the 'prefer-hardware' return unsupported

[yangfangfang1204]

hardDecode reportError:Unsupported configuration. Check isConfigSupported() prior to calling configure().,state:closed,frameRate:25

In WIN7 i5-7500 GTX1070 , i decode the 720P video by 'prefer-hardware ' , but it return unsupported .
When i set the 'prefer-software ', it could play ,but decoding performance is very poor.
So why the win7 could not decode by hard/GPU ?
chrome://gpu ,the result:
N1070-GPU.txt