Adding new property for user to be able to set expected the maximum
number of blend task threads. This can be useful in case that user
wants to restrict the number of parallel task runners for system
resource management or debugging/development purpose.
Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-base/-/merge_requests/1242>
Improves throughput of the total convert and blend process and allows
for higher performance across slightly more threads.
Also make use of video aggregator's task pool for blending as well in
order to reduce the number of threads.
Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-base/-/merge_requests/1129>
When that property is left to its default, the width and height
property considers frames from input pads with width or height <= 0
should be left unscaled in that dimension.
Setting this property to FALSE changes that behaviour to < 0, as when
animating these properties, 0 should be a valid end value (eg. shrinking
an input stream until it disappears).
The default value of the width and height properties is set to -1, so that
the default behaviour stays consistent whether that new property is set
or not.
Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-base/-/merge_requests/923>
Increases the throughput of compositing by using more CPU cycles across
multiple threads. Simple cases (the output contains one pixel from at
most one input) can have up to a 70% increase in throughput. Not so
simple cases are limited by the region with the most number of
composite operations.
Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-base/-/merge_requests/755>
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
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
