[vlc-devel] How to GDB into MJPEG decoder - What source file to set breakpoint?

Ed Sutton ESutton at fescorp.com
Mon Jan 26 19:45:25 CET 2009

> > I run GDB and try unsuccessfully to hit a breakpoint in one of the
> > libvacodec modules using:
> >
> > gdb /usr/local/av/bin/vlc
> > (gdb) break mjpegdec.c:ff_mjpeg_decode_sof
> > (gdb) #gdb says no source file found and I tell it "Yes" to put a
> > breakpoint on future *shared library load* (gdb) Run -vvv
> udp://@:1234
> >
> > Is my problem that gdb never finds the ffmpeg symbolic info?  Or am I
> in
> > the wrong source code?
> That symbol should be in libavformat or libavcodec, which are linked
> from the respective VLC plugins.

When I do a "ldd vlc" I did not see either. I assume that these two shared libraries are not loaded until the VLC runs which explains why the ldd utility does not know about them.  

What is the name of the VLC plugin that would be calling the M-JPEG decoder?  Sorry, I cannot find much describing VLC plugins. 

Is a plugin is a run-time loaded module that performs a task such as M-JPEG decoding?

I'm working full time trying to learn VLC, and your tips have been very helpful, out but I think I am still missing the big picture on how a frame-based decoder such as M-JPEG is implemented.

Thanks again,

More information about the vlc-devel mailing list