Running Android on a mainline graphics stack

My kernel knowledge is very inadequate to comment on potential APIs but, looking at various chipsets designed for STBs there were very power efficient hardware video mixers that did color conversion, scaling, and alpha blending (with limits). The idea was that a very slow CPU could offload video decoding (e.g. from the antenna or IP feed) to one block, render some simple UI onto a buffer and then blend those all together for free, every frame, perfectly. The video buffer was in YUV and the UI was in 565 RGB. There were also some specialized layers for subtitles and some other niche applications. Essentially each layer had some limited set of ways in which it could be used, with restrictions on buffer format, blending order etc.

The hardware I used to deal with ~15 years could handle one video and one bitmap layer. Later on we got more and more features, two video layers (one full features with better de-interlace and scaling features and one limited for picture-in-picture), additional layers arbitrary graphics for some nicer blending possibilities. All of this was on hardware that could not do any openGL.

Unfortunately none of that had sane drivers. At the time each vendor provided their own libraries to configure and use the video stack. Nowadays the problem is less visible because we get those speedy CPUs and even integrated graphics has a lot to offer but I suspect, if available and used correctly, we could save some power in idle-desktop / watching-video use cases.