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Rockbox General => Rockbox General Discussion => Topic started by: VietPho on October 20, 2006, 03:37:00 AM

Title: Setting limit volume on rockbox?
Post by: VietPho on October 20, 2006, 03:37:00 AM
Sigh... 2 weeks ago I accidently put the volume of my 60 gb ipod video rockbox to the max and I killed my Ipod headphones :(
I just bought the Creative EP-630 for 28$ off Amazon and it would suck if I accidently blow out my new headphones.

My question is how do I set a limit to volume for my rockbox? I was able to do it on apple original firmware, but I can't find out how to do it on rockbox.
Title: Re: Setting limit volume on rockbox?
Post by: Genre9mp3 on October 20, 2006, 06:46:38 AM
I don't think there is a setting anywhere to set a "volume cap" or something, but I think this would be a nice thing to have. Maybe you can add this to feature requests in the tracker. On a side note, I wouldn't worry to blow out my headphones but I would worry for my ears. ;)
Title: Re: Setting limit volume on rockbox?
Post by: Llorean on October 20, 2006, 06:47:54 AM
You can always set the precut in the graphical equalizer menu. For all practical purposes it's a similar idea.
Title: Re: Setting limit volume on rockbox?
Post by: Genre9mp3 on October 20, 2006, 07:18:51 AM
You can always set the precut in the graphical equalizer menu. For all practical purposes it's a similar idea.

Isn't precut just adjusting the overall gain of the EQ? Surely though, you could end up to a similar functionality by setting a negative precut value so even max volume wouldn't be so loud. But you should have the EQ enabled for that (extra CPU load) and I don't think that it's a similar idea to just set a volume cap somewhere in the settings (eg. -20 dB) so the user won't be able to go further than that.
Title: Re: Setting limit volume on rockbox?
Post by: pabouk on October 20, 2006, 07:37:32 AM
Other disadvantages of using the precut setting:
- the signal will be digitally attenuated - so your S/N ratio will be lower (lower audio quality)
- the volume dB scale will be shifted
Title: Re: Setting limit volume on rockbox?
Post by: Llorean on October 20, 2006, 08:16:57 AM
But the *advantages* are:

- Does not increase binary size at all beyond current.

Seriously, I don't think it's worth wasting any binary size on an option that simply prevents user error, especially when there are very similar functions that can be achieved using both the equalizer and replaygain (though not ideal, at least they don't increase the binary size any since they're already there).
Title: Re: Setting limit volume on rockbox?
Post by: L on October 20, 2006, 08:22:59 AM
If you get proper earphones, they wouldn't blow that easily.
Title: Re: Setting limit volume on rockbox?
Post by: Genre9mp3 on October 20, 2006, 08:34:43 AM
But the *advantages* are:

- Does not increase binary size at all beyond current.

I disagree with that point because I don't think that adding such an option will increase the binary size so much that we have to worry about. Sure, binary size is an important factor to take into account but so many features are being added into CVS in daily basis and increase the binary size much more than this feature would.

And to quote LinusN from yesterday's logs:
Quote
let's just stop adding features to rockbox - the binary size is too big
Title: Re: Setting limit volume on rockbox?
Post by: Llorean on October 20, 2006, 08:36:28 AM
Yes, *features* are being added. Things that cannot be done without adding code.

Volume limiting can be done without adding code by a user not increasing the volume.

Saying "it's small" means nothign. It still increases the code size for very very very little added gain.
Title: Re: Setting limit volume on rockbox?
Post by: Genre9mp3 on October 20, 2006, 08:52:26 AM
Volume limiting can be done without adding code by a user not increasing the volume.

Actually this is not a volume limiting feature, it is a "user error" prevent feature, and I _do_ think that such features are worth adding.

Some may find this feature handy, others may won't gain anything from it and never use it (I never experienced such a problem, so I can say that I wouldn't gain for it) but I don't think that we shouldn't add features to conserve binary size at a small size.

We just see it differently... You see it as a "very very very little added gain" feature while I see it as a "very very very little binary size increase" feature
Title: Re: Setting limit volume on rockbox?
Post by: Llorean on October 20, 2006, 08:55:01 AM
Yes, but here's the deal: The more very very very littles you add in, the bigger the binary gets.

