<div dir="ltr">Hi Michael<div><br></div>I tried what you suggested and the callback is called only when I invoke GObject notify method. Nothing happens when the plugin updates the property. I will detail a little more my situation. I am the developer of this application <a href="https://github.com/wwmm/pulseeffects">https://github.com/wwmm/pulseeffects</a>. In it I use a few LADSPA and LV2 plugins that write on readonly parameters information like the current audio delay, attenuation or latency. I would like to show this kind of information without using a combination of GLib.timeout_add_seconds and get_property like I am doing know. Things like the delay of the delay plugin do not change all the time like the attenuation of a compressor. So it does not make sense to get this value in a timer.<div><br></div><div>Maybe there is a limitation in the LADSPA or LV2 support and there is no internal calling for the notify property when GStreamer updates the the readonly properties of these kind of plugins. Or maybe something is missing in the Python bindings.</div><div><br></div><div>Best regards,</div><div><br></div><div> Wellington<br><div><br></div></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Tue, Mar 20, 2018 at 1:05 PM, Michael Gruner <span dir="ltr"><<a href="mailto:michael.gruner@ridgerun.com" target="_blank">michael.gruner@ridgerun.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word;line-break:after-white-space">Hi Wellington<div><br></div><div>Every GObject (GstElements included) may emit a signal every time one of its properties change. This signal is named “notify::<property name>”. So, for example, if you’d like to register a callback every time the “sync” property changes, you would do something like:</div><div><br></div><div><i>/* Activate property change notification */<br>g_object_notify (G_OBJECT (<wbr>sink), “sync”);<br><br>/* Register a callback */<br>g_signal_connect (sink, "<wbr>notify::sync",<br> G_CALLBACK (sync_update_<wbr>callback), NULL);</i></div><div><br></div><div>You may find more info in the notify signal documentation:</div><div><a href="https://developer.gnome.org/gobject/stable/gobject-The-Base-Object-Type.html#GObject-notify" target="_blank">https://developer.gnome.org/<wbr>gobject/stable/gobject-The-<wbr>Base-Object-Type.html#GObject-<wbr>notify</a></div><div><br></div><div><br><div>
<div><div><font size="1">—</font></div><div><font size="1">Michael Gruner <<a href="mailto:michael.gruner@ridgerun.com" target="_blank">michael.gruner@ridgerun.com</a>></font></div><div><font size="1">Embedded Linux and GStreamer solutions</font></div><div><font size="1">RidgeRun Engineering</font></div><div><font size="1">Contact Us - <a href="http://www.ridgerun.com/#!contact/c3vn" target="_blank">http://www.ridgerun.com/#!<wbr>contact/c3vn</a></font></div></div>
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<div><br><blockquote type="cite"><div><div class="h5"><div>On Mar 20, 2018, at 09:18, wellington wallace <<a href="mailto:wellingtonwallace@gmail.com" target="_blank">wellingtonwallace@gmail.com</a>> wrote:</div><br class="m_1980810754508105088Apple-interchange-newline"></div></div><div><div><div class="h5"><div dir="ltr">Hi!<div><br></div><div>I would like to be notified when an readonly parameter changes. Consider for example the current delay or latency of ladspa or lv2 delay plugin. I tried the following with no success:</div><div><br></div><div><div>self.delay.bind_property('<wbr>left-delay', self.ui_value, 'value', GObject.BindingFlags.DEFAULT)</div><div><br></div><div>When the property is writable I am notified about its changes but not when it is readonly. I know that the plugin code made changes to the parameter because I can see them doing print(self.delay.get_property(<wbr>'left-delay)).</div><div><br></div><div>Is there a way to be notified about these changes without having to periodically calling get_property?</div><div><br></div><div>Best regards,</div><div><br></div><div> Wellington</div><div><br></div>-- <br><div class="m_1980810754508105088gmail_signature"><div dir="ltr">Prof.° Wellington Wallace Miguel Melo<br><br><div>CEFET/RJ Uned Nova Iguaçu<br><br></div></div></div>
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______________________________<wbr>_________________<br>gstreamer-devel mailing list<br><a href="mailto:gstreamer-devel@lists.freedesktop.org" target="_blank">gstreamer-devel@lists.<wbr>freedesktop.org</a><br><a href="https://lists.freedesktop.org/mailman/listinfo/gstreamer-devel" target="_blank">https://lists.freedesktop.org/<wbr>mailman/listinfo/gstreamer-<wbr>devel</a><br></div></blockquote></div><br></div></div></blockquote></div><br><br clear="all"><div><br></div>-- <br><div class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr">Prof.° Wellington Wallace Miguel Melo<br><br><div>CEFET/RJ Uned Nova Iguaçu<br><br></div></div></div>
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