[gst-devel] video analysis tool

[Fábio Sato]

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 <albx79 at gmail.com>:
>
> 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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