[Q] Why is the refresh rate on the Note 2 58hz? - Galaxy Note II Q&A, Help & Troubleshooting

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......?
Click to expand...
Click to collapse
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.
Click to expand...
Click to collapse
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.
Click to expand...
Click to collapse
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
Click to expand...
Click to collapse
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.

Related

'Auto Brightness Backlight Flicker' looks to be power management related...

This thread deals specifically with the 'Auto brightness backlight flicker'. Which only occurs when the phone is set to 'Auto brightness'.
This does not deal with the various other screen glitches, or the constant flicker at various brightness levels when looking at grey screens.
Please do not get the two issues confused.
_____________________________________________________________________________________________
I have observed a few patterns, on two seperate handsets with the same symptoms....
*Firstly, the flicker occurs while the CPU is under load, and particularly at lower battery levels.
*Secondly, The flicker occurs momentarily when you plug in a charger.
*Thirdly, The flicker doesn't occur while the device is charging.
*Fourthly (is that even a word), The flicker is often seen immediately after a screen settles, such as when the screen stops moving after scrolling.
All of these things are evidence of a power management issue. As if the backlight voltage is not being regulated correctly.
I did some more testing over the last few hours and have found something interesting. If you go to 'Settings' - 'Developer Options' - and enable 'Show Screen Updates', your phone will blink the screen different colours whenever the screen is updated. I found that when the screen settles, the screen is updated one final time, just a moment after it has settled. This is exactly when the flicker occurs. As i see it, this is further evidence that the flicker is power management related.
It seems to me that when the CPU goes from load to idle and changes its power draw, the backlight voltage regulation does not filter these fluctuations and the backlight flickers.
The question is, can this be altered either by the power management built in to the kernel, or by other power management software? Or is it a physical design flaw in the power regulation circuit?
The fact that the fluctuation only seems to occur when the brightness is set to auto leads me to believe that it indeed can be fixed with software.
If it was a physical supply voltage fluctuation when the CPU goes from load to idle, it would surely flicker all the time, not only on Auto Brightness.
I assume that the CPU voltage is altered by the kernel as the load level changes.
My question is, if the governor is changed to one which doesn't allow the CPU to scale or voltage step, does the issue go away?
Is there anyone out there who has rooted their device and can test my theory? I don't want to root my device as I may need to send it back DOA (it's only a day old).
If you can change the governor to a profile which doesn't allow stepping or voltage adjustment (100% Voltage and Frequency all the time), and the problem goes away, we have an answer and HTC can work on developing a new Kernel to fix the issue.
Thanks!!
Sentinel196 said:
Please do not get the two issues confused.
Click to expand...
Click to collapse
It is highly likely that all the graphics issues are related. This includes various types of flickering, notification bar corruption, and strange bands in the camera app. Similar issues occurred with the Teg3 Asus Prime when it launched and all were corrected with updates. There are also some performance variations that can be seen in benchmarks when the issues are at their peak that go away when the phone's rebooted.
Nvidia, not HTC (or the devs) controls the Teg3 low-level code, drivers, and kernel. All this has been discussed in the other two threads. As has a communication from HTC UK received yesterday that they've identified the issue and will be issuing an update (not 1.29) to address it.
64 pages of flickering and graphics issues discussion here:
http://forum.xda-developers.com/showthread.php?t=1617009
Thanks for the info. I'm well aware of the other thread and have been following it closely.
Not looking to start a debate about the cause and if the problems are related. Just looking for someone to help me test my theory.
Sentinel196 said:
This thread deals specifically with the 'Auto brightness backlight flicker'. Which only occurs when the phone is set to 'Auto brightness'.
This does not deal with the various other screen glitches, or the constant flicker at various brightness levels when looking at grey screens.
Please do not get the two issues confused.
_____________________________________________________________________________________________
I have observed a few patterns, on two seperate handsets with the same symptoms....
*Firstly, the flicker occurs while the CPU is under load, and particularly at lower battery levels.
*Secondly, The flicker occurs momentarily when you plug in a charger.
*Thirdly, The flicker doesn't occur while the device is charging.
*Fourthly (is that even a word), The flicker is often seen immediately after a screen settles, such as when the screen stops moving after scrolling.
All of these things are evidence of a power management issue. As if the backlight voltage is not being regulated correctly.
I did some more testing over the last few hours and have found something interesting. If you go to 'Settings' - 'Developer Options' - and enable 'Show Screen Updates', your phone will blink the screen different colours whenever the screen is updated. I found that when the screen settles, the screen is updated one final time, just a moment after it has settled. This is exactly when the flicker occurs. As i see it, this is further evidence that the flicker is power management related.
It seems to me that when the CPU goes from load to idle and changes its power draw, the backlight voltage regulation does not filter these fluctuations and the backlight flickers.
The question is, can this be altered either by the power management built in to the kernel, or by other power management software? Or is it a physical design flaw in the power regulation circuit?
