[gst-devel] building a gst plugin

[vineeth]

On Tue, Mar 16, 2010 at 2:09 PM, Stefan Kost <ensonic at hora-obscura.de>wrote:

> hi,
>
> vineeth wrote:
> > Hi all,
> >   I was going through the Plugin writers guide, and I sincerely feel
> > that the chapter 9
> > <
> http://gstreamer.freedesktop.org/data/doc/gstreamer/head/pwg/html/chapter-building-testapp.html
> >
> > should also describe how to build the test plugin "my_filter"
> >   that was described all the way along and also being used in the test
> > app. BTW, I used the following command to do this,
> >    gcc  `pkg-config --libs --cflags gstreamer-0.10`
> > gstexamplefilter.c --shared -o
> > ~/.gstreamer-0.10/plugins/libexamplefilter.so
> >
> >   But was unable to load it,
> I added a paragraph to
>
> http://gstreamer.freedesktop.org/data/doc/gstreamer/head/pwg/html/part-building.html
> it will show up after next release.
>
> >
> >   I got the following error message, when I ran it through valgrind :
> >
> > ==3068== Memcheck, a memory error detector.
> > ==3068== Copyright (C) 2002-2008, and GNU GPL'd, by Julian Seward et al.
> > ==3068== Using LibVEX rev 1884, a library for dynamic binary translation.
> > ==3068== Copyright (C) 2004-2008, and GNU GPL'd, by OpenWorks LLP.
> > ==3068== Using valgrind-3.4.1-Debian, a dynamic binary instrumentation
> > framework.
> > ==3068== Copyright (C) 2000-2008, and GNU GPL'd, by Julian Seward et al.
> > ==3068== For more details, rerun with: -v
> > ==3068==
> > ==3069== Invalid read of size 1
> > ==3069==    at 0x42DC3D7: g_str_hash (in
> /usr/lib/libglib-2.0.so.0.2000.1)
> > ==3069==    by 0x42AA3FA: g_hash_table_lookup (in
> > /usr/lib/libglib-2.0.so.0.2000.1)
> > ==3069==    by 0x42A3EB6: g_intern_string (in
> > /usr/lib/libglib-2.0.so.0.2000.1)
> > ==3069==    by 0x4095A48: (within /usr/lib/libgstreamer-0.10.so.0.19.0)
> > ==3069==    by 0x4096F51: gst_plugin_load_file (in
> > /usr/lib/libgstreamer-0.10.so.0.19.0)
> > ==3069==    by 0x40A0B8E: (within /usr/lib/libgstreamer-0.10.so.0.19.0)
> > ==3069==    by 0x40A0CA7: gst_registry_scan_path (in
> > /usr/lib/libgstreamer-0.10.so.0.19.0)
> > ==3069==    by 0x40547B2: (within /usr/lib/libgstreamer-0.10.so.0.19.0)
> > ==3069==    by 0x40551AC: (within /usr/lib/libgstreamer-0.10.so.0.19.0)
> > ==3069==    by 0x40568FA: (within /usr/lib/libgstreamer-0.10.so.0.19.0)
> > ==3069==    by 0x42C7DCA: g_option_context_parse (in
> > /usr/lib/libglib-2.0.so.0.2000.1)
> > ==3069==    by 0x4055FA5: gst_init_check (in
> > /usr/lib/libgstreamer-0.10.so.0.19.0)
> > ==3069==  Address 0x1 is not stack'd, malloc'd or (recently) free'd
> >
> > ERROR: Caught a segmentation fault while loading plugin file:
> > /home/pubuntu/.gstreamer-0.10/plugins/libexamplefilter.so
> >
> > Please either:
> > - remove it and restart.
> > - run with --gst-disable-segtrap and debug.
> >                     ....
> >
> >
> >  Any idea about what is going wrong?
>
> what backtrace are you getting when you run this under gdb, e.g. via:
> gdb --args gst-inspect-0.10 --gst-disable-registry-fork examplefilter
>
> Stefan
>

The problem is fixed,
The problem was in the way I was building the plugin, the macro VERSION was
not defined in the generated filter code so I had declared it as a int
leading to the crash.
(I had ignored the gcc warning and later realized this to be a string.)
Probably the template plugin code can have a definition of macro VERSION, so
that the generated filter is compilable out of the box(?).
Thanks.


>
> >  Thanks
> >
> > Br,
> > V
> > ------------------------------------------------------------------------
> >
> >
> ------------------------------------------------------------------------------
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>
>
> ------------------------------------------------------------------------------
> Download Intel&#174; Parallel Studio Eval
> Try the new software tools for yourself. Speed compiling, find bugs
> proactively, and fine-tune applications for parallel performance.
> See why Intel Parallel Studio got high marks during beta.
> http://p.sf.net/sfu/intel-sw-dev
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