GameLifter wrote: ↑11 Feb 2020, 23:54
The new LG OLED TV's set to release this year are going to get a 120Hz BFI mode and I've seen people on other forums who are really looking forward to this feature. I've been wondering how this method of eliminating motion blur might compare to the others out there and if it could be viable for both 60Hz and 120Hz content.
OLED BFI is excellent, the question is how big the pulse width is.
alapsu wrote: ↑17 Feb 2020, 19:34
So if it takes 10 ms for the screen to change all its pixels from black to something else to display a frame, and at 120 Hz a new frame is shown every 8.33 ms, that's a problem for 120 Hz BFI. I
think the problem is essentially that the duration of the black frame is limited so that a new frame can be displayed at the start of the next cycle, a.k.a. you end up with high persistence. The lower the persistence, less perceived motion blur, meaning essentially that you want a relatively high ratio of black screen to lit screen.
(again, please correct me)
Giving you a correction.
It doesn't work exactly like that.
Those familiar with high speed videos of LCD / OLED refresh,
www.blurbusters.com/scanout -- will better understand this reply, so once you've seen those high speed videos, you'll better understand the below:
Black frame insertion (BFI) doesn't have to be monolithic when using an independent OFF scanout pass at a custom temporal offset.
For example, it can be:
Or it could be:
The Sony TriMaster used BFI at a 7.5ms:16.7ms ratio, in a rolling-window scan.
There are scan patterns that can be engineered.
Also, it's possible to have a higher refresh rate with a slowscan, e.g. 120Hz refresh rate out of 60Hz-velocity scanout, if you use two different scanwindows:
Lessons:
- Not all pixels refresh simultaneously. They 'scan' from top to bottom on most display panels
- BFI doesn't have to be integer divisors (in other words, custom BFI pulse ratios are possible)
- Refresh rate doesn't have to determine scanout velocity (if using creative engineering)
- It's possible to concurrently-scan if the panel is designed as such (but
should use anti-sawtooth-artifact technique)
Related thread:
OLED Rolling Scan Patterns
Including a possible scan-pattern path to doing 960 Hz refresh on an OLED.
It may just be better to refresh 8-pixel-rows simultaneously in blocks at a time (ultra-fast scanout), but either way, that's a microwire engineering nightmare at this stage.
The point is, you can create really insane refresh rates out of really low scan velocities taking longer than a refresh cycle, via an advanced concurrent-scan algorithm (and eliminate sawtooth artifacts by permanently assigning one unbroken framebuffer per separate unique scanout sweep, which will require framebuffering 8 refresh cycles off the wire (DisplayPort), to do an 8-concurrent scanout)
Somebody needs to point a 960fps camera at the LG 120Hz OLED displaying
www.testufo.com/scanout and post it on YouTube or here for us. I can easily tell you how its BFI works simply by staring at these high speed videos.