The fact that the fluctuation only seems to occur when the brightness is set to auto leads me to believe that it indeed can be fixed with software.
If it was a physical supply voltage fluctuation when the CPU goes from load to idle, it would surely flicker all the time, not only on Auto Brightness.
I assume that the CPU voltage is altered by the kernel as the load level changes.
My question is, if the governor is changed to one which doesn't allow the CPU to scale or voltage step, does the issue go away?
Is there anyone out there who has rooted their device and can test my theory? I don't want to root my device as I may need to send it back DOA (it's only a day old).
If you can change the governor to a profile which doesn't allow stepping or voltage adjustment (100% Voltage and Frequency all the time), and the problem goes away, we have an answer and HTC can work on developing a new Kernel to fix the issue.
Thanks!!
Click to expand...
Click to collapse
i like the theory, but on the 4 out of 6 handsets i've had, the flicker started off only on auto brightness, then got worse over a day or two, and then would develop into a constant flicker, regardless of backlight settings.
Well i really hope thats not the case here as I only have 10 hours left of DOA return window. :S
Sentinel196 said:
This thread deals specifically with the 'Auto brightness backlight flicker'. Which only occurs when the phone is set to 'Auto brightness'.
This does not deal with the various other screen glitches, or the constant flicker at various brightness levels when looking at grey screens.
Please do not get the two issues confused.
_____________________________________________________________________________________________
I have observed a few patterns, on two seperate handsets with the same symptoms....
*Firstly, the flicker occurs while the CPU is under load, and particularly at lower battery levels.
*Secondly, The flicker occurs momentarily when you plug in a charger.
*Thirdly, The flicker doesn't occur while the device is charging.
*Fourthly (is that even a word), The flicker is often seen immediately after a screen settles, such as when the screen stops moving after scrolling.
All of these things are evidence of a power management issue. As if the backlight voltage is not being regulated correctly.
I did some more testing over the last few hours and have found something interesting. If you go to 'Settings' - 'Developer Options' - and enable 'Show Screen Updates', your phone will blink the screen different colours whenever the screen is updated. I found that when the screen settles, the screen is updated one final time, just a moment after it has settled. This is exactly when the flicker occurs. As i see it, this is further evidence that the flicker is power management related.
It seems to me that when the CPU goes from load to idle and changes its power draw, the backlight voltage regulation does not filter these fluctuations and the backlight flickers.
The question is, can this be altered either by the power management built in to the kernel, or by other power management software? Or is it a physical design flaw in the power regulation circuit?
The fact that the fluctuation only seems to occur when the brightness is set to auto leads me to believe that it indeed can be fixed with software.
If it was a physical supply voltage fluctuation when the CPU goes from load to idle, it would surely flicker all the time, not only on Auto Brightness.
I assume that the CPU voltage is altered by the kernel as the load level changes.
My question is, if the governor is changed to one which doesn't allow the CPU to scale or voltage step, does the issue go away?
Is there anyone out there who has rooted their device and can test my theory? I don't want to root my device as I may need to send it back DOA (it's only a day old).
If you can change the governor to a profile which doesn't allow stepping or voltage adjustment (100% Voltage and Frequency all the time), and the problem goes away, we have an answer and HTC can work on developing a new Kernel to fix the issue.
Thanks!!
Click to expand...
Click to collapse
As for your first issue regarding flickering at lower power levels, have you tried accessing the power-saving settings and turning off the setting which changes brightness at lower battery levels? The method of accessing power-saving settings is outlined here: http://forum.xda-developers.com/showthread.php?t=1627517
oh well again i guess
NVIDIA PRISM Display Technology - PRISM (or Pixel Rendering Intensity and Saturation Management) reduces a mobile device’s backlight power while simultaneously enhancing the pixel color to deliver the same visual quality with substantially extended battery life.
Click to expand...
Click to collapse
http://www.nvidia.com/object/tegra-3-processor.html
Thanks. I'll test that out to see if it makes a difference too.
Still hopeful someone with root can test changing the scaling setting for the CPU.
hamdir said:
oh well again i guess
Click to expand...
Click to collapse
It's a great guess. The sensitivity of this being wonky was one of the things causing problems on the Prime. It also affected individual devices differently, was worse in certain apps, and was most prominent when the display was showing a predominantly dark background.
So how did they fix it?
Sentinel196 said:
So how did they fix it?
Click to expand...
Click to collapse
Drivers and low-level code. And it took four updates to get everything stabilized (battery usage, CPU performance/stepping, graphics). This has little to do with HTC (the XL having no similar issues) and everything to do with Nvidia.
designgears said:
Pretty sure this has to do with the crappy gfx drivers. The same thing that cause the camera to have issues and the notification bar. While I had the international one x, the phone benched really well while those problems weren't happening, but as soon as I was able to reproduce them and ran the tests again, score was reduced by a lot.
I could reboot the phone and the problems would go away, only to come back after some use.
Click to expand...
Click to collapse
http://forum.xda-developers.com/showthread.php?t=1619432
OK. So it looks like I'm on the right track and it's hopeful that this can be fixed in future updates
Thanks for the info.
Sentinel196 said:
OK. So it looks like I'm on the right track and it's hopeful that this can be fixed in future updates
