Develop Bugs

[Q] Why is the refresh rate on the Note 2 58hz?

Hello folks,
I have had my Note 2 for a couple of days now and almost immediately noticed something strange. There is a VERY subtle flickering of the white and light grey areas of the screen. A very high frequency flicker, almost like I can see the refresh rate of the screen. My initial suspicion was that the refresh rate was lower than 60hz. So, I downloaded the app called Android System Info, and sure enough, under display, it was being reported that the refresh rate of the screen is 58hz. I got another friend with a Note 2 to confirm the same thing. My GS3 reports 60hz, and so does my friends HTC One S. So my question is, why is the refresh rate on the Note 2 not 60hz? Is this an intrinsic hardware limitation? Or can this be changed with software? My eyes can definitely notice the 2 less frames per second, I was using a GS3 since June, and switching to the Note, I immediately noticed the refresh rate was lower. Why? This is very strange to me. There are many videos on YouTube with the Note 2 and GS3 on the screen at the same time, and sometimes there is banding interference on one phone and not the other, meaning obviously the phones are running different refresh rates. Now I know the Note 2 refresh rate is lower, why? And is there anyway to change it with software?
Thanks much!

first, i think u should get yr note2 to warranty,
second, u sure yr eyes can differentiate 58hz and 60hz......?

emprize said:
first, i think u should get yr note2 to warranty,
second, u sure yr eyes can differentiate 58hz and 60hz......?
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It is EXTREMELY subtle, almost a non issue, so I doubt warranty will even say anything is wrong. I can notice it on all the demo models i've seen, so I doubt it has anything to do with my phone.
I have confirmed on 3 different Note 2s, the reported refresh rate in the app 'Android System Info' is 58hz. While all other phones I have used report 60hz.
I just find this so strange that maybe someone has a great explanation as to why this is the case. And maybe someone can dig deeper than I can and figure out if this is in the OS or an intrinsically hardware thing. I wish I had the email of a Samsung engineer who worked on the design of this phone, would love their take on why this is the case. 58hz is just such a strange refresh rate.

Goontron said:
It is EXTREMELY subtle, almost a non issue, so I doubt warranty will even say anything is wrong. I can notice it on all the demo models i've seen, so I doubt it has anything to do with my phone.
I have confirmed on 3 different Note 2s, the reported refresh rate in the app 'Android System Info' is 58hz. While all other phones I have used report 60hz.
I just find this so strange that maybe someone has a great explanation as to why this is the case. And maybe someone can dig deeper than I can and figure out if this is in the OS or an intrinsically hardware thing. I wish I had the email of a Samsung engineer who worked on the design of this phone, would love their take on why this is the case. 58hz is just such a strange refresh rate.
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you are the man, mate, my eyes cant even differentiate 50 and 60 Hz, for all my note2 experience, i cant see any unusual on the screen.
But for the 58hz issue, i think its not quite a strange thing for me, it reminds me when i was using CRT monitor(or early lcd?), it always can set the refresh rate to 58hz or 60hz, but it might like u say a hardware or driver problem, hope u can contact with samsung engineer and tell us the answer

I suppose the app might be reading the values of somewhere not actually measuring it or something ! Correct me if am wrong .

this is interesting. i also notice a subtle flicker of the screen. it's annoying in some lighting. i don't notice it on other phones.. it's definitely seems like the refresh rate is a bit slower than it should be.

The refresh rate is correlated with the resolution and the main base clock which feeds the display controller, in this case 1280 * 720 * 58Hz = ~54Mhz plus some margins for which are too long to describe, which gives them a target frequency of about 54MHz for a 16 divider of the 880MHz base clock. That's the main reason of the 58 vs 60 Hz difference.
But the reason you're seeing flickering might be completely unrelated to that and caused by some odd much lower timings in the display settings. Maybe a developer with the device could test it out by changing them.

