Finally, and somewhat paradoxically, Maxwell 2 inherits Kepler and Maxwell 1’s hybrid HEVC decode support. First introduced with Maxwell 1 and backported to Kepler, NVIDIA’s hybrid HEVC decode support enables HEVC decoding on these parts by using a combination of software (shader) and hardware decoding, leveraging the reusable portions of the H.264 decode block to offload to fixed function hardware what elements it can, and processing the rest in software.
A hybrid decode process is not going to be as power efficient as a full fixed function decoder, but handled in the GPU it will be much faster and more power efficient than handling the process in software. The fact that Maxwell 2 gets a hardware HEVC encoder but a hybrid HEVC decoder is in turn a result of the realities of hardware development for NVIDIA; you can’t hybridize encoding, and the hybrid decode process is good enough for now. So NVIDIA spent their efforts on getting hardware HEVC encoding going first, and at this point we’d expect to see full hardware HEVC decoding show up in a future generation of hardware (and we’d note that NVIDIA can swap VP blocks at will, so it doesn’t necessarily have to be Pascal).