[gst-devel] dynamic overlaying of images on video
gneuez at hotmail.com
Wed Aug 29 22:01:06 CEST 2007
>From: Tim Müller <t.i.m at zen.co.uk>
>To: gstreamer-devel at lists.sourceforge.net
>Subject: Re: [gst-devel] dynamic overlaying of images on video
>Date: Wed, 29 Aug 2007 13:47:39 +0100
> > My problem is that the position of each overlay sink pad is fixed to
> > so all layers overlap each-others. I have modified the component such
> > each pad has a fixed (hardcoded) position in the output frame. But this
> > static, not dynamic...
>The videomixer sink pads all have "xpos", "ypos", "zorder" and "alpha"
>properties (which you can set in your code using g_object_set()). The
>documentation should probably mention that somewhere.
Yes, I've seen that in the code source of videomixer. But these properties
are not seen as the plugin ones (using gst-inspect for example), these are
pads properties. From my application code, how should I access to them? Pads
are generated with random names when I link a new 'image pipeline' to it, so
unless I access the GList of sinks and try to use g_object_set() on parsed
list elements, I don't get right how to set these properties...
> > I was thinking of deriving the videomixer element, adding an additional
> > sink pad. This pad would be fed with a txt file giving the (x,y) pos for
> > each image to be overlaid.
> > In fact, I'd also like to extend this to the pango textoverlay (for
> > displaying the name of the player below its thumbnail in the video, I
> > need to specify the position where the text must be set).
> > Would that make sense to you, or is there any better/nicer solution? Has
> > anyone experienced that kind of problem?
>There's also the textrender element which renders a text string to a
>bitmap, which you could then in turn feed into videomixer. Or you could
>just put N textoverlay elements in a row after the videomixer, rendering
>the texts (settable via the "text" property) at whatever position you
Yes, I would try that, as soon as I can figure out the solution of the x/y
I have another question relative to the text renderer. If I launch
"gst-launch filesrc location=sampletext.txt ! textrender ! videomixer
name=mix ! directdrawsink videotestsrc ! mix.", with the text file
containing a single text line, this text is displayed on the video only for
a few secs, then disappears. Is there a way to have it displayed
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