In this case, VLC just uses the Windows APIs (DirectSound), and sends signed integers of 16bits (s16) to the Windows Kernel.
VLC allows amplification of the INPUT above the sound that was decoded. This is just like replay gain, broken codecs, badly recorded files or post-amplification and can lead to saturation.
But this is exactly the same if you put your mp3 file through Audacity and increase it and play with WMP, or if you put a DirectShow filter that amplifies the volume after your codec output. For example, for a long time, VLC ac3 and mp3 codecs were too low (-6dB) compared to the reference output.
At worse, this will reduce the dynamics and saturate a lot, but this is not going to break your hardware.
VLC does not (and cannot) modify the OUTPUT volume to destroy the speakers. VLC is a Software using the OFFICIAL platforms APIs.
The issue here is that Dell sound cards output power (that can be approached by a factor of the quadratic of the amplitude) that Dell speakers cannot handle. Simply said, the sound card outputs at max 10W, and the speakers only can take 6W in, and neither their BIOS or drivers block this.
And as VLC is present on a lot of machines, it's simple to blame VLC. "Correlation does not mean causation" is something that seems too complex for cheap Dell support...
Maybe Dell should advise against playing Metal music and should only allow Céline Dion music, because Metal saturates more...
EDIT: more details...
PS: they even provide a BIOS update for the fix... So, of course, VLC was the issue... http://www.dell.com/support/troubleshooting/us/en/04/KCS/Kcs...
>VLC does not, and cannot modify the OUTPUT volume to destroy the speakers.
That would be remarkable.
>And as VLC is present on a lot of machines, it's simple to blame VLC. "Correlation does not mean causation" is something that seems too complex for cheap Dell support...
It sounds like a #BOFH excuse.
The problem is it's too easy to set the volume above 100%. I've done so with the mouse wheel. And I now have a $2000 out-of-warranty laptop with blown speakers.
Fixes could include:
* Not remember settings above 100% between sessions unless an advanced option is checked that warns the user.
* Require a double click on volume slider to go above 100%.
VLC's high volume is a wonderful feature when you're listening to DTS or AAC movies encoded with the volume too low. It's just too easy to be accidentally abused.
Your computer was defective, and Dell is refusing to comply with the warranty. It's impossible for VLC to harm the speakers on a computer that is not defective.
Ok, I like it being hard to set volume bigger than 100% at mplayer, it'll probably be a nice feature at VLC. But that's only because I don't like clipping, not because of any hardware issue.
That makes a lot more sense than force software to not do something it can and should do "just in case Dell failed at their job".
You can view PCM sample amplitude as telling the sound card how much power to apply to the circuit driving the speaker. A large amplitude means the speaker cone should move a lot, and small amplitude means it should stay nearly at rest.
So that means that the sound card has to interpret each of the signed 16-bit values and determine what kind of electrical signal it should output to the speakers to get the desired effect (sound). A sample with the highest signed 16-bit value (32,767) tells the sound card to produce its most powerful signal.
Now, in a laptop, the sound card and speakers are chosen by the manufacturer. Different sound cards can produce varying amounts of output power, and different speakers can handle varying amounts of input power. Obviously the speakers need to be chosen such that the sound card cannot produce more power than the speakers are rated to handle. (It sounds like Dell made a design error here.)
If the sound card and speaker choice is such that the speakers cannot handle the sound card's output power, then any audio software that produces signed 16 bit samples above some threshold (let's say 32,000) could damage the speakers.
So what audio software could produce such large amplitudes? ANY SOFTWARE AT ALL. Not just VLC. I could create a .wav file that was just a bunch of loud noise with amplitudes above 32,000, and it would destroy your speakers.
In fact, most well-mixed sound files will have at least one sample at the maximum amplitude. This is called normalization -- to provide the highest fidelity sound, you want to use the entire dynamic range of the PCM sound format, and thus ideally the loudest bit of the track should be exactly at 32,767. Lots of modern music uses a technique called compression ("dynamic compression," not to be confused with data compression) to make good use of the full dynamic range of PCM, which results in LOTS of samples at or near the maximum level.
On a correctly designed audio system, this is great! You get to hear audio with the fullest dynamic range that your equipment can produce. If your system has been designed incorrectly, though, you'll blow out your speakers. But that could happen due to ANY SOFTWARE AT ALL, not just VLC.