AndreiLux said:
The refresh rate is correlated with the resolution and the main base clock which feeds the display controller, in this case 1280 * 720 * 58Hz = ~54Mhz plus some margins for which are too long to describe, which gives them a target frequency of about 54MHz for a 16 divider of the 880MHz base clock. That's the main reason of the 58 vs 60 Hz difference.
But the reason you're seeing flickering might be completely unrelated to that and caused by some odd much lower timings in the display settings. Maybe a developer with the device could test it out by changing them.
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Thanks for that information, it's great technical info I've been looking for. So it's basically a ratio/multiplier of some clock speed in the hardware. But now my question is, why would the Note 2 be any different than a GS3? I would think they have relatively the same hardware, and resolution on both screens is the same, so why would the refresh rates differ? Just seems to me that 58hz is not an ideal refresh rate. I mean, the main reason there is a trend towards 120hz TVs these days is because both movies (24 fps) and TV (30 fps) are evenly divisible into 120. Whereas with a 60hz TV, there is a remainder on 24, so movies do not interpolate as smoothly. With 58hz, no recorded content I can think of divides evenly into it, always making interpolation less smooth. Again, in my mind, 58hz is just silly, why not just give me the extra 2hz!! Doesn't make sense to me.
Final question. Would there be any way with software to change the refresh rate? Or is this set in stone at the hardware level?

I have an issue with this as well - I'm getting either fairly heavy frame skipping in any 8 or 16 bit emulator with frame skipping set to auto, or sound skipping with frame skipping turned off. I suspect this is because of the odd refresh rate with the app expecting 60hz and only running at 58 in reality, causing either the video or audio to run out of sync and needing to skip the two frames here and there to catch up. If the emulators could slow down the audio speed to match the slower video speed, it wouldn't be an issue.... but this shouldn't be the problem of the emu authors.
This happens with no other applications installed on a brand new phone. I've also installed clean rom and perseus kernel, no change. Power settings are all off, nothing is hitting my CPU to cause the frameskipping and it's very consistent, which leans towards the refresh rate causing the issues. Anyone know anything more about this? What a pain...

I am a traffic cop and I can definitely tell the difference between a car going 58mph and one going 60mph.
Sent from my GT-N7100

@rbiter said:
I am a traffic cop and I can definitely tell the difference between a car going 58mph and one going 60mph.
Sent from my GT-N7100
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I'm a noob and I don't know what "stuttering" is
But seriously, it's not like a mobile device should be able to emulate another system anyway, am i rite? Just use it for phone calls and internet browsing...

i think the reason why the refresh rate between gs3 and note2 is different due to both are using different lcd even though some of the hardware is the same.
even though the diff is small but it still incur some major hiccup where the frame skip especially with project butter where they keep the ui at 60fps.
maybe we can email to samsung engineer and they can take a look at it.

[Q] Does the Galaxy Note 8.0 have PWM?

It would be great if somebody can test it, thanks in advance.
How to test:
put a camera in front of the screen and play around with the shutter speed and the brightiness of the screen. When lines appears on the screen, its not good => pwm, without lines => good :good:
edit: i had links for pwm explanation, but not enough posts, sorry..

The question is about pulse width modulation, which I'm reading occurs when both of the following are true:
- you are using an LED light source with variable brightness
- you are using a camera with a rolling shutter
http://provideocoalition.com/aadams/story/pulse_width_modulation_is_not_your_friend/
The camera on the note 8 does not have an LED flash, so I think the poster either now knows that it won't be an issue, or is curious as to whether display brightness on the screen is controlled by pulse width modulation or a different technique.
In the latter case, I don't know, and since this is stuff that can't be seen by the eye nor in the viewfinder, but mostly in photo editing suites per the article I link to, I'm not sure why it's an issue here.

