Re: [vox-tech] inline keyword solves "undefined reference" issue

[Hai Yi <yihMAPSai2004@gmail.com>]

Thanks Jeff. However, the header file of those C routines are included in ffmpegmgr.h, which is in turn included by ffmpegmgr.cpp.

The "undefined reference " normally indicates that the functions's definitions are not found, and it takes place when doing the linker. The libraries, libavcodec, etc, have been specified from the g++ command line, and seems to work - only that I need to make the encapulated member function in ffmpegmgr.cpp inline to eliminate the linker error:

inline void FFMpegMgr::new_video_stream(AVFormatContext *oc)
{
   ...
    st = av_new_stream(oc, oc->nb_streams);
   ...
}

Also, the lib that I specified is *.a, will it be different if the lib is *.so ?

Thanks,
Hai

On Mon, Jun 7, 2010 at 1:26 AM, Jeff Newmiller <jdnewmil@dcn.davis.ca.us> wrote:

Seems more likely that you haven't included the declarations for the C routines in your cpp file. Would need to see more context to diagnose.

"Hai Yi" <yihai2004@gmail.com> wrote:

>Hello all:
>
>I created a class FFMpegMgr and a method init(); inside init() I just put
>three ffmpeg api there:
>avcodec_register_all();
>avdevice_register_all();
> av_register_all();
>
>The source file ffmpegmgr.cpp look like this:
>
> void FFMpegMgr::init() {
>    avcodec_register_all();
>    avdevice_register_all();
>    av_register_all();
>
>}
>
>Now I got a "undefined reference to avcodec_register_all" error.
>
>if I put that body in the class declaration or add a "inline" keyword, that
>problem was gone and the compilation succeeded.
>
>question is, do those three functions, which are C functions defined in
>avcodec.h,  have to be used only in the inline functions in C++?
>
>Sorry if it appear naive - I've been out of touch with C/C++ for a while.
>
>Thanks!
>Hai

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