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 <div>2006/8/23, alberto colombo <<a href="mailto:albx79@gmail.com">albx79@gmail.com</a>>:<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"> 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 ------------------------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo <a href="http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642"> http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642</a> _______________________________________________ gstreamer-devel mailing list <a href="mailto:gstreamer-devel@lists.sourceforge.net"> gstreamer-devel@lists.sourceforge.net</a> <a href="https://lists.sourceforge.net/lists/listinfo/gstreamer-devel">https://lists.sourceforge.net/lists/listinfo/gstreamer-devel</a> </blockquote></div> -- Fábio Sato