Why does video screen get brighter and how to prevent it?

Question

This happens on Nexus 7 2013 (Google stock 5.0.2) and also happens on Galaxy Note 12.2 tablet (Samsung stock 4.4.2). I am in a dark room. I have set the system brightness to the minimum (let us call this brightness MIN). To change brightness I use swiping up/down on the left screen area.

With MX Player, when the video starts playing, even the minimum brightness (which is 0) makes the screen brighter than MIN. There seems to be no way to set the brightness to MIN. I can clearly notice that the screen has been brightened, by pressing the home button or the task switch button. I can see that the screen remains bright for about 1 second then changes back to MIN.

With VLC, when the video starts playing, if its previous brightness was 0, the brightness does not change and remains MIN. But if I change brightness once, changing it to 0 does not lower the brightness to MIN. At this point, VLC acts just like MX Player.

Is this a bug of Android? It seems as if the system passes a false minimum brightness of the hardware to the software. Is this an intended behaviour to make video brighter? Anyways, is there any way to prevent this brightness change? This hurts my eyes when I watch videos in a dark room.

==PS==

This behaviour is also happening in CyanogenMod 12 (Android 5.0.2).

Answer 1

You can disable MX Player's brightness controls. To do this, goto Settings>Player>Screen and uncheck the brightness option. And, an alternate option is to use an xposed module(you need a rooted device) named Minimum Brightness.

Answer 2

I think this could be a problem with just any video player, and not limited to the ones mentioned in the question. Also, since CM12 is mentioned, I've assumed that the device is rooted.

Note: Solution working on CM12.

I wouldn't rely or bother to change every single video player's settings I've got. If I'm in a dark room and don't want any video player to override my screen brightness setting, then I would choose Tasker to restrict brightness. This answer (by Martin J) has a mention of a location where ROMs typically saves brightness settings, and CM12 is no exception to it.

All you've to do is create some shortcuts using Tasker which would set max brightness setting (MAX) to your preferred minimum (MIN) value.

Follow the instructions

_{(In Tasker, any kind of settings are saved by pressing back button once, which would lead you to previous window as well.)}

1. Install Tasker.
2. Go to your home launcher → Widgets → choose Task Shortcut -> name the shortcut.

3. Inside Task window, create an action as Code → Run Shell, and do:

   • Command: echo 2 > /sys/class/leds/lcd-backlight/max_brightness
   • Use Root

   Change 2 to your desired MIN value. You can find out the lowest brightness value by pushing the slider for minimum brightness followed by checking the value in /sys/class/leds/lcd-backlight/brightness. It could be 10 or close to it.

4. Save it, and choose an icon for the shortcut.
5. Now the shortcut is ready for action. Whenever you're in a dark room and wanna see some video, just tap that shortcut and no player would dare to bother you again when it comes to overriding brightness setting.

Now, how would you come to back to default setting? Well, create a new shortcut with value 255 or the MAX available for your device. You can check MAX value through the method mentioned in step 3, with slider turned to maximum brightness.

This is a very simple way to deal with the issue. You can configure Tasker to change the brightness automatically if you're at certain Geographical position (dark room), or you see videos only at a certain time, and so on.

Answer 3

This is a screen filter app that I use with all my devices. Its called Darker. It has not only absolute min brightness, but it also has an option for a color as filter. Useful in low light; ie. android LED lighting is blue in light spectrum, using a red filter compensates - so eye strain is less, sleepless nights are less (my opinion and I'm not a doctor, but these are my own observations). Color and brightness filter can be used independent of each other. This can be used with or without root.

Android won't let you install apps when screen filter is active (security measure against malicious attacks), because it is an overlay on the screen.