RFC: entatransform plugin

Submitted by Michael Tretter @m.tretter

Link to original bug (#774991)

Description

Vivante 2D GPUs feature a video rasterizer that is able to scale frames or to transform frames between certain pixel formats using a filter kernel.

The created the etnatransform plugin, which allows to use the video rasterizer via the etnaviv driver in Gstreamer pipelines.

The current plugin basically consists of code that was copied together from the xf86-video-armada driver (filter kernel) and the etnaviv tests in libdrm and repackaged to be usable as a Gstreamer plugin. It is not really well tested, would benefit a lot from some refactoring and modularization, and contains some crude workarounds.

It is not ready for inclusion in Gstreamer, but maybe someone finds use for it.