How to change DPI on Jelly Bean?

Question

Android

Colleagues, tell me!
I purchased a Geniatech ATV1200 TV Box for use as part of CarPC. Jelly Bean 4.1.2. The device is rooted.
For a car, the DPI of the screen is too low: the text is not visible at all. I'm trying to change the DPI, nothing happens. I tried the DPI changer with Google.Play, which previously worked fine on the old device under Android 2.3, it writes “successfully”, and after rebooting the device hangs on the animated logo. I tried to manually change the ro.sf.lcd_density parameter in build.prop, it does not affect anything, and in general it is initially commented out with the # sign in the file. ROMToolBox - also tried to change the screen density, it also hangs after a reboot.
I read that these programs may not correctly change the permissions on the build.prop file, so the device hangs.
When I tried DPI Changer on reboot, the logo shifted down (as it happened on the old device), i.e. their method essentially works but messes up build.prop.
Does anyone know what else needs to be changed and in what files? Or some other way to solve the problem?
Or at least how to change the font size outside the limits offered by the standard Settings utility?
Thank you.

Answer 1

Found.
There are two files in the /system/bin/ folder - set_display_mode.sh and reset_display_mode.sh . Each of them has lines:
setprop ro.sf.lcd_density 160
setprop qemu.sf.lcd_density 160
To change DPI, instead of 160, insert the desired value. Of course, in order to edit these files, first through the Root Explorer we do on the Mount RW folder.
I tried to edit these commands in build.prop before, but there was no sense. Apparently this script is run after boot and overwrites the options. Running reset_display_mode.sh changes the DPI in real time, and set_display_mode.sh changes it at boot time.

Answer 2

On some firmware, the ability to programmatically change DPI is blocked by the manufacturer. I would advise you to try third-party firmware, but I can't find anything like that :-(

Answer 3

Try another app:
play.google.com/store/apps/details?id=com.birdapi.android.dpi&hl=ru