Hi roustabout
I think we dont speak about the same topic.
What I mean is the flickering of the display. A good example is found on youtube: Nexus 7: no PWM on LCD
A lot of LCD use this technology to dim, but its not proper dimming, just switch on / switch off the the lcd very quickly.
Some people have problem with this flickering but dont know that theres a problem, so for example dry eyes, getting tired very fast when working on the computer..
I think more the 95% of the usual monitors use this technique.
I hope this helps.

no, we're talking about the same thing:
'curious as to whether display brightness on the screen is controlled by pulse width modulation or a different technique.'
The article I found thinks it's not visible; what you've read or experienced suggests it's problematic.
What I can say is the first-gen ipad was very hard on my eyes; the note 8 is not like that, but not as good as e-ink. Much more fun than e-ink, though!

[Q] Does the note 10.1 (2014) use PWM at all level of brightness?

Hi, my english won't be very good because it's not my native langage.
I'm very sensitive to the flicker caused by PWM (Pulse Width modulation) wich is a technique used in the backlighting of a lot of LCD display to dim the brightness of the screen. I'm a "migraineur with aura" wich is a neurological disease, so like epileptic people my eyes and my brain are very sensitive to all sort of visual stress even the most subliminal one like PWM used at a high frequency. And I wanted to know if the note 10.1 (2014) use PWM to dim the screen at all level of brightness? I m' sure that it use it a least until 50 %, and that it is not PWMed at 100% brightness. Cause at 50% i'm sick litteraly within second, and at 100% i'm ok. But I have not tested all the level between 50 to 100 cause if it's flicker I can have quite a serious seazure, which would leave me ill for days, so it's quite hasardeous for my health. So what i'm doing is that i leave the system brightness to 100% wich of course is too bright, but I dim it with a soft (screen adjuster) that can dim the display without touching the backlight. But it's not a perfect solution cause the display is still using a lot of energy that way and there's a lot amount of blue wavelenght coming from it and i'm sensitive to blue wavelenght too. Basically as you can see, LED backligh is not a very good technology for epileptic people, eye-sensitive or migraineur. (I personally think it's not a healthy tec for anybody)
So, I just wanted to know if someone know if there's an "official" level where the note doesn't use PWM anymore to control the brightness of the screen, I mean below 100? Thanks in advance, and i'm sorry if my post can sound a bit confuse, it's not easy to try to ask and explain something in a langage that's note your native langage. Thanks in advance.

Do the Pixel/Pixel phone displays use PWM?

Maybe an odd question for XDA, but a question I need answered before I pull the trigger on this phone. Earlier this year while buying a new television set, I learned that I am amongst a small minority of people who are sensitive to LED-lit electronic displays that use pulse width modulation to control brightness. Apparently, I can look at a PWM CCFL-backlit (i.e. my 5-year-old computer monitor or my Nexus 5) screen or a DCM LED-backlit screen (my television set) for hours with no issue whatsoever but I can only focus on a PWM LED-lit screen briefly before I start experiencing symptoms of eyestrain and motion sickness. It's like looking at a CRT that flickers because the refresh rate is set too low. Now I know an AMOLED lacks a backlight layer, but it still has to adjust for brightness, so if it uses PWM to do so, then I have to presume it will cause the subtle flicker leading to the same problems that I've experienced with LED-LCD displays. Is there anyone here who could possibly shed some light (no pun intended) on this issue?

Yes, it uses PWM. My suggestion is to buy the phone, and if it bothers you, utilize the return window where you will receive a full refund.

Android P what have they done with the brightness?

Just installed P and now previous brightness level of 63 it's so dim? I have to have it almost on 90% brightness now, why have they messed with this, it was fine as it was

Ady1976 said:
Just installed P and now previous brightness level of 63 it's so dim? I have to have it almost on 90% brightness now, why have they messed with this, it was fine as it was
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Same for me. WTF Google?

The actual brightness is the same, they just changed how the slider works. The first half moved it fast, last half moved it slower. Now the slider is more uniform.

https://www.androidpolice.com/2018/...c-brightness-slider-introduced-android-p-dp3/
Sent from my Pixel 2 XL using Tapatalk

It's definitely not smooth across the entire range, all my brightness is almost all the last 10% and actually a pain to set properly, it's worse for me.

