How to refresh video window when no frame has been received from udpsrc

[Edward Hervey]

Hi,

On Mon, 2012-11-26 at 15:24 -0600, Tara.Hemphill at l-3com.com wrote:
> Gstreamer version: 0.10.35
> 
>  
> 
> I have a pipeline such as:  gst-launch udpsrc
> uri=udp://239.255.0.1:11111 ! decodebin ! dshowvideosink ...
> 
>  
> 
> However, when nothing is coming in on the UDP stream, resizing the
> video window causes the blank video panel to become jumbled and messed
> up since there is no frame to refresh it.  I am currently setting the
> window handle to a specific GDK_WINDOW_XWINDOW upon receiving the
> “prepare-xwindow-id” GstMessage.  I am handling the Expose events in
> the GST_STATE_PAUSED state (as advised here:
> http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base-libs/html/gst-plugins-base-libs-gstvideooverlay.html#GstVideoOverlay), but there is no “last frame” to redraw yet.  Is there a standard way to work around this issue?

  If there is no last-frame, it's up to the implementation (i.e.
dshowvideosink in this case) to figure out what to do when you get new
exposes.
  A black frame seems like the sensible thing to do. If dshow has some
API to easily do that in one call you could implement that. Otherwise
you might have to create a "fake" black frame and use that until you get
a real upstream video frame.

  Maybe it's something we should add in the base video sink classes,
seems like a common feature to handle.

   Edward

> 
>  
> 
> Thanks,
> 
>  
> 
> Tara Hemphill
> 
> Software Engineer
> 
> L-3 Communications - IS
> 
> x3012
> 
>  
> 
> 
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