[Trac #1334] xv intermittently loses display of gstreamer video

[Zarro Boogs per Child]

#1334: xv intermittently loses display of gstreamer video
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 Reporter:  erikb            |       Owner:  blizzard 
     Type:  defect           |      Status:  new      
 Priority:  high             |   Milestone:  Untriaged
Component:  camera-activity  |    Keywords:           
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 '''Problem:'''
 xvimagesink can disappear when showing gstreamer video.

 '''Hardware:'''
 Problem occurs on both the b1, b2 & ibm thinkpad fc6 boxes with gstreamer
 and xvimagesink.

 '''Description:'''
 A number of different ui actions can cause the display of gstreamer video,
 from any source (e.g., ogg theora playbin, videotestsrc, v42src) to
 disappear.  When the xvimagesink video disapears, it is still "there"
 according to ''xwininfo -tree'' queries.

 UI effects which can cause the disappearance include, but are not limited
 to:
  * changing the cursor appearance (e.g., default to wait)
  * hiding and showing the xvimagesink element (when it should be
 "visible", it sometimes opts not to appear).
  * on b1s and b2s, showing & hiding the task frame

 Video can be be made to re-appear by: moving an overlapping window or
 moving the containing frame of the xv sink.

 '''Notes:'''
 The problem is independent of v4l2 & cafe, as the same errant disappearing
 behavior can occur when using v4l2src & videotestsrc on both an XO and on
 an FC6 IBM thinkpad.  The problem probably lies somewhere in gstreamer's
 xvimagesink or in x itself.  A next step might be displaying video via xv
 using a framework other than gstreamer and applying the same ui tests
 above.

 The disappearing appears to be random.  There is no discernible pattern to
 what might cause the video to not appear on screen.  We suspect it is a
 timing issue.

 '''Files:'''
 Attached is a simple python script which toggles the cursor from default
 pointer to waiting causing gstreamer video in an xv sink to intermittently
 disappear.

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Ticket URL: <http://dev.laptop.org/ticket/1334>
One Laptop Per Child <http://laptop.org/>