Improve MI2S touchscreen accuracy

[guari]

MI2S touchscreen has a noticeable high latency and a low resolution (touch resolution) compared to all other middle and high-end touch devices.
You can easily see it when using drawing apps or some others that need an accurate touch response.
After doing some little tests I noticed that my four years old Samsung phone with superamoled display has a latency three/four times lower than my xiaomi (if you quickly draws lines with your finger with eg. Autodesk sketch app with MI2S you can see that only a part of the lines are drawn on the canvas and they are drawn with a very high delay of about 0.3 seconds while the other touchscreens I tried draws every line traced and with no noticeable delays).The same happens with touch resolution, my old Samsung has an accuracy of about less than 1 millimeter while Mi2S has about 3 or 4 millimeters (you can't draw a point with MI2S without doing a short line with your finger) and also the sensibility of the touch is worst in xiaomi. These issues cannot be seen easily while moving on menu or using the keyboard but makes some apps unusable due to the bad touch response.
My test are made with recent MIUI, but those are things that usually can be solved with a better touch driver or with a better calibration in driver configuration files (assumed that the touch hardware used by xiaomi isn't a poor one...).
Those issues can also be more evident if you use a touchpen/stylus.

So I was wondering, do you know if some workarounds or fixes can be used?

 

[JOHNSON]

MI2S touchscreen has a noticeable high latency and a low resolution (touch resolution) compared to all other middle and high-end touch devices.
You can easily see it when using drawing apps or some others that need an accurate touch response.
After doing some little tests I noticed that my four years old Samsung phone with superamoled display has a latency three/four times lower than my xiaomi (if you quickly draws lines with your finger with eg. Autodesk sketch app with MI2S you can see that only a part of the lines are drawn on the canvas and they are drawn with a very high delay of about 0.3 seconds while the other touchscreens I tried draws every line traced and with no noticeable delays).The same happens with touch resolution, my old Samsung has an accuracy of about less than 1 millimeter while Mi2S has about 3 or 4 millimeters (you can't draw a point with MI2S without doing a short line with your finger) and also the sensibility of the touch is worst in xiaomi. These issues cannot be seen easily while moving on menu or using the keyboard but makes some apps unusable due to the bad touch response.
My test are made with recent MIUI, but those are things that usually can be solved with a better touch driver or with a better calibration in driver configuration files (assumed that the touch hardware used by xiaomi isn't a poor one...).
Those issues can also be more evident if you use a touchpen/stylus.

So I was wondering, do you know if some workarounds or fissa can be used?

Try LagFix Free app from Play Store https://play.google.com/store/apps/details?id=com.grilledmonkey.lagfix

 

[guari]

Try LagFix Free app from Play Store https://play.google.com/store/apps/details?id=com.grilledmonkey.lagfix

As far as I know, TRIM process is to deal with the loss of performance of the storage/mmc that you can have after storing/deleting a lot of files on the phone storage. It has nothing to do with touch accuracy/response, it is related to long access times from storage that can generate micro-lags.
In the case of MI2S there are no lags at all, simply the touch accuracy is bad compared to other devices
Currently, I have MIUI installed so I don't know if with CM 11 roms the touch driver has been updated and this issue is solved...

 

[MiKhan]

@guari: can you try the sensitivity in some of the old releases of stock ROMs? (AOSP QDT14, weekly MIUI v5 released before September 2013.)

That might give an insight whether it is related to Xiaomi's kernel changes as a response to the phantom touches or not.

 

[Voodooman]

This thing that you report is very alerting for me. You see, one of the main things I do with my smartphone is keeping notes. My old galaxy S3 was very good at that and it is quite important for me the note taking capabilities of my smartphone. I have not received my MI2S yet and haven't tried it yet.
Are you sure that it has nothing to do with the program you use? I mean that Samsung's native memo app (S memo) was much more accurate compared to all the other apps I had tried, only papyrus could be a match for S memo. How many programs have you tried?

 

[guari]

This thing that you report is very alerting for me. You see, one of the main things I do with my smartphone is keeping notes. My old galaxy S3 was very good at that and it is quite important for me the note taking capabilities of my smartphone. I have not received my MI2S yet and haven't tried it yet.
Are you sure that it has nothing to do with the program you use? I mean that Samsung's native memo app (S memo) was much more accurate compared to all the other apps I had tried, only papyrus could be a match for S memo. How many programs have you tried?

I tried the same version of the same apps on different devices, I used the best apps for drawing and taking notes: with these apps the touch response/accuracy on MI2S is always the same (bad) described above, so it is not related to app used but to the touch hardware/driver.

I made another little test, using Papyrus app, last version from playstore installed on:
- Xiaomi MI2S 32GB (4.3 inch display 1280x720px, android 4.1 stock MIUI 21.2.14)
- Samsung Wave S8500 (3.3 inch display 800x480px, android 4.4 CM11 developed and ported completly from scratch by others great devs, but previously I had the same touch feedback also with a CM10 rom);

Here are some screenshots after testing the app to write something with my finger on both the devices, note that the samsung is a 2010 device, with a significantly smaller screen that should make writings harder (writing with a finger on a phone is already an hard task..), lower resolution, with a rom developed by a couple of guys in their free time and that it wasn't an android device (it had Bada OS)... just to point out at least xiaomi bad driver optimization...

