adaptive frame rate output
Matthew Phillips
Member Posts: 45 ✭
in Support
Will YouView boxes eventually feature adaptive frame rate output - as I understand it we are currently locked at 50hz causing judder issues with streaming services such as Netflix and it's particularly problematic with Amazon Prime which features quite a lot of content at various frame rates including some standard definition NTSC (american tv shows in sd for example) which is already displaying pulldown before being forced out at 50hz which then causes a second layer of frame dropping resulting in a very jerky picture. I've been reading about other streaming hardware that does feature adaptive frame rate that detects the native framerate of any video feed and adjusts the output accordingly - this is really the ultimate for streaming and it would be great if YouView could get on board with something like this.
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But to answer your question the answer is 'no' YouView won't, sorry.
So if you want 60hz Netflix / Amazon with a compatible adaptive 60hz TV, you'll have to use another device. But in the UK there aren't many.
Feedback has been passed onto Youview about this issue, and they’re aware of it. Beyond that we don’t know what YouView’s plans are for variable frame rates.
I think for the long term sustainability of the platform, and to promote Youview as a premier destination for streaming services, it would be sensible to invest in developing a feature to accommodate this.
It’s a feature that’s becoming much more common on other platforms now. In fact I’m considering buying a device that can do adaptive frame rates.
"It’s a feature that’s becoming much more common on other platforms now."
On which other recordable boxes is this feature available Joe?
What it doesn’t do well is YouView’s workaround for Netflix’s mostly 60hz content, which has the annoying repetitive judder on panning shots.
I have a nowtv box with new Netflix app, which seems to play content without these issues. Though I haven’t used it extensively yet. I presume it’s stuck at 60hz, so maybe UK material may be worse on that device?
So presumably, your ex cathedra pronouncement about what YouView will and won’t do in this area is based on publicly available information, as you would surely not break an NDA, or even just make it up?
So can you please share a link with us, as you did before about Amazon Prime on BT TV 4K boxes? Even if what you link to has doubts cast on its reliability, as happened there?
I am not worried about believing it or not; you may well be right, but I don’t believe that you know you are right.
But there are those in the Community - including me - who give much weight to what you say, and often very well-deserved weight; I would suggest you have a duty to us all to distinguish known fact from mere supposition.
" I would suggest you have a duty to us all to distinguish known fact from mere supposition."
I agree and will scale back what I say about future changes and hardware.
The only known is that they are coming.
Fixed rate but adaptive switching can be can be done by most TVs these days. The TV switches to 24/50/60 (or a multiple of) fps to match the incoming fixed signal. Usually there is a momentary blank as the HDMI system resyncs. There isn’t usually a blank for frame rate changes within the TVs own apps (my LG OLED and Netflix for example doesn’t blank with frame rate changes).
The sticking block to date has been that set top streaming boxes have had fixed HDMI outputs. This is now changing. Apple TV 4K was the first. Now Fire TV and Roku support it.
Sky Q now has a “reduce judder” setting which is just frame rate adjustment for internal apps - notably Netflix now it has launched.
it seems likely Youview will support it for Netflix and Amazon if the hardware is capable.
Hopefully they can do proper frame rate adapting on a per source basis.
The downside of switching to 24P is that the overlay UI gets very jerky because of the low frame rate.
My LG TV gets around this by sticking at 120Hz for 24P and 60P internal sources and doing a 5:1 or 2:1 pull down for each. So you get no judder and the UI remains smooth. Hence I usually use the TV for Netflix and Amazon rather than a set top box.
Amazon Fire Frame Rate Matching - if amazon can do it YouView can do it.
But please, no posts of 'ehhh, I remember the days when...' But I doubt the old favourites could have done this. But what about other current recordable TV boxes? Which are SKY and Virgin Media? Can they?
If the TV does drop to 24fps screen refresh rate then that can look flickery as such a low refresh rate is below the flicker detection threshold of most individuals.
Interestingly for that reason cinemas don't really display at 24fps they display at 48fps or even 72fps but repeat the same frame twice or 3 times - the 48/72Hz gate closure is thereby rendered imperceptible. There is a section on this on Wikipedia.
3.1.4 Film gate and frame advance
24fps is also very jerky for a settop box UI. That's why Apple TV4K's UI looks very flickery in fixed 24P mode. Most people set the UI to 50/60Hz and switch to 24P only with full screen videos. Unfortunately set top boxes that use picture in picture (Sky for example) would have a terrible time finding a workable solution.
Another problem is that the "info" button on most TVs don't tell you what the screen refresh rate is - they tell you the input source details. The TV can still be running a higher and/or non-integer multiple screen refresh rate. It is almost certainly running a higher refresh rate if motion blur correction system are turned on as these use frame interpolation which requires the use of in-between frames.
LCD can "dim" between frames, however, if black frame insertion (BFI) is used as the motion blur correction technology and flicker could then be noticeable - however as I said motion blur correction usually only is done at high refresh rates such as 120Hz. OLED and plasma "pixels" do dim because they are turned on and off independently and there is no backlight so can still flicker at low refresh rates.
So how your TV displays adaptive refresh rate switching is dependant upon how the TV manufacturer has designed the panel and electronics and what motion blur technique is being used. My 2018 LG OLED stays at 120Hz for 24P, 30P and 60I sources and 100Hz for 25P and 50I sources.
Good to see mainstream devices with this feature. Big hint to Youview, a feature worth having.