Not sure if this is an OpenELEC issue, TVHeadend or XBMC but I get video corruption when enabling Hardware acceleration on Live TV in all recent builds.
Debug log here
http://xbmclogs.com/show.php?id=189792
I think the errors are here:
18:04:33 T:139971960755968 ERROR: ffmpeg[C2FFD700]: [h264] mmco: unref short failure
18:04:33 T:139971960755968 ERROR: Previous line repeats 1 times.
18:04:33 T:139971960755968 DEBUG: CDVDPlayerVideo::CalcDropRequirement - hurry: 0
18:04:33 T:139971960755968 DEBUG: ffmpeg[C2FFD700]: [h264] Increasing reorder buffer to 1
18:04:33 T:139971960755968 DEBUG: CDVDPlayerVideo::CalcDropRequirement - hurry: 0
18:04:33 T:139971960755968 DEBUG: ffmpeg[C2FFD700]: [h264] Increasing reorder buffer to 2
18:04:33 T:139971960755968 DEBUG: CDVDPlayerVideo::CalcDropRequirement - hurry: 0
18:04:33 T:139971960755968 DEBUG: ffmpeg[C2FFD700]: [h264] Increasing reorder buffer to 3
18:04:33 T:139971960755968 DEBUG: CDVDPlayerVideo::CalcDropRequirement - hurry: 0
18:04:33 T:139971960755968 DEBUG: Previous line repeats 4 times.
18:04:33 T:139971960755968 ERROR: ffmpeg[C2FFD700]: [h264] mmco: unref short failure
18:04:33 T:139971960755968 DEBUG: CDVDPlayerVideo::CalcDropRequirement - hurry: 0
18:04:34 T:139971960755968 DEBUG: Previous line repeats 5 times.
18:04:34 T:139971960755968 NOTICE: fps: 25.000000, pwidth: 1920, pheight: 1080, dwidth: 1920, dheight: 1080
18:04:34 T:139971960755968 DEBUG: OutputPicture - change configuration. 1920x1080. framerate: 25.00. format: NV12
18:04:34 T:139971960755968 NOTICE: Display resolution ADJUST : HDMI1: 1920x1080 @ 50.00Hz (19) (weight: 0.000)
Turning off Hardware accelration for video seems to fix it but I get very high CPU load on my NUC i3