[Bug 708882] New: Unintended behaviour with text overlay and alpha buffers.

[GStreamer (bugzilla.gnome.org)]

https://bugzilla.gnome.org/show_bug.cgi?id=708882
  GStreamer | gst-plugins-base | git

           Summary: Unintended behaviour with text overlay and alpha
                    buffers.
    Classification: Platform
           Product: GStreamer
           Version: git
        OS/Version: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: Normal
         Component: gst-plugins-base
        AssignedTo: gstreamer-bugs at lists.freedesktop.org
        ReportedBy: mathieu.duponchelle at epitech.eu
         QAContact: gstreamer-bugs at lists.freedesktop.org
     GNOME version: ---


Created an attachment (id=255889)
 View: https://bugzilla.gnome.org/attachment.cgi?id=255889
 Review: https://bugzilla.gnome.org/review?bug=708882&attachment=255889

fixes the reported issue

I'm not sure this can be considered as a bug, but it sure gets in the way:

gst-launch-1.0 videotestsrc pattern=17 foreground-color=0x00000000 !
video/x-raw, format=ARGB ! textoverlay text="Should have 255 as alpha" !
videomixer name=m sink_0::zorder=0 sink_1::zorder=1 ! videoconvert !
video/x-raw, format=I420 ! xvimagesink videotestsrc ! m.

Doing so, I would expect the text to still appear, as the color property in
textoverlay has its alpha byte at 0xFF, even if the buffers output by
videotestsrc have an alpha byte at 0x00.

May'be the bug is in basetextoverlay, but I have a patch in video-blend that
yields the intended behaviour, really not sure it is correct but I'll attach it
for reference.

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