[Libav-user] Beginner c++ compiling error

mounir younes mounir.younes at gmail.com
Sat Oct 1 22:28:03 CEST 2011


i am using netbeans and in the libraries tab there is a linker command where
i am adding the libs i stated in the thread before. Netbeans is catching the
libs (giving them a lib icon otherwise it would've given them a "blank"
icon) but I am always getting the "undefined reference to <functionName>"
(when using ffmpeg functions). I would really appreciate it if someone can
write a really really really small tutorial that shows how to build ur first
ffmpeg program (using the latest ffmpeg) and run it. That would help a lot
of people other than me for a lot of people are having this problem and some
others after updating ffmpeg.

On Thu, Sep 29, 2011 at 1:39 AM, jan hölscher <jan.hoelscher at codergrid.de>wrote:

> before we can discuss further, please provide the complete command line to
> the linker and error from it.
>
>
>
> 2011/9/29 mounir younes <mounir.younes at gmail.com>
>
>> Yes I did that ! But still having the problem after building.
>>
>>
>> On Wed, Sep 28, 2011 at 7:53 PM, jan hölscher <jan.hoelscher at codergrid.de
>> > wrote:
>>
>>> did you surround your libav header includes with :
>>>
>>> #ifdef __cplusplus
>>> extern "C" {
>>> #endif
>>> #include <libavformat/avformat.h>
>>> #include <libavcodec/avcodec.h>
>>> #include <libavcodec/opt.h>
>>> #include <libavutil/avutil.h>
>>> #include <libswscale/swscale.h>
>>> #include <libavutil/fifo.h>
>>> #include <libavutil/rational.h>
>>> #ifdef __cplusplus
>>> }
>>> #endif
>>>
>>>
>>> 2011/9/28 mounir younes <mounir.younes at gmail.com>
>>>
>>>> I gave the names without the linker prefix. I keep getting the
>>>> "undefined reference to" error and cannot solve it.
>>>>
>>>> On Sat, Sep 24, 2011 at 10:43 PM, Alex Cohn <alexcohn at netvision.net.il>wrote:
>>>>
>>>>> In your list of libs, "-l" is obviously doubled. Try to give the names
>>>>> to the linker without the prefix.
>>>>>  On Sep 24, 2011 7:58 AM, "mounir younes" <mounir.younes at gmail.com>
>>>>> wrote:
>>>>> > Hello, I am new to ffmpeg and I am getting compiling errors while
>>>>> compiling
>>>>> > c++ code with ffmpeg libraries. It seems that a lot of people are
>>>>> getting
>>>>> > this with the new ffmpeg but I couldn't find a solution that I could
>>>>> > understand.
>>>>> >
>>>>> > I found a link that says that this
>>>>> >
>>>>> > CXXFLAGS=-D__STDC_CONSTANT_MACROS ./configure
>>>>> > (http://code.google.com/p/ffmpegsource/issues/detail?id=11)
>>>>> >
>>>>> >
>>>>> > solves it but unfortunately I tried it but nothing happened and I
>>>>> don't know
>>>>> > what to do ! I am adding the file headers which are being
>>>>> automatically
>>>>> > detected by netbeans so the libraries are already found. I tried
>>>>> adding
>>>>> > these -lavdevice -lavformat -lavcodec -lavutil -lswscale -lbz2 to the
>>>>> > linker as well
>>>>> >
>>>>> > (
>>>>> >
>>>>> http://libav-users.943685.n4.nabble.com/QT-and-FFmpeg-undefined-reference-to-av-free-and-more-td946811.html
>>>>> > )
>>>>> >
>>>>> > when adding them netbeans knew them and gave them proper library
>>>>> icons (thus
>>>>> > it recognized that these libraries are present otherwise it would've
>>>>> > replaced them with a white icon with question mark). But, when
>>>>> compiling I
>>>>> > get this
>>>>> >
>>>>> > /usr/bin/ld: cannot find -l-lavdevice
>>>>> > /usr/bin/ld: cannot find -l-lavformat
>>>>> > /usr/bin/ld: cannot find -l-lavcodec
>>>>> > /usr/bin/ld: cannot find -l-lavutil
>>>>> > /usr/bin/ld: cannot find -l-lswscale
>>>>> > /usr/bin/ld: cannot find -l-lbz2
>>>>> >
>>>>> > And this is really killing me. I have been trying to solve this for
>>>>> days.
>>>>> >
>>>>> > Thank you in advance.
>>>>>
>>>>> _______________________________________________
>>>>> Libav-user mailing list
>>>>> Libav-user at ffmpeg.org
>>>>> http://ffmpeg.org/mailman/listinfo/libav-user
>>>>>
>>>>>
>>>>
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>>>>
>>>>
>>>
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>>>
>>
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>
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