[gst-devel] Plugin creation

Fri Mar 6 10:35:09 CET 2009

Just need to get the red_mask from the caps:

gst_filter_set_caps (GstPad * pad, GstCaps * caps)
{
  Gstmyvideo *filter;
  GstPad *otherpad;

  filter = GST_MYVIDEO (gst_pad_get_parent (pad));
  otherpad = (pad == filter->srcpad) ? filter->sinkpad : filter->srcpad;
  gst_object_unref (filter);

  GstStructure *structure = gst_caps_get_structure (caps, 0);
  ...
  gst_structure_get_int (structure, "red_mask", &filter->red_mask);
  ...
}

Then, in your process function, apply the mask to the samples, something
like this doed the trick:

...
guint samples = GST_BUFFER_SIZE (buf) / 2;
guint16 *data = (guint16 *) GST_BUFFER_DATA (buf);
gint i;

for (i=0; i<samples; i++) {
    data[i] = data[i] & filter->red_mask;
 }
...

I attach a silly filter plugin example that applies different color
masks to an rgb stream, hopefully you will find it useful.

Iago

El vie, 06-03-2009 a las 09:05 +0100, cammille at polytech.unice.fr
escribió:
> Nobody knows how to filter the red color ?
> 
> If someone can explain me how to manipulate the buffer just to keep the
> red color it would be great.
> 
> Thank you.
> 
> > Thanks everybody !
> >
> > I'm ok with you Albert, I think the simplest is RGB.. but there still is a
> > problem.
> > If I define a cap I have an error which is :
> > ERROR: from element /GstPipeline:pipeline0/GstV4l2Src:v4l2src0: Could not
> > negotiate format
> >
> > So I tried to force the format in the pipeline and I have the same error !
> >
> > here is my command : gst-launch
> > --gst-plugin-path=$HOME/gst-template/gst-plugin/src/.libs/ v4l2src  !
> > videoscale !  ffmpegcolorspace ! testfilter ! xvimagesink
> >
> > I have searched in vain other examples...
> >
> > It's strange, because in my code, if I change my buffer like that :
> > int i;
> > int size = GST_BUFFER_CAST(buf)->size;
> >
> > for(i=1; i < size; i++) {
> >   (buf->data)[i] = 0;
> > }
> >
> > The images become all green... I really don't understand why.
> >
> > I think there is a simple way to just keep the red color.. but I don't
> > find it.
> >
> >
> >
> >> Hi,
> >> the plugin name and description can (must...) be changed in the
> >> plugin_init function and GST_PLUGIN_DEFINE macro definition in the code
> >> that must be present in your code.
> >> Concerning the filtering itself, you must check that you have RGB (I
> >> guess
> >> that's the simplest) image buffers coming to your plugin in order to
> >> make
> >> your processing in the chain function. Best way would be to set the caps
> >> of your sink pad to video/x-rgb flow. Check other exisitng plugins to
> >> see
> >> how to do this. You'll need a ffmpegcolorspace element before your
> >> plugin
> >> to let the flow be in the good format.
> >> The example plugin is just a skeleton, you need now to specialize it
> >> with
> >> your own code... Read the gstreamer plugin writer's guide, it will give
> >> you information.
> >> Regards,
> >> Al
> >>
> >>
> >>
> >> ________________________________
> >> De : "cammille at polytech.unice.fr" <cammille at polytech.unice.fr>
> >> À : Discussion of the development of GStreamer
> >> <gstreamer-devel at lists.sourceforge.net>
> >> Envoyé le : Jeudi, 5 Mars 2009, 12h15mn 55s
> >> Objet : Re: [gst-devel] Plugin creation
> >>
> >> I found the problem ! The fact is that my plugin is not named
> >> "testfilter".. It's named "plugin". How can I change this name ?
> >> beacause
> >> I have never specified that my plugin is named "plugin".
> >>
> >> Another question, : now, I would like to create a simple plugin :
> >> I would like to filter the video taken by my webcam and filter the red
> >> color (i would like to apply an effect like the effectv plugin).
> >> I know the algorithm, but I'm not sure how to do that.
> >>
> >> Do you think I should create this plugin by using the example plugin ?
> >>
> >>
> >>> assuming that the shared library name is libgsttestfilters.so
> >>>
> >>> On Thu, Mar 5, 2009 at 4:28 PM, ved kpl <ved.kpl at gmail.com> wrote:
> >>>> Try gst-inspect on your plugin
> >>>>
> >>>> Assuming that the plugin is installed in
> >>>> "$HOME/gst-template/gst-plugin/src/.libs/"
> >>>> do the following and see what you get
> >>>>
> >>>>  gst-inspect
> >>>> $HOME/gst-template/gst-plugin/src/.libs/libgsttestfilters.so
> >>>>
> >>>> On Thu, Mar 5, 2009 at 4:15 PM,  <cammille at polytech.unice.fr> wrote:
> >>>>> Hello !
> >>>>> I would like to create a simple plugin such as effectv..
> >>>>>
> >>>>> But, first of all, I would like to create a "test plugin".
> >>>>> So, I tried to make the example described in the GStreamer Plugin
> >>>>> Writer's