Thanks for the info.
Click to expand...
Click to collapse
There were a bunch of really smart people and quite a few established devs on the Prime forum when it launched. When these problems started to occur, everyone was equally flummoxed. The one question that never was answered is why devices with identical h/w and s/w would perform differently and react to updates differently. Clearly they shouldn't. No one believed the issues could be corrected with s/w alone. Somehow they were. Neither Asus nor Nvidia ever answered the question as to the differences in individual device behavior. I don't blame anyone here for being skeptical. Something really funky is going on with Teg3 that no one will probably every truly understand. Truthfully, if the HSPA version of the One X was S4 too I’d have preferred it.
I guess it just comes down to variation in the tolerances of components.
I used to work in mil-spec electronics design and manufacturing and even with the tightest possible manufacturing tolerances, there was always variation.
BarryH_GEG said:
There were a bunch of really smart people and quite a few established devs on the Prime forum when it launched. When these problems started to occur, everyone was equally flummoxed. The one question that never was answered is why devices with identical h/w and s/w would perform differently and react to updates differently. Clearly they shouldn't. No one believed the issues could be corrected with s/w alone. Somehow they were. Neither Asus nor Nvidia ever answered the question as to the differences in individual device behavior. I don't blame anyone here for being skeptical. Something really funky is going on with Teg3 that no one will probably every truly understand. Truthfully, if the HSPA version of the One X was S4 too I’d have preferred it.
Click to expand...
Click to collapse
there is a lot to love about the Tegra mate, h264 video playback is amazing on it, also android is on steroids thanks to T3
but yes im with you on the issues, semi accurate reported crazy silicon issues, i don't find it hard to image that the Prism feature is just a cover up too
it was added later on the nvidia specs page
So, to sum this up guys - are you closer to say that flickering problem is actually only a matter of s/w?
I'm wondering how long it'll take HTC to admit that there are real issues and then how long we'll have to wait for the possible solution - replace, repair or just update the firmware :O
Anyways, this made me a bit more optimistic, since with unlocked bootloader it'd be hard to fight for the replacement
Sentinel196 said:
I guess it just comes down to variation in the tolerances of components.
I used to work in mil-spec electronics design and manufacturing and even with the tightest possible manufacturing tolerances, there was always variation.
Click to expand...
Click to collapse
Here's my theory. Nvidia's having yield issues with Teg3 and what's shippable is functional but varies in spec to a degree. The s/w is anticipating a range of responses from the h/w and what it's receiving is outside that range causing it to bork. Nvidia's "fix" is a combination of taming the h/w via low-level code and expanding what the s/w and drivers are capable of interpreting. And because of variations between chips, it's hard to test in a lab which is why it took four updates to resolve the Prime's issues. Again, just my theory.
I also believe both Asus and HTC were victims. There's no way both companies could be so ****ty at testing to have not caught this pre-production. My second theory is that Nvidia provided hand-picked chips early on that were right on spec and consistent so all the internal testing passed and units sent to professional reviewers all behaved optimally. It wasn't until production that inconsistencies between chips started to rear their ugly heads. Add to this that Nvidia's code, their drivers, and the kernel (still GB vs. ICS on the XL) are proprietary so both Asus and HTC are 100% dependent on them to resolve these issues.
Pretty ugly if I'm right.
BarryH_GEG said:
Here's my theory. Nvidia's having yield issues with Teg3 and what's shippable is functional but varies in spec to a degree. The s/w is anticipating a range of responses from the h/w and what it's receiving is outside that range causing it to bork. Nvidia's "fix" is a combination of taming the h/w via low-level code and expanding what the s/w and drivers are capable of interpreting. And because of variations between chips, it's hard to test in a lab which is why it took four updates to resolve the Prime's issues. Again, just my theory.
I also believe both Asus and HTC were victims. There's no way both companies could be so ****ty at testing to have not caught this pre-production. My second theory is that Nvidia provided hand-picked chips early on that were right on spec and consistent so all the internal testing passed and units sent to professional reviewers all behaved optimally. It wasn't until production that inconsistencies between chips started to rear their ugly heads. Add to this that Nvidia's code, their drivers, and the kernel (still GB vs. ICS on the XL) are proprietary so both Asus and HTC are 100% dependent on them to resolve these issues.
Pretty ugly if I'm right.
Click to expand...
Click to collapse
not hard to believe
one of the advertised features of Gerfoce 6 series was the pure video decoder, the entire 1st gen batch did not even work, it was broken in the silicon and Nvidia did not admit it until much later when the series was obsolete
hamdir said:
not hard to believe
one of the advertised features of Gerfoce 6 series was the pure video decoder, the entire 1st gen batch did not even work, it was broken in the silicon and Nvidia did not admit it until much later when the series was obsolete
Click to expand...
Click to collapse
Then you'll find this fascinating. Nvidia's PR exceeds their product’s capabilities by about 2:1.
http://semiaccurate.com/2012/05/01/why-cant-nvidia-supply-keplergk104gtx680/
BarryH_GEG said:
Then you'll find this fascinating. Nvidia's PR exceeds their product’s capabilities by about 2:1.
http://semiaccurate.com/2012/05/01/why-cant-nvidia-supply-keplergk104gtx680/
Click to expand...
Click to collapse
still you cant live without them bro, in our CG industry they are pioneers now thanks to their cuda cores and language
im sure they let marketing tint their transparency but semi accurate goes too far

