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Hi Nicolas,</div>
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I've been working with Matthew on this project so I can expand a bit on the problem he's facing. We are using a custom GstContext with our pipeline, which is allocated and set by the application in response to the GST_MESSAGE_NEED_CONTEXT. At some point this
context can be marked as invalid, which can be achieved with the existing API by setting a new context with some fields in the underlying GstStructure set to null. We would then like the elements in the pipeline to request a new context from the application
by sending another GST_MESSAGE_NEED_CONTEXT, but this message is intercepted by GstBin, which simply sets the original context (<a href="https://github.com/GStreamer/gstreamer/blob/master/gst/gstbin.c#L3996" id="LPlnk">https://github.com/GStreamer/gstreamer/blob/master/gst/gstbin.c#L3996</a>).</div>
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It's not possible to pass a null pointer to gst_element_set_context() to "null out" an existing context, which would force GstBin to request a new one from the application.</div>
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It looks like we would need a new API, gst_element_remove_context(), in order to achieve what we want, unless we have missed something?</div>
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<br>
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Best regards</div>
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Tom</div>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> gstreamer-devel <gstreamer-devel-bounces@lists.freedesktop.org> on behalf of Nicolas Dufresne <nicolas@ndufresne.ca><br>
<b>Sent:</b> 06 April 2021 14:57<br>
<b>To:</b> Discussion of the development of and with GStreamer <gstreamer-devel@lists.freedesktop.org><br>
<b>Subject:</b> Re: Remove Context from Elements</font>
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<div class="PlainText">[External email]<br>
<br>
<br>
Le mardi 06 avril 2021 à 08:43 +0100, Matthew Walker a écrit :<br>
> Hi all,<br>
><br>
> I am working on an application which creates and utilises gstreamer pipelines.<br>
> One of the requirements is that the application must be able to erase the STC<br>
> context from the pipeline when stopping playback.<br>
><br>
> Currently I am using a function which resets the STC context on a given<br>
> element in conjunction with gst_iterator_foreach but I was wondering if there<br>
> was a better way to do this. Is there a gstreamer function which can remove<br>
> the STC context type from the context list of every element in a pipeline?<br>
<br>
All GstContext stored should be release when setting the pipeline to NULL state.<br>
If not, this is a bug.<br>
<br>
><br>
> Thanks for your help,<br>
> Matthew<br>
> _______________________________________________<br>
> gstreamer-devel mailing list<br>
> gstreamer-devel@lists.freedesktop.org<br>
> <a href="https://lists.freedesktop.org/mailman/listinfo/gstreamer-devel">https://lists.freedesktop.org/mailman/listinfo/gstreamer-devel</a><br>
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