14.1-energy-debug', '-lns3.14.1-flow-monitor-debug',
'-lns3.14.1-nix-vector-routing-debug', '-lns3.14.1-tap-bridge-debug', '-lns3.14.1-
visualizer-debug', '-lns3.14.1-internet-debug', '-lns3.14.1-bridge-debug', '-lns3.14.1-
point-to-point-debug', '-lns3.14.1-mpi-debug', '-lns3.14.1-wifi-debug', '-lns3.14.1-
buildings-debug', '-lns3.14.1-propagation-debug', '-lns3.14.1-mobility-debug',
'-lns3.14.1-config-store-debug', '-lns3.14.1-tools-debug', '-lns3.14.1-stats-debug',
'-lns3.14.1-emu-debug', '-lns3.14.1-topology-read-debug', '-lns3.14.1-network-debug',
'-lns3.14.1-qoe-monitor-debug', '-lns3.14.1-core-debug', '-lrt', '-lgsl',
'-lgslcblas', '-lm', '-ldl', '-lgtk-x11-2.0', '-lgdk-x11-2.0', '-latk-1.0',
'-lgio-2.0', '-lpangoft2-1.0', '-lpangocairo-1.0', '-lgdk_pixbuf-2.0', '-lcairo',
'-lpango-1.0', '-lfreetype', '-lfontconfig', '-lgobject-2.0', '-lglib-2.0', '-lxml2',
'-lpython2.7']
So when we try to assign it a value in the main function, the linker doesn't find the symbol and may result in an “unresolved external symbol” or “undefined reference”. The way to fix this error is to explicitly scope the variable using '::' outside the main before using it.
If you get an error about "undefined reference" when compiling a program of your own from source code, then you are probably missing to include some required symbols which should be distributed in a separate library archive.
The libraries are C. The library headers don't include an extern "C" when compiled as C++. Do this in your C++ source:
extern "C" {
#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
}
Or, more generically, for mixed C and C++ source:
#ifdef __cplusplus
extern "C" {
#endif
#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
#ifdef __cplusplus
}
#endif
And you should be fine.
I had this problem with av_find_stream_info
and the problem was this function was deprecated. The problem was I had two ffmpeg installation on the box, and it was reading header from one installation and was using libraries from different installation.
After removing system default library, the problem resolved.
UPDATE: For Ubuntu I did following:
$ sudo dpkg -r libavcodec53
$ sudo dpkg -r libavformat53
$ sudo dpkg -r libavutil51
$ sudo dpkg -r libswscale2
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