[gst-devel] GStreamer Graph File Storage

David Schleef ds at schleef.org
Mon Aug 7 22:31:25 CEST 2006

On Mon, Aug 07, 2006 at 12:49:17PM -0400, Brendan Howell wrote:
> Hey All,
>   For those who don't recall, I'm the google SoC guy who's working on
> the GStreamer Graphical Pipeline Editor.  
> In any case, Edward suggested that I start a conversation on the dev
> list about some sort of format for storing descriptions (or persistent
> objects) of GStreamer pipelines.  I know 0.8 had an XML save/restore
> capability.  The pipeline editor would really benefit from this feature
> and I'm sure a lot of other apps would like a nice way to save and
> restore gstreamer state.
> Here are some questions that I have at least:
> - Can someone give a reference or short recap on why this can't/won't
> work in 0.10?  

The main problem is that not all object properties should be saved to/
restored from the XML file, and that it's not clear which properties
should be saved.  As a first approximation of what should be done, the
various properties of each element need to be tagged as to "metadata"
(like GstElement.name), true "element parameters"
(GstVideoscale.method which affect how the element behaves w.r.t the
pipeline data), and "random crap" (like GstIdentity.signal-handoffs)
that affect how the element interfaces with the application.
Fortunately, most of the random crap is read-only, which obviously
doesn't need to be saved or restored.

> - What about just spitting out a gst-inspect string?  What are the
> limitations there?

Er, you mean gst-launch string?  I think that's a good idea, although
it can't express the full range of possible pipelines.  Another idea
would be to export to a python script.


David Schleef
Big Kitten LLC (http://www.bigkitten.com/) -- data acquisition on Linux

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