[Bug 701202] New: gstplaysink badly initialized contrast/brightness

[GStreamer (bugzilla.gnome.org)]

https://bugzilla.gnome.org/show_bug.cgi?id=701202
  GStreamer | gst-plugins-base | 1.0.7

           Summary: gstplaysink badly initialized contrast/brightness
    Classification: Platform
           Product: GStreamer
           Version: 1.0.7
        OS/Version: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: Normal
         Component: gst-plugins-base
        AssignedTo: gstreamer-bugs at lists.freedesktop.org
        ReportedBy: dsd at laptop.org
         QAContact: gstreamer-bugs at lists.freedesktop.org
     GNOME version: ---


I am playing back a Theora video via xvimagesink with:
   gst-launch-1.0 playbin uri=file:///home/olpc/test.ogg

And it appears all-black on OLPC XO-1.5. This is a regression over
gstreamer-0.10. Here's what happens:

The underlying X11 graphics driver offers the XV_BRIGHTNESS attribute with
range 0 to 10000, default value 5000 (normal brightness). At the extremes,
value 0 is totally black (dark), value 10000 is totally white (bright). This
range and default value gets correctly communicated from the X server into the
color balance channel created by xvimagesink.

When the video is about to be played, in gstplaysink.c gen_video_chain() gets
called. This finds the colorbalance element of the xvimagesink and then calls
update_colorbalance().

update_colorbalance goes through all the channels, including brightness, and
sends values down to xvimagesink by calling gst_color_balance_set_value().

Which values does it use at this point? Well, values have not been set by any
user, so we are sending down the ones set in gst_play_sink_init():

  channel->label = g_strdup ("BRIGHTNESS");
  channel->min_value = -1000;
  channel->max_value = 1000;
  playsink->colorbalance_channels =
      g_list_append (playsink->colorbalance_channels, channel);
  playsink->colorbalance_values[1] = 0;

and we send that value *without any normalization* to what the proxy might
accept.

So xvimagesink receives a request to set brightness=0 (where the valid values
are from 0(dark) to 10000(bright)) which means "all black" and then it goes
ahead and plays back the video all black. :(

-- 
Configure bugmail: https://bugzilla.gnome.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the QA contact for the bug.
You are the assignee for the bug.