If you really want to buy crappy Dell hardware and not blow out the incorrectly designed audio system, you should permanently decrease your global Windows volume level. That will put a hard cap on the PCM amplitude levels sent to the sound card, and thus will cap how much power is sent to the speakers.
Blame Dell. VLC has exactly nothing to do with your problems. The "volume above 100%" feature is not dangerous on a properly designed audio system (like 99.99% of computers out there).
"Be aware that just having Youtube in your browser history is enough to deny your warranty."
Porting it to Web Audio API is left as an exercise for the reader.
Is this claim actually true?
My understanding is that if you take a waveform and clip it, the resulting waveform actually carries less energy (think of the corresponding integral), but more of that energy is pushed into the higher frequencies. It's this – the unexpectedly large amount of high-frequency energy – that kills speakers because their crossover networks push it into the tiny, tiny tweeters, and they are utterly unprepared for it.
> Is this claim actually true?
Yes, it is -- but it depends on how we define "clipped".
> My understanding is that if you take a waveform and clip it, the resulting waveform actually carries less energy (think of the corresponding integral)
Only if the clipping reduces the peak value. If you compare a sinewave with a peak value of 1, and a square wave with a peak value of 1, the square wave has a substantially higher average level (with a ratio of pi / 2).
> It's this – the unexpectedly large amount of high-frequency energy – that kills speakers because their crossover networks push it into the tiny, tiny tweeters, and they are utterly unprepared for it.
Yes -- the rate at which the speaker cones are required to move is an additional factor. But for a "clipping" definition that clips by means of trying to exceed the available voltage, these two effects add.
http://i.imgur.com/oE5NFZ9.png
In the above linked image, the red trace is sin(x), the integral for the interval 0 < x < pi is 2. The green trace produces an integral of pi. The ratio of the two is pi/2, and the speaker power difference is (pi/2)^2 = 2.46 (because the speaker's power is the square of the applied voltage).
The green trace is what you would get if you simply turned up the volume beyond any reasonable setting -- the amplifier produces a clipped version of the sine wave and the peak value is equal to the supply voltage.
This is why distorting the amplifiers (especially digital clipping) is so much worse for speakers than overpowering the speakers. This is a very well known fact in audio circles.
Playing metal at full volume is not as damaging as playing anything intensely digitally clipped at full volume.
Yes, Dell is putting on shitty speakers on their laptops, (what else is new), but VLC should be amplifying the output using level-limiting (hard-limiting), which would effectively bring all the quiet parts to be just as loud as the loud parts, instead of just digitally clipping the output.
I have to say, there may be a UI issue here as well. I blare my speakers with VLC playback something like 5X times more often than QuickTime player or mplayer. I use all 3 with about equal frequency.
This is correct, and for those who want to know the technical reason, we can look at the Dell speakers (any speakers) as a resistive load (only approximately true). For a resistive load, the power increases as the square of the applied voltage, because the power in a resistor is equal to the voltage times the current, and both the voltage and current are increasing as the audio output level is increased.
In terms of Ohm's Law: P = E^2/R.
I am a VLC fan (thanks! I wish I was skilled enough to contribute to the project) and right now using a ASUS laptop, I want to know what manufacturers I should NOT buy from next time (I bought this ASUS because I tried to buy from DELL and their site was buggy and did not closed the transaction... good to me their site was buggy!)
We heard about HP and Dell doing that, and ONLY in the version they shipped to India or South-East Asia (Do they ship worse components there?)
> I wish I was skilled enough to contribute to the project
There is a very high chance that you are skilled enough, to be honest.
There is actually a chance that they might be, considering not all models are available in all regions, thus there are models that are marked for South-East Asia. So as a manufacturer, it's relatively easy for them to be biased.
That said, vendors in South-East Asia have a history of being scammers and taking out original parts and replacing them with cheaper hardware, so that could be a cause too, and HP might be innocent.
The thing about this is that such behavior makes sense when the suppliers are integrators of the product of twenty or fifty or however many suppliers spread around the globe all relentless trying to cut costs (including cutting corners in implementing whatever spec their chips are supposed to satisfy). The integration itself naturally involves putting together the cheapest stuff and seeing-if/hoping-that it will work. So when you have such a fragile chain of elements, just blank-refusing to allow substitutes makes sense in this rather twisted view. Maybe Windows Media Player fails to call the parts of the API that are "bad" and not documented as bad.
