extreme gpu memory allocation with player set to mpv & hardware accel set to auto

[rakslice]

I notice that with the player set to "mpv" and hardware accel set to "auto" in Orion's settings, the "Dedicated GPU Memory" metric for the orion.exe process indicates it is allocating GPU memory like crazy increasing at about 100 mb/sec, while video is playing.

With player set to mpv, changing the hardware accel setting to any choice in the pulldown other than auto (i.e. dxva2-copy, d3d11va-copy, cuda-copy, nvdec-copy, or no) stops this behaviour, as does changing the player to QtAV.

I'm running the most recent x64 Appveyor build from https://ci.appveyor.com/project/alamminsalo/orion/branch/master, in Windows 10 Pro x64 1909, with a GTX 1070 with the current 445.87 driver.

[rakslice]

The allocated memory must never be meaningfully used, as the number goes far too high for there to be physical GPU memory to back it.