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>
When a pad has alpha != 1.0 it means that the resulting frames will
contain alpha and thus can't fully obscure with a lower zorder.
Also simplifies the other checks as blending with an OVER or on a
transparent is not a no-op as previously assumed.
Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-base/-/merge_requests/764>
The blend functions for alpha formats need to do more work than just
doing a memcpy, so we can do a memcpy when we know that a blend is not
actually needed.
1080p AYUV ! compositor background=transparent ! fakesink - 56% faster
Specifically, when we don't draw the background and the first pad we
draw completely covers the output frame, we can just copy it as-is.
The rest of the pads (if any) will get composited on top normally.
If the background is transparent and obscured by a pad that may or may
not have alpha, we can still skip drawing it entirely
AYUV 1080p ! compositor background=transparent ! fakesink - 75% faster
We don't need to waste time drawing the background when one of the
pads completely covers the output and there's no alpha on the pad or
in the video format. Speedups:
I420 1080p ! compositor ! fakesink - 72% faster
I420 1080p ! compositor background=black ! fakesink - 45% faster
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
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
This moves all the conversion related code to a single place, allows
less code-duplication inside compositor and makes the glmixer code less
awkward. It's also the same pattern as used by GstAudioAggregator.
The aggregated_frame is now called prepared_frame and passed to the
prepare_frame and cleanup_frame virtual methods directly. For the
currently queued buffer there is a method on the video aggregator pad
now.
