[gstreamer-bugs] [Bug 537889] New: xvimagesink colorbalance is bad

[GStreamer (bugzilla.gnome.org)]

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  GStreamer | gst-plugins-base | Ver: HEAD CVS
           Summary: xvimagesink colorbalance is bad
           Product: GStreamer
           Version: HEAD CVS
          Platform: Other
        OS/Version: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: Normal
         Component: gst-plugins-base
        AssignedTo: gstreamer-bugs at lists.sourceforge.net
        ReportedBy: msmith at xiph.org
         QAContact: gstreamer-bugs at lists.sourceforge.net
     GNOME version: Unspecified
   GNOME milestone: Unspecified


xvimagesink implements colorbalance, to adjust various Xv attributes.

This has a number of problems:
 - internally, it (for no apparent reason!) scales the values. When scaling
back, this introduces rounding errors. 
 - it then sets the values on the xv port - but due to the rounding, they're
different from what they were previously. 
 - Some drivers (e.g. nvidia) treat these attributes as persistent - so the
rounding errors accumulate over time, until eventually video is unwatchable
(completely black).

Attached patch doesn't set the values unless they were changed through the
interface (fixes this problem for gst-launch, but not for totem)

This still doesn't fix it entirely with totem, for two reasons:
 - totem sets the values every time. We could fix that by not scaling things
(or by only scaling things for use via properties, not via the colourbalance
interface), but...
 - totem reads these via the colorbalance interface, and does its own scaling,
with rounding errors.

Probably the best answer is to add this patch, and then remove the colorbalance
stuff from totem (or at a minimum, stop setting values via that interface
unless the user changes something).


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