Quote:
Originally Posted by
kraine 
And it's generate flickering so you better turn it off;
But it doesn't have to, if implemented correctly.
I drew up a little schematic of how I think DFI ('Dark Frame Insertion' or 'Film Projection' under 'MotionFlow') should work; here it is as a PDF:
http://cl.ly/MQB9
I believe the HW30/50 & VW95 are all using (2) in my schematic; namely, 96Hz processing with 48Hz flicker (frame doubling, then inserting a black frame between each frame).
Since VW1000 owners are indicating they
*don't* see any flicker with DFI on with 24p content, I'd assume the VW1000 is
at least using (3); namely 144Hz processing with 72Hz flicker (frame tripling, then inserting a black frame between each frame), if not higher.
72Hz flicker should not be objectionable. 48Hz flicker is. There are diminishing returns as you go to the higher frequency processing modes (4) & (5); in fact, they may be undesirable as asking the liquid crystal arrays to switch 240 times/sec is likely impractical.
144 times/sec (for 72Hz flicker) should not be impractical since apparently the HW50 can do 120 times/sec just fine, since that's what it needs to do for DFI with 60p content (which it handles just fine).
Note the cost in brightness for all the different modes should be the same, as I show in my schematics (total duration of dark frames remains the same; frequency increases and duration of each individual dark frame decreases).
However, there
is a way to implement some of those modes I outlined with
less of a loss in brightness, at the cost of more flicker. For example, in the 144Hz processing mode, you could handle the DFI in two different ways: one costs less brightness but causes flicker, while the other costs more brightness but reduces flicker:
144Hz Processing, frame-sextupling:
1-1-
D-1-1-
D | 2-2-
D-2-2-
D
----1/24s----
|----2/24s----
48Hz flicker, 2/6 frames are dark frames
... instead of:
1-
D-1-
D-1-
D | 2-
D-2-
D-2-
D
----1/24s----
|----2/24s----
72Hz flicker, every other frame is a dark frame
The first case only causes a 33% loss in brightness (2 out of every 6 frames is a dark frame); the latter causes 50% loss in brightness (every other frame is a dark frame).
So there are ways you could play with this algorithm to cause more/less drop in brightness. Given that the HW50 does not lose that much brightness when DFI is enabled, I wonder if they're using something more like the former. In the two schemes above, I would prefer the latter... less brightness, but no flicker.
Looks like Sony figured out DFI for 24p content on the VW1000. They're the only company that even uses DFI in a projector (that I know of) to achieve near-DLP motion (without soap opera effect). Not sure what's holding them back from proper implementation in all their other projectors.
Edited by sarangiman - 1/25/13 at 4:53pm
