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Bug 708882 - Unintended behaviour with text overlay and alpha buffers.
Unintended behaviour with text overlay and alpha buffers.
Status: RESOLVED DUPLICATE of bug 681447
Product: GStreamer
Classification: Platform
Component: gst-plugins-base
git master
Other Linux
: Normal normal
: git master
Assigned To: GStreamer Maintainers
GStreamer Maintainers
Depends on:
Blocks:
 
 
Reported: 2013-09-26 23:14 UTC by Mathieu Duponchelle
Modified: 2015-10-22 09:40 UTC
See Also:
GNOME target: ---
GNOME version: ---

Attachments
fixes the reported issue (966 bytes, patch)
2013-09-26 23:14 UTC, Mathieu Duponchelle 		accepted-commit_now Details | Review

Description Mathieu Duponchelle 2013-09-26 23:14:01 UTC 
Created attachment 255889 [details] [review]
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.
Comment 1 Thibault Saunier 2013-10-30 15:47:07 UTC 

*** This bug has been marked as a duplicate of bug 681447 ***
Comment 2 Thibault Saunier 2015-10-22 09:14:51 UTC 
Review of attachment 255889 [details] [review]:

Looks good to me.
Comment 3 Thibault Saunier 2015-10-22 09:40:41 UTC 
(In reply to Thibault Saunier from comment #2)
> Review of attachment 255889 [details] [review] [review]:
> 
> Looks good to me.

Actually it is not, in case of a not fully transparent background it will make the background fully transparent where we are blending the text.