Commit graph

5 commits

Author SHA1 Message Date
Sebastian Dröge
aae25e0032 compositor: Implement different operators via per-pad property
This removes the crossfade-ratio property and replaces it with an
operator property. Currently this implements the following operators:

- SOURCE: Copy over the source and don't look at the destination
- OVER: Default blending of the source over the destination
- ADD: Like OVER but simply adding the alpha instead

See the example for how to implement crossfading with this.

https://bugzilla.gnome.org/show_bug.cgi?id=797169
2018-10-28 17:13:26 +00:00
Sebastian Dröge
b0ae6a5221 compositor: Use 255 as maximum alpha instead of 256
255 will easily become 0 in the blending function as they expect
the maximum value to be 255.

Can be reproduce with

gst-launch-1.0 videotestsrc pattern=ball ! c.sink_0 \
               videotestsrc pattern=snow ! c.sink_1 \
               compositor name=c \
                 sink_0::zorder=0 sink_1::zorder=1 sink_0::crossfade-ratio=0.5 \
                 background=black ! \
               videoconvert ! xvimagesink

crossfade-ratio +/- 0.001 makes it work correctly and the same happens
at e.g. 0.25, 0.75, N*0.0625

https://bugzilla.gnome.org/show_bug.cgi?id=796846
2018-07-23 18:59:33 +03:00
Thibault Saunier
806ff70590 compositor: Add support for crossfade blending
Crossfading is a bit more complex than just having two pads with the
right keyframes as the blending is not exactly the same.

The difference is in the way we compute the alpha channel, in the case
of crossfading, we have to compute an additive operation between
the destination and the source (factored by the alpha property of both
the input pad alpha property and the crossfading ratio) basically so
that the crossfade result of 2 opaque frames is also fully opaque at any
time in the crossfading process, avoid bleeding through the layer
blending.

Some rationnal can be found in https://phabricator.freedesktop.org/T7773.

https://bugzilla.gnome.org/show_bug.cgi?id=784827
2017-08-03 12:59:43 -04:00
Vincent Penquerc'h
15d51c1f6c compositor: fix illegal memory access in blend function with negative ypos
https://bugzilla.gnome.org/show_bug.cgi?id=741115
2015-01-19 12:38:13 +00:00
Mathieu Duponchelle
11fa711c34 compositor: Add a new compositor based on the new GstVideoAggregator base class
It is a replacement for videomixer with a similare API

Co-Authored by: Thibault Saunier <tsaunier@gnome.org>

https://bugzilla.gnome.org/show_bug.cgi?id=731919
2014-06-20 19:53:33 +02:00