Obviously, I'm not saying this approach is justified, simply that sometimes the irrationality is "sincere".
I'd prefer to be warned rather than surprised by this!
Maybe Microsoft could regulate the output for junk speakers, but really, Dell is the one to blame here.
This is what MS Office does. A Microsoft engineer told me once that because many printers lie to the OS about their capabilities, they built a giant lookup table into the Office, that basically consists of "if printer model X, vendor Y and firmware Z, then don't trust it about the fonts onboard, render the text before sending instead".
The problem is simply that the Dell speakers are piles of shit.
How would you do that?
And no, this is not specific to VLC.
In other words, due to increase in amplitude, increasing volume over 100% can break the hardware? I am not trying to blame VLC, just that your statement "At worse, this will reduce the dynamics and saturate a lot, but this is not going to break your hardware" sounds a bit fallacious in the context of your own explanation.
Sad to see behavior like this
And here in India I hear people say that you shouldn't install VLC on laptops .. (even if its not a Dell laptop) !!
But does anyone have list of Manufacture that does provide speaker with BIOS Protection?. Does Apple do?
well I guess their support people are not engineers, only technicians, hope this blows back into DELL PR instead...
Indeed, and doing that destroys audio equipment just as effectively. It's the reason apps like SoundForge, Audacity and others have clip warnings on their level monitors: so users don't create audio data that destroys listeners' equipment.
The problem is VLC gives consumers (who, like you, don't know better) an exceptionally easy way to create clipped audio. Depending on the characteristics of the source, the degree of clipping VLC can create can destroy even pro equipment. If I were an engineer at Dell, I'd recommend denying warranty claims too.
There is no excuse, none, nada, zip, zilch, in 2014 for allowing userland software to generate signals powerful enough to damage built-in hardware.
If the speakers in a consumer device like a laptop can be damaged by maxing the volume then the laptop was not properly designed. This isn't a case of a nutty audiophile mixing and matching unknown preamps, amps, and speakers and managing to blow some cones by cranking it to 11. Dell has complete control over the selection of components in this laptop and, if they cared to, could include circuitry to limit power beneath a point that will damage the speakers. They didn't. Alternatively, they could eschew a limiter and select speaker components beefy enough to handle the maximum voltage that their DAC's can output. They didn't. Bad design.
If Dell did the math and decided the number of users noticing permanent speaker damage would be small enough that the reduced part costs would outweigh the price of the resulting warranty service, that's their decision. However, they should be on the hook to fix damaged caused by their cheap/poor design.
On the other hand, a movie with lots of low frequency content (explosions and stuff) whose audio is clipping will damage the small full range speakers since most of the audio energy is concentrated at the very low frequencies (where the signal has a lot of power) and the peaks are long.
Or a multi-band limiter for the explosions.
Companies like to talk about "voiding the warranty" for all kinds of stupid stuff, and consumers don't know their rights so they often get away with it, but what the law allows is considerably more constrained.
Ok enough metaphors.
It's possible, however, to create raw PCM that will destroy a lot of consumer equipment if played long and loud enough. VLC basically gives consumers a way to do that and labels it a feature.
Not so fast, I see no car metaphor yet. And there is no comparison of Dell's practices to those of Hitler or the Nazis, either. We are far from 'enough' metaphors, my friend.
Imagine if this was some crazy keyboard which could actually press keys automatically using a motor. Then imagine if the drivers and hardware allowed you to destroy the keyboard by pushing the motor too hard. This would be obviously crazy and the ability to write userland software that destroys built-in hardware should not result in a denied warranty.
But when you're buying them in quantities that a company like Samsung would (that above link is, amusingly enough, to ones that Samsung themselves make), the price drops off rather steeply. $0.001USD is around what I can find for buying them from China in 100Ku.
If Dell doesn't build audio properly, how can they blame the users? They really have some gut...
The VLC volume control has always terrified me, I wish it would have AGC or at least a soft limiter when pushed above 100%. I've seen people watch films with it cranked up to 200% and the system volume turned down to compensate :(
Since then I have vowed never to buy Dell.
If Dell said VLC was installed so warranty is void, I'd say I want the computer fixed as a "reklamasjon"-case, and so they can't hide between stupid rules like this. This also means that we are allowed to swap RAM, CPU's etc. in our computers without fear of not getting the computer fixed if it later breaks down for unrelated reasons.
