No video playblack. Only audio.

Hello. I've just installed Windows 8.1 64bits and I can't play videos if I use EVR or EVR-CP, only audio and subtitles. Not 10bits, not 8 bits. Not mkv, not mp4. Not even avi.

I've tested this on the same machine:

VAIO E-series
ATI Radeon HD 5470 Mobility

Windows 7 32 bits: everything works
Windows 8 32 bits: everything works

Windows 7 and Windows 8 64 bits:

- EVR ----> only audio
- EVR-CP ----> only audio
- MADVR+DXVA2 (Native) ----> Audio+Video
- MADVR+DXVA2 (copy-back) ----> Doesn't work at all.

K-lite standard v11.0.05
Latest DirectX
Catalyst Drivers from the latest to older ones (I restored a saved image of my drive everytime)

I also tried VLC portable, and it works.

What problem could it be? Thank you.

You don't need to mess with drive images just to change a driver. Just uninstall the current driver, reboot, install other driver, reboot.

Does the problem also occur if you completely disable hardware acceleration? It seems to be a driver problem.

Post this info just in case, maybe I see something else wrong.
Codec Tweak Tool > Generate Log