It's already officially "too big" (rombox doesn't fit) and this is a feature that if included should go to all targets. How little the size is doesn't matter, if it increases the binary at all. You weigh that something is added vs how beneficial it really is, and to me this doesn't seem like something that benefits Rockbox as a whole. It makes the binary bigger for everyone who doesn't use it, makes it harder still to get Rombox down to a usable size, and benefits a very small number of people who for some reason can't be bothered to check their volume levels.
Title: Re: Setting limit volume on rockbox?
Post by: Genre9mp3 on October 20, 2006, 09:01:55 AM
I agree. We just weigh it differently.

I'm aware of the rombox problem, but this is something that needs to be handled in a different way otherwise we won't be able to add new features anymore.
Title: Re: Setting limit volume on rockbox?
Post by: Llorean on October 20, 2006, 09:06:24 AM
I just don't want features that only provide seem to be beneficial to those who can't be bothered to pay attention to have a negative impact on everyone else's battery life.

A whole host of minor "safety" features could be added (more confirmations on things like file overwrites, automatic precut setting in the equalizer, etc, etc) each "very small" and each slightly decreasing the battery life of everyone who's willing to actually take care of those settings themselves.

Replacement firmware is not something to enter into lightly anyway, and I don't see all this fluff as being beneficial to a user who actually cares about what he's doing, meanwhile it does have a negative effect (albeit small, but cumulative) on all the users who have no use for such fluff.

So, that's why I put such a strong negative weight on what seems like such a minor feature. In the case of any small thing, it can be considered "minor" but at the same time, once it's in, it's *VERY* hard to remove it without huge amounts of objections, so it's better to say "Is this valuable enough to sacrifice something else for later?" and in my opinion it's very certainly not.
Title: Re: Setting limit volume on rockbox?
Post by: Genre9mp3 on October 20, 2006, 09:17:59 AM
Though I can clearly understand your point of view on this in general, I can't understand how an extra setting can decrease battery life.
Title: Re: Setting limit volume on rockbox?
Post by: Rincewind on October 20, 2006, 09:18:55 AM
I don't think that the binary size killer argument should be applied to such a small feature.

perhaps this could be done with only 2 lines of code - just an "if statement" in the right place (plus the menu option to set it, which should be small with the new settings system, too).

recently the last.fm log got commited - I would call that feature a binary size waste.

Every serious software tries to protect users from damages to their health. Btw. I think that Jonathan Gordon's idea to set settings to always start at a default value when starting the player is more useful than an overall volume limit, because I want full volume when I use line-out and the accidential risk of full volume is only there when you start the player and don't know where it was when you shut it off the last time.
Title: Re: Setting limit volume on rockbox?
Post by: Llorean on October 20, 2006, 09:22:57 AM
Increasing binary size decreases RAM available for the audio buffer which decreases battery life. This effect is most noticeable on the Archos players where even a small decrease in buffer can have noticeable effects, and is much less notable on the software codec targets but still a concern.

I think having an autoload.cfg file where you can set the volume (rather than having it preserved across boots) is a better solution, as this provide a lot more useful functionality as well (if you change settings for your car, you'll know they'll always restore to earphone settings on a reboot, or whatnot).

The binary size argument *must* be applied to ALL features. I don't know if you were around for the volume scale change from % to dB. At that time, MANY people objected. And it would be trivial to have an option to display volume in the old way, as %, on the status bar to go alongside the dB scale, but that tiny amount of code was deemed to be not worth it, as it provided no real functionality or benefit. I see the limited the same way. It's tiny, but it's fluff as all it does is something that is for most users useless, and for those few users it affects something that can be avoided by simple use of their brain and hands.

While the audioscrobbler support is *much* bigger in binary size increase, it's also something that can't simply be accomplished otherwise (other than by tracking listening habits on a sheet of paper and typing up the log, something well outside of 'reasonable').
Title: Re: Setting limit volume on rockbox?
Post by: bascule on October 20, 2006, 09:40:50 AM
I think having an autoload.cfg file where you can set the volume (rather than having it preserved across boots) is a better solution, as this provide a lot more useful functionality as well (if you change settings for your car, you'll know they'll always restore to earphone settings on a reboot, or whatnot).
Absolutely. This would be really useful functionality and it is implemented using existing functionality (loading a config file).

