Backlight

[darren89]

Is there a way to reduce the brightness of the screen on my 80gig ipod? Have searched the manual and can't a solution.

[LambdaCalculus]

No, there isn't. Not officially, anyway.

[cool_walking_]

There is a patch for controlling brightness. I don't know if it works, but it's here.

To use it, you will have to set up a development environment with Cygwin, VMware, or Linux.

Then read How To Compile and Working With Patches.

[GodEater]

Or find an unsupported build which already includes it.

Note the word "unsupported" means what it says though. The only support you'll get is from the build author.

[darren89]

What about those daily/current builds? They seem to keep updating, but do any of them fix the problem?

[GodEater]

No - because they don't include the patch.

[soap]

What about those daily/current builds? They seem to keep updating, but do any of them fix the problem?

Assuming there is a problem.

The patch in question "dims" the backlight by flicking it on and off very rapidly.  How good this is for the hardware I can't say.

[psycho_maniac]

does this flickering reduce battery life at all?

[DefineByte]

Not that I've noticed but I don't think any measurements have been taken.

[Yotto]

I have used the patch in various unofficial builds, and can guarantee that it lowers battery drain on iPods.  I have not run any tests for actual numbers (But I may), but at a level of "5" (The lowest level that doesn't obviously flicker) I can leave the backlight on and plugged in, and the battery actually gains charge over time.  With the backlight on full, plugged in, my iPod loses charge.

Maybe tonight I'll run some tests and listen to the music on my hard drive for a change, assuming it would help the adoption of this patch (which it may not, if the concern is that the flickering is doing damage to your player.  I have no way of determining that, but have been using a level of 5 since the first unofficial patch allowed it).

[DefineByte]

Even if the method of brightness reduction itself was accepted, the patch isn't in a state that would be committed.

[soap]

...help the adoption of this patch (which it may not, if the concern is that the flickering is doing damage to your player.  I have no way of determining that, but have been using a level of 5 since the first unofficial patch allowed it).

Let me make clear I wasn't trying to imply that this patch was doing harm to your player.  I simply don't know.  The general idea is valid - I just don't know if this implementation is.

[Yotto]

Sorry, I wasn't implying that anything was implied, and when it comes to the coding I'm not really in a position to say anything either way.

When I go to sleep (in a couple hours) I'll leave my iPod on, with the backlight on level 5.  I'll have it playing (Can't fall asleep without the music) but won't turn the sleep mode on, I'll let the battery drain on its own with the meter running.  Then, tonight, I'll charge it and tomorrow do the same thing but with the backlight off.

I'll post both logs tomorrow.  Whether it helps or not, I'm curious and figure others could be as well.  The difference may not be that much, just enough to cross the slow charging threshold.

[scharkalvin]

Turning the backlight on and off at a rapid rate is a form of pulse width modulation.  By doing this you vary the duty cycle of the light and therefor it's apparent brightness.  Doing this can't hurt an LED backlight, but it might shorten the life of an el panel (depending on the inverter used to supply hv that these panels need).  It also shouldn't hurt a transistor used to switch the power to an LED backlight, but again in the case of an EL panel where the inverter could generate a back emf it might.

Bottom line.... If the backlight is LED I would not worry.  IF the backlight is an EL panel, there could be a hw problem.

[Yotto]

Note: This is with an unofficial build, because the test is impossible to do with a daily build and it deals with what we are talking about (the backlight). Also, I am comparing it to other runs done on the same unofficial build and not comparing it to other runs done on other builds.

Here's the results from the backlight off, on level 5, and at full (Level 15); and the volume on -30db, continuously playing a shuffled set of 5 ~30meg, ~30 minute podcasts of sleep-inducing music.

Backlight on level 15 (Maximum)
Backlight on level 5
Backlight off

Due to me being lame, 2 of these start at about 90%, so I'm only counting from there to 0 on all 3.
"level0" took 6:55 hours to go from 90% to off.
"level5" took 6:00 to go from 90% to off.
"level15" took 3:10 to go from 90% to off.

So, the backlight on level 5 eats up about 1 extra hour per 7, and the backlight on full eats up over half the battery.  Plus, level 5 is much easier to look at, especially in the dark.  I'd forgotten how blazingly bright the full backlight was until I did this test.