> >>>>> Guide.
> >>>>>
> >>>>> I compiled the "test plugin" with the makefile, and now I'm trying to
> >>>>> launch this plugin, but I have an error..
> >>>>>
> >>>>> What's wrong with :
> >>>>>
> >>>>> $ gst-launch
> >>>>> --gst-plugin-path=$HOME/gst-template/gst-plugin/src/.libs/
> >>>>> fakesrc ! testfilters ! fakesink silent=TRUE
> >>>>>  > WARNING: erroneous pipeline: no element "testfilters"
> >>>>>
> >>>>> Maybe I have forgotten something ?
> >>>>>
> >>>>>
> >>>>> Thank you.
> >>>>>
> >>>>>
> >>>>>
> >>>>> ------------------------------------------------------------------------------
> >>>>> Open Source Business Conference (OSBC), March 24-25, 2009, San
> >>>>> Francisco, CA
> >>>>> -OSBC tackles the biggest issue in open source: Open Sourcing the
> >>>>> Enterprise
> >>>>> -Strategies to boost innovation and cut costs with open source
> >>>>> participation
> >>>>> -Receive a $600 discount off the registration fee with the source
> >>>>> code:
> >>>>> SFAD
> >>>>> http://p.sf.net/sfu/XcvMzF8H
> >>>>> _______________________________________________
> >>>>> gstreamer-devel mailing list
> >>>>> gstreamer-devel at lists.sourceforge.net
> >>>>> https://lists.sourceforge.net/lists/listinfo/gstreamer-devel
> >>>>>
> >>>>
> >>>
> >>> ------------------------------------------------------------------------------
> >>> Open Source Business Conference (OSBC), March 24-25, 2009, San
> >>> Francisco,
> >>> CA
> >>> -OSBC tackles the biggest issue in open source: Open Sourcing the
> >>> Enterprise
> >>> -Strategies to boost innovation and cut costs with open source
> >>> participation
> >>> -Receive a $600 discount off the registration fee with the source code:
> >>> SFAD
> >>> http://p.sf.net/sfu/XcvMzF8H
> >>> _______________________________________________
> >>> gstreamer-devel mailing list
> >>> gstreamer-devel at lists.sourceforge.net
> >>> https://lists.sourceforge.net/lists/listinfo/gstreamer-devel
> >>>
> >>
> >>
> >>
> >> ------------------------------------------------------------------------------
> >> Open Source Business Conference (OSBC), March 24-25, 2009, San
> >> Francisco,
> >> CA
> >> -OSBC tackles the biggest issue in open source: Open Sourcing the
> >> Enterprise
> >> -Strategies to boost innovation and cut costs with open source
> >> participation
> >> -Receive a $600 discount off the registration fee with the source code:
> >> SFAD
> >> http://p.sf.net/sfu/XcvMzF8H
> >> _______________________________________________
> >> gstreamer-devel mailing list
> >> gstreamer-devel at lists.sourceforge.net
> >> https://lists.sourceforge.net/lists/listinfo/gstreamer-devel
> >>
> >>
> >>
> >>       ------------------------------------------------------------------------------
> >> Open Source Business Conference (OSBC), March 24-25, 2009, San
> >> Francisco,
> >> CA
> >> -OSBC tackles the biggest issue in open source: Open Sourcing the
> >> Enterprise
> >> -Strategies to boost innovation and cut costs with open source
> >> participation
> >> -Receive a $600 discount off the registration fee with the source code:
> >> SFAD
> >> http://p.sf.net/sfu/XcvMzF8H_______________________________________________
> >> gstreamer-devel mailing list
> >> gstreamer-devel at lists.sourceforge.net
> >> https://lists.sourceforge.net/lists/listinfo/gstreamer-devel
> >>
> >
> >
> >
> > ------------------------------------------------------------------------------
> > Open Source Business Conference (OSBC), March 24-25, 2009, San Francisco,
> > CA
> > -OSBC tackles the biggest issue in open source: Open Sourcing the
> > Enterprise
> > -Strategies to boost innovation and cut costs with open source
> > participation
> > -Receive a $600 discount off the registration fee with the source code:
> > SFAD
> > http://p.sf.net/sfu/XcvMzF8H
> > _______________________________________________
> > gstreamer-devel mailing list
> > gstreamer-devel at lists.sourceforge.net
> > https://lists.sourceforge.net/lists/listinfo/gstreamer-devel
> >
> 
> 
> 
> ------------------------------------------------------------------------------
> Open Source Business Conference (OSBC), March 24-25, 2009, San Francisco, CA
> -OSBC tackles the biggest issue in open source: Open Sourcing the Enterprise
> -Strategies to boost innovation and cut costs with open source participation
> -Receive a $600 discount off the registration fee with the source code: SFAD
> http://p.sf.net/sfu/XcvMzF8H
> _______________________________________________
> gstreamer-devel mailing list
> gstreamer-devel at lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/gstreamer-devel
> 
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