Note 2 flickering display

What about this?
I make this video in the shop.
http://youtu.be/UoLb-9Sli_U
Why display flicker like a 60 Hz old monitor?
Samsung EPIC FAIL.
Exand said:
What about this?
I make this video in the shop.
http://youtu.be/UoLb-9Sli_U
Why display flicker like a 60 Hz old monitor?
Samsung EPIC FAIL.
Click to expand...
Click to collapse
Lmfao sorry what flicker. This ain't cm10.!
Exand said:
What about this?
I make this video in the shop.
http://youtu.be/UoLb-9Sli_U
Why display flicker like a 60 Hz old monitor?
Samsung EPIC FAIL.
Click to expand...
Click to collapse
Omg. Before posting such ridiculous nonsense why dont you go and look at a note 2 and avoid ending up looking like fool?
OP EPIC FAIL!
ADMIN please close this.
Sent from the Mighty Galaxy Note 2!
Neeeerrdddddd
Kcid
Sent from my SAMSUNG-SGH-I317 using xda premium
http://electronics.howstuffworks.com/question336.htm
The flicker is caused by two things:
A difference in the scanning frequency between the TV and the camera
A difference in the way the phosphor dots are perceived between the human eye and the camera's image sensor
Click to expand...
Click to collapse
It says TV and camera, but it's the same thing for your case.
These screens do flicker... like it or not.
Flicker while recording a screen, possible reasons:
The flicker is caused by two things:
A difference in the scanning frequency between the TV and the camera
A difference in the way the phosphor dots are perceived between the human eye and the camera's image sensor
Click to expand...
Click to collapse
I agree with that.
Still, these displays DO flicker.
To be specific: Galaxy S3 and Note 2.
There is a considerable amount of flickering on these displays, comparable with old CRT monitors switched to 60 Hz.
They glimmer like neon tubes. When you swing them fast, they don't leave continuous traces, but discrete, sliced traces.
Try it yourself. Denying it won't change it.
If you don't see it with your own eyes, then your eyes might be just a bit "lazier", or you might want to check them.
Whatever you do or don't do, try not to humiliate people who do see this flickering.
And yes, to the author of this thread: if you can, shoot Note 1 and Note 2 side by side, so you can eliminate these differences in frequencies from the quote above.
Wait, what frequencies? My Note 1 does not have a frequency... the pixels emit light continuously (only their value is changed every 60th of a second - if it's changed at all, not on still images - but they do not turn of and back on 60 times per second... unlike Note 2's).
I needed to run my old crts at 75 at least to not go crazy with flicker so you cant call my eyes lazy
Sent from the Mighty Note 2!
same problem
I too face the same flickering problem...do I get it replaced ?

