Functions to create and handle overlay compositions on video buffers.
An overlay composition describes one or more overlay rectangles to be
blended on top of a video buffer.
This API serves two main purposes:
it can be used to attach overlay information (subtitles or logos)
to non-raw video buffers such as GL/VAAPI/VDPAU surfaces. The actual
blending of the overlay can then be done by e.g. the video sink that
processes these non-raw buffers.
it can also be used to blend overlay rectangles on top of raw video
buffers, thus consolidating blending functionality for raw video in
one place.
Together, this allows existing overlay elements to easily handle raw
and non-raw video as input in without major changes (once the overlays
have been put into a #GstVideoOverlayComposition object anyway) - for raw
video the overlay can just use the blending function to blend the data
on top of the video, and for surface buffers it can just attach them to
the buffer and let the sink render the overlays.
Functions to create and handle overlay compositions on video buffers.
An overlay composition describes one or more overlay rectangles to be blended on top of a video buffer.
This API serves two main purposes:
Together, this allows existing overlay elements to easily handle raw and non-raw video as input in without major changes (once the overlays have been put into a #GstVideoOverlayComposition object anyway) - for raw video the overlay can just use the blending function to blend the data on top of the video, and for surface buffers it can just attach them to the buffer and let the sink render the overlays.