Setting limit volume on rockbox?

[scharkalvin]

You know I think Apple was SUED by someone who claimed an ipod damaged their hearing, and I think they ended up adding something in the hw or software that limits the volume to the earphones.  Setting an upper limit would be just compare current volume setting in db to limit, if less allow increment, else stop at limit.
Two lines of C code maybe.  (but more need to build a menu to set the limit.  Still the menu could be a plugin and the limit a global byte of ram?)

Of course you could also do something similar with a battery, a resistor or two, and two back to back diodes wired in series with the earphones and the earphone jack to clip the volume at a maximum voltage level.  Maybe use Zener diodes to eliminate the battery.

In other words an inline volume control, which many headphones have.  So just set rockbox at max volume, adjust the headphone volume control to a comfortable max level, scotch tape the volume control, and then use rockbox to control volume.

[Febs]

You know I think Apple was SUED by someone who claimed an ipod damaged their hearing, and I think they ended up adding something in the hw or software that limits the volume to the earphones.

Far too much speculation here.

Setting an upper limit would be just compare current volume setting in db to limit, if less allow increment, else stop at limit.
Two lines of C code maybe.  (but more need to build a menu to set the limit.  Still the menu could be a plugin and the limit a global byte of ram?)

Why is this necessary when a total of 36dB of gain reduction can be applied via the Replaygain pre-amp and the EQ pre-cut?

[yapper]

If the 'safe listening' levels in this article (http://www.usatoday.com/tech/news/2006-03-29-ipod-volume_x.htm) can be trusted, the 36dB reduction mentioned by Febs would reduce the playback level to a 'safe' level ....
but if you are playing your music in the car, you have another amp that isn't limited by Rockbox, so there isn't going to be an absolute sure fire solution to the 'problem'.

[soap]

The sonic energy delivered to your eardrum depends on so many factors*, there is no place for blanket statements at all.  I too have seen 80-85 decibels quoted as safe...



*ear shape, headphone style (IEM, buds, supra aural, etc.), headphone efficiency, physical placement of headphone on/in ear, yadda yadda yadda

[Febs]

Also note that "safe" volume levels are measured in dB SPL (where the SPL = "sound pressure level"), which has no bearing whatsoever to the Rockbox volume scale.

[Karamelo]

It's been clear that there's no consensus so far on that particular feature request.

Yet, I think this is quite simply a *must-have*.

A couple of days ago, I've had a bad (and painful) experience while doing something apparently innocent: testing a few themes on my Cowon. As I was loading a new one, the volume suddenly jumped through the roof (for some reason, that theme contained a line "volume: 0").

Just to put things in perspective, my player's volume is usually around -60dB... You get the picture.

Anyway let alone my own misadventure, I principally disagree with Llorean about the "not turning up" solution: being portable players whose whole point is to follow the owner into the most diverse activities, there are inevitably inumerous situations where your volume control can get pressed accidentaly just when you can't get to it (and the "hold" button is no guarantee).

So, considering it as a "safety feature" with a negligible footprint, I think it should definitely be taken into account...

[Llorean]

Why not use the equalizer precut then?

Assuming the hold switch can accidentally get turned off, and the volume button can accidentally get held long enough to raise the volume to damage your hearing before your earphones can come off, and before you can stop it, the equalizer and the volume cannot be adjusted simultaneously no matter what.

Meanwhile, it such a feature would _not_ do anything about bad themes: A theme could just as easily accidentally disable maximum volume as it could change it, anyway.

[Kay]

To put this in another light, let's say there are two main volume settings I wish to use on my rockboxed MP3 player, (1) a low volume setting for headphones and (2) a high volume setting for attachment to an amplifier such as a car or home stereo through a cord.

I don't particularly care whether I have to increase the volume to get to the optimum setting for setting 2, but I do care very much if I have accidentally left setting 2 on when I wish to listen with headphones. And I don't want to sacrifice any sound quality if possible.