You could set just the volume, or put in the whole gamut of settings...

...audioscrobbler...it's something that can't simply be accomplished otherwise...

True, but for my money, this is absolute fluff. How is uploading runtime db info to a third party website more 'beneficial' than core audio playback and information functionality?

Could the audioscrobbler patch not have been implemented as a plugin or even an external app querying the Tag Cache database when the player is hooked up to a PC?

I know we're slightly OT now, but maybe the easiest solution to the Archos problem is an optimised Release 3.0 containing a whole load of the most recent enhancements and then accept that anything after that may have to be hand-crafted by removing features and re-compiling?

This would leave the field open for less constrained development for the more powerful targets.

The messy solution, of course, is a code fork, allowing the colour/video/fluff/PDA/etc. targets to go their own way, and keeping a tight version for the audio-only/constrained targets.
Title: Re: Setting limit volume on rockbox?
Post by: Llorean on October 20, 2006, 09:45:31 AM
I'm not defending the way it was implemented. I personally think it's fluff as well. But actually, as an external app or plugin it wouldn't be able to offer the same functionality if my understanding is correct.

What it currently does, to my understanding, is log songs as you play them. An external app or plugin would have to compare the database to a copy of the database representing what it was the last time logging occurred and generate a log based on that, which would then become impossible if you were running the app from a different computer, or if the runtimeDB had to be regenerated, or any of a host of other reasons.

But this topic is not about Scrobbler support at all.
Title: Re: Setting limit volume on rockbox?
Post by: Genre9mp3 on October 20, 2006, 09:57:40 AM
Increasing binary size decreases RAM available for the audio buffer which decreases battery life. This effect is most noticeable on the Archos players where even a small decrease in buffer can have noticeable effects, and is much less notable on the software codec targets but still a concern.

True but unreasonable and excessive for the feature we are talking. The difference would be way far from noticable even on a HDD Archos player. But as I said, I understand your point of view.
Title: Re: Setting limit volume on rockbox?
Post by: Llorean on October 20, 2006, 09:59:38 AM
The point isn't that *this* feature would be noticeable. The point is that there are many many "very small" features out there, and they would add up. Is a volume limiter more useful to you than a second option in Volume display that's %? Because we had a *lot* of people who wanted that back when we changed it.

Or since they're both 'very small' we could add both... but eventually it adds up, and it's better to try not to add things in advance if they don't actually *add* something anyway.
Title: Re: Setting limit volume on rockbox?
Post by: Genre9mp3 on October 20, 2006, 10:10:28 AM
Yes... so this leads us back on how someone weighs the benefit of a feature. And I still think that this feature adds something even if I don't actually need it myself. I must agree though that the autoload.cfg idea would be better to have.

So I guess, that's probably the benefit of arguing about functionality :)
Title: Re: Setting limit volume on rockbox?
Post by: Rincewind on October 20, 2006, 10:16:20 AM
The point isn't that *this* feature would be noticeable. The point is that there are many many "very small" features out there, and they would add up. Is a volume limiter more useful to you than a second option in Volume display that's %? Because we had a *lot* of people who wanted that back when we changed it.

Or since they're both 'very small' we could add both... but eventually it adds up, and it's better to try not to add things in advance if they don't actually *add* something anyway.

As I said, the limit can be accomplished with the autoload feature. It seems to me that you don't object to that. So I would say that a better way to settle an argument over a feature request is to turn the request into something more general that we can all consider useful.

I was around when the db change came up and found the whole argument funny and entertaining because I couldn't care less. But it also shows that many people (especially non-developers) care about things that we (If you don't object that I call myself a developer here) don't consider to be important.

Maybe important isn't the right word here, but don't know how to describe my thoughts in english better.
Title: Re: Setting limit volume on rockbox?
Post by: Llorean on October 20, 2006, 10:18:55 AM
I just see the volume limiter as a "convenience" instead of a feature, since a human can easily limit the volume by simply not turning it up.