MI2S on the left, S8500 on the right:

MI2S on the left, S8500 on the right:

MI2S on the left, S8500 on the right:


RESULT: there is no competition at all, S8500 has way better touch accuracy and quickly response. It's very very hard to write something readable on MI2S because what is drawn on the screen doesn't match closely with the path touched (you can notice from the screenshots that the paths/letters drawn are jagged and incomplete).
I also tried the same thing on a 'cheap' samsung galaxy advance I9070, that, with a bigger screen and native android drivers, has a better response than S8500 too.

 

[oile]

Tried the app. Same ****** results. I agree with you but I don't know if it is a driver problem or a hardware problem

 

[Suspiria]

Is there a pen available like for the SNote serie ?
Could it help for accuracy or screen pression ?

 

[Voodooman]

Is there a pen available like for the SNote serie ?
Could it help for accuracy or screen pression ?

There are many passive pens, not active like the Spen. I have tried three different types, this one is the best. A Stylus really helps a lot and it's far more accurate than finger.
You have really disappointed me, I will try the phone and if I can't keep good notes, I'll sell it right away, notes is that important for me...

 

[guari]

There are many passive pens, not active like the Spen. I have tried three different types, this one is the best. A Stylus really helps a lot and it's far more accurate than finger.
You have really disappointed me, I will try the phone and if I can't keep good notes, I'll sell it right away, notes is that important for me...

the same disappointment I had too, after I tried some apps. I wanted to use it also to take notes and as a small graphics tablet. It should be a common usage for a touch device with a capacitive screen.. but that's how it is, at least for now.. touch accuracy is the biggest limit on this screen (and, maybe, the only one that can be solved), response time is under the average, sensibility is less than amoled but it's in the average, the number of tracked finger is great (at least 10, tested with Synaptics TouchExplorer app).
Anyway I haven't tested M1cha roms and I don't know if are compiled with different touch driver.. maybe someone else can give other feedbacks or solutions...

However, how can we see the touch hw vendor/model and driver version?

Inviato dal mio MI 2S utilizzando Tapatalk

 

[Voodooman]

Today I received my phone and it seems that you are right. I am using the stylus I mentioned above and I have to say that writing is not impossible, but it certainly is not easy, at least as it used to be with my Galaxy S3. The main problem I see is that the screen has a hard time to draw round and diagonal lines, so letters do not look as they should.
My results are not totally unusable for me, but they are not good at all. I sure hope that xiaomi can improve this via a software update.

 

[guari]

Today I received my phone and it seems that you are right. I am using the stylus I mentioned above and I have to say that writing is not impossible, but it certainly is not easy, at least as it used to be with my Galaxy S3. The main problem I see is that the screen has a hard time to draw round and diagonal lines, so letters do not look as they should.
My results are not totally unusable for me, but they are not good at all. I sure hope that xiaomi can improve this via a software update.

That's because touch resolution is very low, is like you draw something on eg. a 180x320 input matrix that is interpolated to a 720x1280 canvas matrix.
I don't know if it can be solved, but probably it can be improved on driver side. What I can I say you is that with my old samsung S8500 the touch accuracy and response time (lags) were bad with native Bada OS (not as bad as MI2S but similar), then they became perfect with all the android roms ported (Bada wasn't linux-based, touch screen drivers are completely different and makes the difference).

 

[Voodooman]

I have some good news and some bad news.
The good news is that I got better results. Right now photobucket is down, I'll upload my result as soon as possible.
The bad news is that I had to remove the official screen protector. It maybe too thick, I don't know. Of course, I do not want to have my screen unprotected, so I ordered 3 different kinds, to see if that can help.

Here you are!

 

[guari]

I made another little test, probably the Mi2S touch sensor is good but the touch driver has some clear issues.
Install this app:
https://play.google.com/store/apps/details?id=com.synaptics.touchexplorer
run it and then select 'Target' from the app menu. Now place your finger on the screen and move it very slowly in one direction (like a swipe gesture).
1) Slowly swipe, then try to stop without releasing the touch, then continue to move extremely slowly in the same direction: you should see that the crossed line on the screen will be painted with an high accuracy moving from pixel to pixel.
2) Now try to do the same but while you are swiping your finger invert your direction (eg. if you are slowly moving to left, stop without lifting your finger from the screen then very slowly move it to right): you should notice that when inverting direction the line will be painted with an initial 'lag', about 10-15 pixel away from the position where you started to invert your moving direction.

This should be an issue of the software (driver) algorithm and it's why drawing or writing result on the Mi2/Mi2S screen are very bad (when drawing or writing you always modify the swipe direction of your finger and every time you do this the driver lose the accuracy)

Inviato dal mio MI 2S utilizzando Tapatalk

 

[Voodooman]

Sorry for not updating earlier, I have made some fundamental changes in my Mi2S and here are the results.
As I said, the official screen protector was making things worst, at least in my case. I finally settled with an aftermarket matte one, it did not help accuracy, but I find it more attracitve!..
I am currently using Cyanogenmod 11 Rom. I feel that note taking has become easier and more precise. Maybe I've got used to Mi2S, maybe it's a placebo effect, but the bottom line is that note taking is not a big problem for me anymore. As far as i can recall, taking notes with Galaxy S3 was easier, but maybe Mi2's smaller screen is to blame. Anyway, here's a sample with a good enough stylus, the matte screen protector and Cyanogenmod 11 ROM, This note was a one-shot try, I only made two small corrections. Not bad for my taste and needs, but I'll try the app you proposed also and I'll report results.



Quick update.
You are correct, Touchexplorer is behaving exactly as you said. The above result is good enough for the use I need it for. Nevertheless, the fact is that there is room for improvement. Thanks for your in-depth investigation!