Is there a temporary way of increasing the volume range in order to achieve setting 2, but have it revert back to setting 1 the next time I start up the player?

I'm concerned about a youngster using my player, after I have adjusted it for playing through an amplifier. I'm also concerned about a youngster not having enough care or sense to keep the volume down. You may say, a person that young or headphone-inexperienced shouldn't have this type of sound device, but it's a common application. And the warnings on the Sansa manual I have state: "Your hearing may adapt to higher volumes of sound," leading to ever-increasing volumes. The Sansa comes with a normal and high volume setting (I assume that's a shift in upper range.)

That said, if there is not an easy way to do what is proposed, then a volume limiter override would be very nice. I assume that the precut or relay gain methods keep their settings after the unit is turned off, effectively just another volume control that can be accidentally set too high.

[Llorean]

Again, use the equalizer precut... If you put Precut settings in a file, fixed.cfg, in your .rockbox folder, they'll be re-loaded each boot. To temporarily disabled it, you just turn off the equalizer. Next time you reboot the player, the precut will once again be limiting your max effective volume.

[Kay]

With all due respect, doesn't setting the Precut high to reduce volume affect sound quality negatively? It seemed to when I tried.

[Llorean]

The precut is just a digital gain reduction. It shouldn't really sound different from simply turning the volume down.

[bascule]

Is there a temporary way of increasing the volume range in order to achieve setting 2, but have it revert back to setting 1 the next time I start up the player?

Yes. Make a copy of /.rockbox/config.cfg and rename it to fixed.cfg.
Open that file in a text editor, strip out all but the 'volume' line and set the 'volume' value to whatever you want as your volume level Setting 1 (remembering that it's in dB in the configuration file, so 0 is the loudest setting).
Re-save the file into the /.rockbox directory.
Job done!

[Angyman]

Case: User installs Rockbox for the first time (e.g. iRiver H10 Firmware)... Battery gets empty... Volume immediatly increases to maximum volume level (was/is? a bug with the iRiverH10). Something happens... Like a car accident, or a damage to the ears...

I think we are talking about a very very very important trhing: YOUR EARS...  
Yes he could read the manual, yes he could do a EQ precut, but yes maybe he didnt do both of it. And what will be if something serious happens one time?! As seen on the H10 it can happen by a malfunction by the software in combination with a specific hardware.

I think it would be on a much safer way to provide rockbox with a predefined volume limit which can be than changed by the user later on. In this case i would say that the few bytes more of code are worth it.

By the way: The only point regarding this in any place is on page 144 in the Manual saying:
THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS
WITH YOU. SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST
OF ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
 

[Llorean]

That's really impossible to do. How "loud" any given volume level is is entirely dependent upon Headphones, Player, and anything in between (amp, stereo, etc).

This means that if we pick one level, it may be too quiet to listen to on some setups, yet loud enough to damage hearing on the other.

Frankly, fixing the "Volume suddenly shoots to max" bug is a good idea, obviously. But protecting their ears is ultimately in the hands of the user, and will pretty much always have to be. You shouldn't have your headphones on when driving a car, for example.

[Kay]

Perhaps having a range of, say, four top volume ranges, so that users have a choice.

Please don't forget the case of the inexperienced or uncareful user (my example, a youngster), who may accidentally damage their ears.

Case in point, as I was exploring the precut EQ, I had the volume set up to top level to see what the highest level of precut would achieve and whether the sound quality was diminished. Since the precut can be adjusted while music is playing, a simple down cursor press on the Toshiba Gigabeat crosscontrol raised precut from the highest to 0 level. Had my headphones been close to my ears I could have damaged my ears while testing the very feature that has been put forth as the solution.

I may not have been clear enough in previous post, but the two preferred states for me would be a volume limited range and non-limited range, and reversion back to the volume limited range. The volume setting proposed in a previous post to the CFG file wouldn't help this; the setting to the precut would, assuming there's no reduction in quality.