And in my mind that makes it very difficult to justify, independent of size.

I can easily see how it would be important to some people, but I really don't understand why those people find it so difficult to not turn up the volume. I guess that's my problem, that I can't see their point of view at all.
Title: Re: Setting limit volume on rockbox?
Post by: Genre9mp3 on October 20, 2006, 10:31:57 AM
I can easily see how it would be important to some people, but I really don't understand why those people find it so difficult to not turn up the volume. I guess that's my problem, that I can't see their point of view at all.

This is why I consider that this feature/convenience/whatever would "add" to the project. From my point of view, if some users find important something, then this worths to be added (as long as it doesn't add any reasonable disadvantages). It's just how I see Rockbox. Functionality that you can't get with retailOS.
Title: Re: Setting limit volume on rockbox?
Post by: baobab68 on October 20, 2006, 10:43:44 AM
If I might add my 2c?

I am very conscious of protecting my hearing, and always *try* to keep the volume low as possible.

But:

- the player is in my pocket and I can't read the volume level
- I can't resist turning it up when the best part of a song comes on!

I don't know the overall status of the project etc though, as the other participants in this thread do, but as a user I know that I am a sucker for a good song..!
Title: Re: Setting limit volume on rockbox?
Post by: saratoga on October 20, 2006, 11:27:14 AM
I don't see the point of argueing about this.  If someone wants the feature, let them create a patch for it, then we can evaluate the patch and decide if its worth including, or if we should just make it an optional feature for 3rd party builds.
Title: Re: Setting limit volume on rockbox?
Post by: lowlight on October 20, 2006, 11:47:00 AM
There's acutally a dangerous bug in the volume menu...the list wraps allowing you to go from min->max.  Since the volume updates as you scroll, be careful :o
Title: Re: Setting limit volume on rockbox?
Post by: gorman on November 13, 2007, 05:58:02 AM
I just see the volume limiter as a "convenience" instead of a feature, since a human can easily limit the volume by simply not turning it up.

And in my mind that makes it very difficult to justify, independent of size.

I can easily see how it would be important to some people, but I really don't understand why those people find it so difficult to not turn up the volume. I guess that's my problem, that I can't see their point of view at all.
Hi! I'm resurrecting this thread after using the search feature on the forums, looking for just this function.

I have a rockboxed Gigabeat and I believe that for certain targets this function could be more important than for others. On the Gigabeat it's entirely too easy to raise the volume by mistake, considering it's bound to the up/down commands on the touch-sensitive cross. It happened to me the other day and I risked seriously damaging my hearing.
It probably might be easier to take away volume control from the cross, as I mentioned somewhere else, but I just wanted to point out that it's not just a matter of "it's not tough not to turn up the volume".

Cheers!
Title: Re: Setting limit volume on rockbox?
Post by: JeoL on November 13, 2007, 06:50:05 AM
As a user who is prone to making mistakes, I think this option would be very good.
Title: Re: Setting limit volume on rockbox?
Post by: Febs on November 13, 2007, 06:55:44 AM
You can achieve a similar result in Rockbox right now by using the ReplayGain pre-amp and Equalizer pre-cut settings.
Title: Re: Setting limit volume on rockbox?
Post by: scharkalvin on November 13, 2007, 02:13:15 PM
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.
Title: Re: Setting limit volume on rockbox?
Post by: Febs on November 13, 2007, 02:25:30 PM
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.

