Re: [gst-devel] video analysis tool

[alberto c. <al...@gm...>]

Fàbio,

I keep having more problems than solutions...

I've done my GstKuTest plugin (attached), using element_make from
gst-plugin-template, registered it statically, but
gst_element_factory("kutest", "my_test") returns NULL.

As if it was not enough, I can't get the video-sink:

     GstElement *videosink;
     g_object_get(G_OBJECT(play), "video-sink", &videosink, NULL);

videosink will always be NULL, no matter the state of play (which is my
playbin).

As an aside, I'm not receiving GST_MESSAGE_DURATION, but I solvedby
querying the duration when the pipeline goes into PAUSED state. 

Can you, or anyone else, help me out?
Thank you very very much
alb

On Wed, 2006-08-23 at 15:50 -0300, Fábio Sato wrote:
> Alberto,
> 
> I'm also using gstreamer to develop some computer vision routines and
> my approach is to develop one plugin for each algorithm that I need:
> background subtraction, edge detection, convolution, morphological
> operators, etc. 
> 
> This way I can easily prototype an application using gst-launch and
> test my plugins.
> 
> To create these plugins I've just followed the effectv plugins
> examples (gst-plugins-good).
> 
> ---
> Fábio Sato
> 
> 
> 2006/8/23, alberto colombo <al...@gm...>:
>         hello
>         
>         I'm working on a computer vision project and I need to build a
>         video
>         analysis tool. For the moment, I will have to to a simple
>         mean-shift
>         tracker, however it's going to expand a lot.
>         
>         Anyway, I decided to use gstreamer (both because it looks the
>         right tool 
>         and because I was advised so by people from vlc-devel!).
>         Basically, what
>         I need to do is open an avi or mpeg file (for now, but
>         possibly a live
>         stream in the future), step through each frame, do my analysis
>         on the 
>         image and paint the output over the frame.
>         
>         My first attempt was to use playbin to do all the dirty stuff,
>         and then
>         send "seek" events to step frame by frame:
>         
>         void MainWindow::on_button_next_frame_clicked() 
>         {
>             ...
>             gst_element_seek(play, 1.0, GST_FORMAT_DEFAULT,
>                          GstSeekFlags(GST_SEEK_FLAG_FLUSH|
>         GST_SEEK_FLAG_ACCURATE),
>                          GST_SEEK_TYPE_SET, pos+1,
>                          GST_SEEK_TYPE_NONE, -1 ); 
>         }
>         
>         However, this code doesn't work: the video position does not
>         change. So
>         I tried with
>         
>         void MainWindow::on_button_next_frame_clicked()
>         {
>             ...
>             gst_element_seek(play, 1.0, GST_FORMAT_TIME, 
>                              GstSeekFlags(GST_SEEK_FLAG_FLUSH|
>         GST_SEEK_FLAG_ACCURATE),
>                              GST_SEEK_TYPE_SET, pos+1000*1000*1000/25,
>                              GST_SEEK_TYPE_NONE, -1 );
>         }
>         
>         But it seeks too fast: every click advances by about 1/12
>         seconds, 
>         instead of 1/25. (By the way, doing a non-flushing seek hangs
>         the
>         application, looks like a deadlock because the CPU is 0%).
>         
>         Can anyone explain why? Most important, is this the right
>         approach to
>         the problem, or shall I write a plugin and put it somewhere
>         between the 
>         decoding and the displaying elements?
>         
>         Thank you very much
>         alberto
>         --
>         ICQ#: 319420338
>         
>         
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> -- 
> Fábio Sato 
> -------------------------------------------------------------------------
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