libavcodec's nvdec wrapper can return invalid frames, that do not have
any data fields set. This is not allowed by the API, but why would they
follow their own API?
Add a workaround to specifically detect this situation. In practice,
this should fall back to software decoding if it happens too often in a
row. (But single errors are still tolerated, because I don't know why.)
Untested due to lack of hardware from the regrettable graphics company.
Better do this here than deal with the moronic project we unfortunately
depend on.
See: #7185
wm4
bd96b97170