[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!

HTC 10 screen flickering (PWM)?

Hi all!
Does anybody know if HTC 10 uses PWM (Pulse-width modulation) for brightness control?
PWM is a cheap and easy technology to manage screen brightness. To adjust brightness PWM-controller rapidly (usually with speed of 230-240 Hz) turns backlight on and off, which in turn could cause headaches and eye fatigue after using the device.
More about PWM: https://en.wikipedia.org/wiki/Pulse-width_modulation
Absence of PWM is one of the key parameters for me. Unfortunately only a few reviewers test flickering and this information is very hard to find. So far, I have not found a single review with PWM test.
Thank you!
21.05.2016 update: Notebookcheck confirmed that HTC 10 is flicker free!
Surely the only way to dim LEDs is with PWM?
Nope, PWM is just the cheapest an the easiest way. Plus controller won't overheat.
But there are other ways to dim LEDs. One of the oldest ways - variable resistor.
Considering humans see appx 60-90 hz I'd say this is a non-concern.
Unless you're a mutant who can see 100hz+ in which case you must go crazy anywhere you go from the constant exposure to higher frequencies.
Sent from my HTC One using Tapatalk
Considering that I had 5 laser eye surgeries this concerns me a lot.
Using a screen with PWM for more that 15 minutes causes eye strain for me. And this is the main reason why I haven't already bought Galaxy S7.
You are lucky that PWM doesn't affect your eye, and probably should google further more: https://www.google.ru/?#safe=off&q=pwm+eye+strain
datafoo said:
Considering humans see appx 60-90 hz I'd say this is a non-concern.
Click to expand...
Click to collapse
Where did you get that info? Especially flickering can be seen at even higher frequencies. I personally see flickering on the XPS 15 and it uses PWM at around 362 Hz.
http://www.notebookcheck.net/Dell-XPS-15-2016-9550-InfinityEdge-Notebook-Review.156354.0.html
It's not disturbing but it is noticeable.
http://www.100fps.com/how_many_frames_can_humans_see.htm
Also the difference between 60 Hz and 144 Hz in a monitor is obvious just by dragging windows around.
If you can't see it, fine. But don't go around telling untrue stuff please.
Dr. lele said:
Where did you get that info? Especially flickering can be seen at even higher frequencies. I personally see flickering on the XPS 15 and it uses PWM at around 362 Hz.
http://www.notebookcheck.net/Dell-XPS-15-2016-9550-InfinityEdge-Notebook-Review.156354.0.html
It's not disturbing but it is noticeable.
http://www.100fps.com/how_many_frames_can_humans_see.htm
Also the difference between 60 Hz and 144 Hz in a monitor is obvious just by dragging windows around.
If you can't see it, fine. But don't go around telling untrue stuff please.
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Click to collapse
Untrue stuff LOLOLOLOLOL - I believe you're suffering a nocebo effect.
Pardon my incredulity but as I mentioned if you see anything over 100hz you're a mutant (I said 60-90hz) and that appears to be corroborated by your 100fps link. I'm not completely disagreeing with you, I'm however pointing out that you're such a small subset of the population it's rare and hard to validate.
Although FPS and HZ are different we'll bypass the semantics for the fact we're discussing cycles per second in a general fashion.
It must drive you crazy being ANYWHERE with lighting and electricity. At least here in the US electricity runs at appx 60hz so lights (most computer monitors etc) must bother you quite a bit.
Either way, good luck to you. I hope you find what you're looking for.
There is of course a difference between the way LCDs refresh their content and the way CRTs did. Strobing of light can definitely be seen at much higher rates than you said.
Also I never said that it's infuriating or drives me crazy I just said it's noticeable. I have no idea where you get this from.
Tests with Air force pilots have shown, that they could identify the plane on a flashed picture that was flashed only for 1/220th of a second.
That is identifying. So it's pretty safe to say, that recognizing, that SOME light was there is possible with 1/300th of a second.
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Click to collapse
That was the part I wanted to show you.
Now the blur on LCDs is a different story, since the lights are on constantly and only the pixels change color at the given rate. But still you cann see the motion blur / dragging of the cursor even on a 144 Hz screen. Albeit much less noticeable than on a 60 Hz one.
If given a 60 Hz display side by side with a 144 Hz panel most people will be able to tell you which one feels more natural.
BTT: I don' think it will be a real poblem even if HTC does use a PWM module. Even though it might be somehow noticeable it won't disturb most people. Also: how often do you use your phone at the lowet brightness.
Yay! HTC 10 is PWM (flicker) free! Confirmed by Notebookcheck: http://www.notebookcheck.com/Test-HTC-10-Smartphone.164311.0.html (in German).
Oscillogram: http://www.notebookcheck.com/fileadmin/Notebooks/HTC/10/response_pwm.jpg
Just want to add that being able to notice it and it affecting you are two different things. Normally you can't notice neon lights flicker but they do and it will strain your eyes and make you tired. That's why bars have started to charge them out to leds.
Sent from my HTC 10
Glad I'm not effected by this crap. I'd hate having to pass on phones I really like just because they use PWM.
Sent from my SM-G935T using Tapatalk