That's more accurate because in bright indoor lighting or outside it's going to be towards the end of the scale. Dim indoor lighting I'm currently at 43%. And in pitch black it goes to 0%. I pretty much never touch my slider anymore after a couple adjustments. Don't get caught up on the percentages. I would be willing to bet that with Oreo at 40% and Pie at 90% the lumens output of the screen was the same.
Ady1976 said:
It's definitely not smooth across the entire range, all my brightness is almost all the last 10% and actually a pain to set properly, it's worse for me.
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Sent from my Pixel 2 XL using Tapatalk

EeZeEpEe said:
That's more accurate because in bright indoor lighting or outside it's going to be towards the end of the scale. Dim indoor lighting I'm currently at 43%. And in pitch black it goes to 0%. I pretty much never touch my slider anymore after a couple adjustments. Don't get caught up on the percentages. I would be willing to bet that with Oreo at 40% and Pie at 90% the lumens output of the screen was the same.
Sent from my Pixel 2 XL using Tapatalk
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Yeah I don't touch mine once it is setup generally but it's definitely not even throughout the scale, only gets really bright from like 85% onwards, just seems odd the real brightness is so high up, makes for fine tuning a bit difficult.

The screen has been rated a minimum of 1.78 nits and a maximum of 496 so if it truly is linear now, 50% is something like only 247 which isn't that bright at all.
Ady1976 said:
Yeah I don't touch mine once it is setup generally but it's definitely not even throughout the scale, only gets really bright from like 85% onwards, just seems odd the real brightness is so high up, makes for fine tuning a bit difficult.
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Sent from my Pixel 2 XL using Tapatalk

Hi
So much for AI on adaptive brightness, it's rubbish, and why do Google try to fix things that aren't broken, who needs AI for adjusting a backlight? Seems nothing more than just being able to market the phone as having AI! Never had an issue on Oreo, had it set at 25% with adaptive brightness and it was always the correct brightness wherever I was, which shouldn't be difficult given it's got a sensor to read the light levels.
Now since Pie, last night I turned my phone on in the dark and was blinded by a bright display (Oreo it would have been at it's lowest level in the dark), so turned the brightness down, turned it again later and the same thing, way too bright, and again this morning in a fairly dark room the same thing, far too bright, so I turn it down again. How long will it take to learn? The old method it was tamed immediately, now I'm constantly fiddling with the brightness, how is that progress!
Is there an option to go back to the old method?
Wish I hadn't bothered upgrading, just another year with an Android update with changes for changes sake.
Regards
Phil

PhilipL said:
Seems nothing more than just being able to market the phone as having AI!
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Totally agree on this. Adaptive battery and adaptive battery are almost non-sense. Only something cool to brand the item.
And Pixel Visual Core is just something super-expensive to make Whatsapp, Facebook and Twitter cameras use HDR+. I'd rather pay something less and not having this feature that is probably expensive (or modifies the perception of the Pixel 2 as super-new and mega futuristic). Also, I've got the feeling they won't use it for Pixel 3 or 4.
Moto X1 was the last to use more CPUs to optimize the phone, before Qualcomm introduced more chips.

Hi
For any one having this issue please report this from your device at Settings > System > About Phone, the more people that flag it the more likely it will get fixed.
For me, I hate these updates that break simple basic functionality and overall add nothing extra to what we had with Oreo. Google really need to test these things properly and stop trying to fix things that simply are not broken!
Regards
Phil

PhilipL said:
Hi
For any one having this issue please report this from your device at Settings > System > About Phone, the more people that flag it the more likely it will get fixed.
For me, I hate these updates that break simple basic functionality and overall add nothing extra to what we had with Oreo. Google really need to test these things properly and stop trying to fix things that simply are not broken!
Regards
Phil
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Already reported, i shouldn't have to have my phone on 90% to be the same as what it was on 63%