Quote
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?
Title: Re: Setting limit volume on rockbox?
Post by: yapper on November 13, 2007, 09:14:11 PM
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'.
Title: Re: Setting limit volume on rockbox?
Post by: soap on November 14, 2007, 05:48:47 PM
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
Title: Re: Setting limit volume on rockbox?
Post by: Febs on November 14, 2007, 05:53:55 PM
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.
Title: Re: Setting limit volume on rockbox?
Post by: Karamelo on November 18, 2007, 09:48:36 PM
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...
Title: Re: Setting limit volume on rockbox?
Post by: Llorean on November 18, 2007, 10:40:36 PM
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.
Title: Re: Setting limit volume on rockbox?
Post by: Kay on November 29, 2007, 12:46:15 AM
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.
Title: Re: Setting limit volume on rockbox?
Post by: Llorean on November 29, 2007, 12:49:41 AM
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.
Title: Re: Setting limit volume on rockbox?
Post by: Kay on November 29, 2007, 12:53:06 AM
With all due respect, doesn't setting the Precut high to reduce volume affect sound quality negatively? It seemed to when I tried.
Title: Re: Setting limit volume on rockbox?
Post by: Llorean on November 29, 2007, 12:55:04 AM
The precut is just a digital gain reduction. It shouldn't really sound different from simply turning the volume down.
Title: Re: Setting limit volume on rockbox?
Post by: bascule on November 29, 2007, 03:58:08 AM
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!
Title: Re: Setting limit volume on rockbox?
Post by: Angyman on November 29, 2007, 04:18:36 AM
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.

 

Title: Re: Setting limit volume on rockbox?
Post by: Llorean on November 29, 2007, 10:09:58 AM
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.
Title: Re: Setting limit volume on rockbox?
Post by: Kay on November 29, 2007, 07:46:49 PM
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.
Title: Re: Setting limit volume on rockbox?
Post by: Llorean on November 29, 2007, 07:52:26 PM
Frankly, a maximum volume limit won't stop an uncareful user. If it doesn't get loud enough, they'll look for something to disable so that they can get it louder.

I understand trying to limit it to prevent accidents, but if you teach someone to be careful about their hearing, and they consciously choose to disregard you, as long as the option's there there's a good chance they'll find it.

I still don't understand, what exactly is the problem with using Precut? And if you haven't established a problem with precut, why are we continuing this conversation at all, since it does everything you've asked so far?
Title: Re: Setting limit volume on rockbox?
Post by: safetydan on November 29, 2007, 07:57:27 PM
@Kay, that particular bug of the precut setting wrapping around should be fixed in the latest builds.
Title: Re: Setting limit volume on rockbox?
Post by: Kay on November 29, 2007, 08:14:19 PM
@Kay, that particular bug of the precut setting wrapping around should be fixed in the latest builds.

That answers one of my concerns. The user I have in mind wouldn't go into advanced settings to defeat the volume limiting range, but *would* possibly set the top volume higher than it should be - say, a 10 year old. Perhaps they're too young for some players.

I remember Sony had a volume limiting range (maybe European models) that savvy users soon discovered how to defeat. Fine, they should be able to...but a parent might not want to do that for their child's system.
Title: Re: Setting limit volume on rockbox?
Post by: yapper on November 29, 2007, 08:21:38 PM
I believe the solution lies outside of Rockbox, as the sound pressure level experienced by a user will be a combination of the electrical gain (controlled by the firmware) and the sensitivity of the headphones being used.

Acoustic shock prevention in telephone systems is partially controlled by network gain plans, but increasingly through the use of headsets which have built in protection. (Google 'acoustic shock' for more on this)

I'm not aware of any headphones for music players which claim to have 'protection' , but a simple solution might be to use some less efficient headphones than the standard ones. This will limit levels with Rockbox or the OF, but obviously it doesn't take much to plug in a more efficient set of headphones if someone wanted to bypass the 'protection'.
Title: Re: Setting limit volume on rockbox?
Post by: safetydan on November 29, 2007, 08:22:33 PM
So what concerns do you have remaining? The precut will limit the volume in the way you desire. It's a setting buried sufficiently far down the menu hierachy that you won't accidentally undo it. And it now won't wrap.
Title: Re: Setting limit volume on rockbox?
Post by: Kay on November 29, 2007, 08:43:14 PM
I'm good...I'll likely use a headphone that has an inline volume control, then duct tape the volume at somewhat below top level, and not use the precut. That way, if I plug into the amplifier (car stereo), the volume won't be limited. Not very elegant, but it will work. Thanks, safetydan and all.
Title: Re: Setting limit volume on rockbox?
Post by: safetydan on November 29, 2007, 08:56:47 PM
As a last word, if you're concerned about kids setting the volume too high try googling for "kid safe headphones".