VERY weird scan lines on low light

Hey guys. So I was at a restaurant earlier this evening and I was about to take some pics with my 5t when I noticed something really weird. Black vertical lines zooming from side to side on the image. The lighting was relatively dim and I noticed it stops when I focused on a white plate.
I tried with different camera apps and it kept happening. I took some videos to show you guys. I'm really hoping this is not a hardware issue because I'd hate to send the phone back.
Have any of you had these issues? Any thoughts?
Here are the videos:
And this one shows it happens with photos as well:
HALP
that ain't no issue. that's common on any camera.
It is the refresh rate of the screen and the lights not matching up. TV in the UK is broadcast at 24 fps, so lighting in the UK is tailored to match at 24hz.
you'll see those lines on poor light/LEDs on preview mode only. some camera apps have the option to change the hz from US to UK.
Abaddon said:
that ain't no issue. that's common on any camera.
It is the refresh rate of the screen and the lights not matching up. TV in the UK is broadcast at 24 fps, so lighting in the UK is tailored to match at 24hz.
you'll see those lines on poor light/LEDs on preview mode only. some camera apps have the option to change the hz from US to UK.
Click to expand...
Click to collapse
I had no idea lighting could mess with the refresh rate of a camera. It's weird because the problem is not only on videos. When I snap a picture the lines are there also. Is that because of the refresh rate too? On a still image?
I too have the same problem
Abaddon said:
TV in the UK is broadcast at 24 fps, so lighting in the UK is tailored to match at 24hz.
Click to expand...
Click to collapse
Excuse me but no. Standard TV is 50Hz, and I bet at least some HD channels transmit in 50Hz. Regardless of this the AC switching rate is 50Hz. Unless you're talking of another UK (I was referring to the one with the Queen).
Is this an isolated case or is it another oneplus problem like oneplus 5?
OrtizFerrari said:
Is this an isolated case or is it another oneplus problem like oneplus 5?
Click to expand...
Click to collapse
It's not a problem at all... It's how cameras pick up certain lights since they refresh at different rates. Try recording a tv or computer screen. You'll likely see it flickering the same way.
mazdamiata210 said:
It's not a problem at all... It's how cameras pick up certain lights since they refresh at different rates. Try recording a tv or computer screen. You'll likely see it flickering the same way.
Click to expand...
Click to collapse
Yes I know that differents frecuences could make interferences, but I bought the phone after a bad experience with the Oneplus 5 jelly and I'm worried haha Great to read that, thanks!
Just wanted to confirm that there's no issue. Tested with a Oneplus One and a Samsung Galaxy S5 camera. Both had the same effect under that lighting. I guess I learned something new.
Ok, could one moderator close this thread? Because someone can think that this is an issue of the phone...Anyway, I like to see that you've learned something new @Lord Zafakon

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