[gst-devel] Plugin creation

Fri Mar 6 11:43:45 CET 2009

Thanks for your help !

I have another problem when I compile my project :  error:
gst/video/video.h: No such file or directory

So I can't test your code. I searched on google but it seems that nobody
have the problem.

Do you know how to resolve the problem ?

> (I sent another email with an implementation of a silly video filter
> that applies different color masks to an rgb stream, but for some reason
> it did not hit the list, guess it does not like attachments so I removed
> it, hopefully this one will make it. If you want the code, say so and
> I'll send it to you directly).
>
> In summary, you 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 does 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;
>  }
> ...
>
> Iago
>
> El vie, 06-03-2009 a las 09:05 +0100, cammille at polytech.unice.fr
> escribiÃ³:
>> 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>
>> >> Ã€ : Discussion of the development of GStreamer
>> >> <gstreamer-devel at lists.sourceforge.net>
>> >> EnvoyÃ© 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.
>> >>>>>
>> >>>>>
>> >>>>>
>> >>>>> ------------------------------------------------------------------------------
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>> >>> -Receive a $600 discount off the registration fee with the source
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>> >>
>> >>
>> >>
>> >> ------------------------------------------------------------------------------
>> >> 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
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>> >>
>> >>
>> >>       ------------------------------------------------------------------------------
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>> >> 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:
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>> >> http://p.sf.net/sfu/XcvMzF8H_______________________________________________
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>> >>
>> >
>> >
>> >
>> > ------------------------------------------------------------------------------
>> > 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:
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>> > http://p.sf.net/sfu/XcvMzF8H
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>> >
>>
>>
>>
>> ------------------------------------------------------------------------------
>> 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
>> _______________________________________________
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>> 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
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