I don't think it is a wild compromise to make some assumptions about the sounds people will play through the speakers (and it's not like a spec relating the max energy/time is going to help most shoppers).
Anyway, a moderator from Dell replied that you can contact him if Dell refuses to give support just by seeing VLC installed, so maybe it's better than it seems.
(But I don't think it is obviously unreasonable to sell a cheap laptop with cheap speakers, configured to be able to make louder peaks)
Speakers shouldn't melt because of software (unless there is dodgy firmware.)
Actually, speakers are speced in terms of RMS wattage...which is exactly that.
http://secunia.com/advisories/52956/
http://secunia.com/blog/shooting-the-messenger-372
http://it.slashdot.org/story/13/07/10/1520245/vlc-and-secuni...
I have tried to update VLC Media Player on one machine on my home network, and the update fails, suggesting that the VLC Media Player installation on that computer may already be compromised by malware (which has previously been detected on that machine). What is the recommendation for current VLC Media Player users to make sure that they have a recently updated, reasonably safe installation of VLC Media Player that doesn't open up their computer to other vulnerabilities?
We did a lot of fuzzing with 2.1.x though and we've fixed all the security issues that were reported.
Would I be better off just completely uninstalling VLC Media Player?
AFTER EDIT: I might have considered a direct answer to my question (whatever the answer was) more helpful than a silent downvote to what was, after all, just a polite response to a question that someone asked me.
AFTER FURTHER EDIT: After some more rebooting of the previously infected computer, the operating system and Secunia both report that VLC Media Player version 2.1.3 is installed, and that is not reported to have any problem by Secunia. So I will leave that alone. The computer from which I usually post to HN, a different computer on the same home network, does not have VLC Media Player installed. I try to keep a close-to-bare-stock set of installed programs on this computer, but other users in my household (= teenage boys who aspire to be hackers) tend to install programs I've never heard of on the other computer on our home network, and my wife, who has other things on her mind, occasionally doesn't notice installations of crapware or adware or bloatware that tag along with legitimate program updates on that computer. So that other computer tends to be the vector for malware attacks on the home network here. Thanks for any further comments participants here have on how to keep a home network safe when not all users follow strict quarantine policies.
I would have thought windows could limitate the amplitude of the sound sent to the hardware, maybe VLC is somehow bypassing this.
Seems like an odd issue though.
I once acquired an audio geologic recording of the tragic Christmas Eve tsunami in Indonesia. It was an interesting listen, with a lot of bass/sub-base frequencies. Played at what seemed a reasonable listening volume, it managed to destroy my iPod headphones. Seems some sounds can be inherently damaging to less robust equipment when seemingly operated well within sensible limits.
(The replacement of said headphones cemented my appreciation of Apple: at a time Apple wasn't selling headphones alone, upon my consternation of not being able to buy a set, a clerk ripped open a random box and handed me new headphones gratis.)
(Yes i suppose that is morally wrong, but so is blaming VLC for your own bad designs)
If we had a normal society anywhere on earth they would be sued to the ground there.
But of course, the people that burn their speakers this way don't care about dynamics or evidently about sound quality if they press their computer speakers like this. Can't sound not even a little good.
And they should be built to be able to withstand any valid signal.
On the second, the screen began to go at 14 months. I would never by consumer electronics from Dell again.
Speakers/amps should have DC protection builtin.
Limiters cannot either distinguish or protect against the technical difference between a sine wave and a square wave:
http://i.imgur.com/oE5NFZ9.png
The red trace is a normal audio signal that doesn't exceed the dynamic range of the amplifier. The green trace is an example of the kind of signal one gets by turning the volume up way above normal.
In a hypothetical speaker of one ohm and a peak voltage of one volt, the red trace has a time-averaged power level of 1/2 watt. The green trace has a power level of one watt -- twice as high, and possibly too high for the speakers to tolerate.
> Speakers/amps should have DC protection builtin.
This example should show that this isn't possible without taking the temperature of the speaker's activation coil -- and even that might not work.
That and hard clipping is obvious and sounds awful, so it should be apparent you're doing something wrong.
I've seen it happen many times in meetings. 1. Presenter shows a video and volume is low. 2. Presenter adds volume from VLC to 200% and sound signal gets distorted. 3. Sound is awful, no-one can hear anything and people are doing nothing to fix it, because they think that speakers are broken.
Please VLC, fix your player so that it has good sounding limiter on the "output". It's not difficult.
