https://bugs.freedesktop.org/show_bug.cgi?id=71448
--- Comment #19 from darkbasic darkbasic@linuxsystems.it --- Alex from the tests I did 3.13 doesn't seem to behave the way you described.
With power state set to "high", desktop effect OFF and no glxgears: MPEG DECODING (1920x1080): 5 frames/s MPEG DECODING (1280x720): 21 frames/s H264 DECODING (1920x1080): 8 frames/s H264 DECODING (1280x720): 5 frames/s
With power state set to "high", desktop effect OFF and glxgears: MPEG DECODING (1920x1080): 77 frames/s MPEG DECODING (1280x720): 117 frames/s H264 DECODING (1920x1080): 16 frames/s H264 DECODING (1280x720): 91 frames/s
With power state set to "high", desktop effect ON and glxgears: MPEG DECODING (1920x1080): 77 frames/s MPEG DECODING (1280x720): 117 frames/s H264 DECODING (1920x1080): 51 frames/s H264 DECODING (1280x720): 91 frames/s
It seems even glxgears wasn't able to keep highest power state in all tests: enabling desktop effects was enough to keep higher state in the second-last test.
What do you mean by "plain video playback"? If you mean without using vdpau it works flawlessly.