[mythtv-users] 1080p choppy playback

Yeechang Lee ylee at pobox.com
Sat Jan 12 04:22:38 UTC 2008

Andrew Gallatin <gallatin at cs.duke.edu> says:
> I thought the problems with Bob were only present when running a
> display at 1080i, not 1080p.  Bob seems to work for me with my 5200 at
> 1080p.

Unless your 5200 is capable of a 60Hz refresh rate at 1920x1080--a
possibility I can't dismiss--Bob won't be effective, and you haven't
seen just how jaw droppingly-smooth its output can look on a CRT or a
1080p-capable flat panel.

Here is my modeline:

ModeLine     "1920x1080-mine" 148.35
	      1920 1960 2016 2200
	      1080 1082 1088 1125

My 6200, with this modeline, outputs over DVI very nice
59.94Hz-refresh 1920x1080 video to my 47" 1080p-capable flat
panel. Mythfrontend is happy because of a refresh rate of 16683,
exactly half (or less) of the 33366 frame interval. This, in turn,
permits Bob to work, because Bob doubles the frame rate on 24/30Hz
interlaced content.

My 5300 (a PCI Express-compatible 5200) can't handle this modeline,
because the dot clock, 148.35MHz, is too high. It *can* handle lower
values. If I pass it the same mode rate but with a dot clock half this
value--74.175MHz--then the card puts out 29.97Hz 1920x1080
video. Again, no problem for the panel, but Bob doesn't work because
it can't increase the frame rate on interlaced content.

Frontend/backend:	P4 3.0GHz, 1.5TB software RAID 5 array
Slave backend:		Quad-core Xeon 1.6GHz, 6.6TB sw RAID 6
Video inputs:		Four high-definition over FireWire/OTA
Accessories:		47" 1080p LCD, 5.1 digital, and MX-600

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