IPB

Welcome Guest ( Log In | Register )

 
Reply to this topicStart new topic
Does iTunes have peak protection? And QuickTime?
Jplus
post Feb 14 2013, 13:54
Post #1





Group: Members
Posts: 41
Joined: 7-February 13
Member No.: 106471



Something I was just wondering about... I learnt to never put the volume to the maximum, because the signal may be capped which sounds bad and may potentially damage your speakers. However, I discovered that VLC has a setting that says "enable peak protection", meaning that you can safely put the volume to 100% without fear of capping.

Now that I know about it it makes a lot of sense to me that a decent audio player would offer such a feature. That makes me think that iTunes and QuickTime probably do it too, but without telling the user about it. Could anyone confirm that? Sofar I've been unable to find any conclusive answer on the internet. If I knew for sure that I can safely max out the volume in iTunes I'd find that very convenient.

As an aside, is there any disadvantage to peak protection?
Go to the top of the page
+Quote Post
frozenspeed
post Feb 14 2013, 16:40
Post #2





Group: Members
Posts: 207
Joined: 16-October 01
From: Seattle, WA
Member No.: 301



QUOTE (Jplus @ Feb 14 2013, 05:54) *
Something I was just wondering about... I learnt to never put the volume to the maximum, because the signal may be capped which sounds bad and may potentially damage your speakers. However, I discovered that VLC has a setting that says "enable peak protection", meaning that you can safely put the volume to 100% without fear of capping.

Now that I know about it it makes a lot of sense to me that a decent audio player would offer such a feature. That makes me think that iTunes and QuickTime probably do it too, but without telling the user about it. Could anyone confirm that? Sofar I've been unable to find any conclusive answer on the internet. If I knew for sure that I can safely max out the volume in iTunes I'd find that very convenient.

As an aside, is there any disadvantage to peak protection?



I don't think either do but the iPod provides Apple's version of RG called SoundCheck or something like that.
Go to the top of the page
+Quote Post
mixminus1
post Feb 14 2013, 17:21
Post #3





Group: Members
Posts: 688
Joined: 23-February 05
Member No.: 20097



iTunes/QuickTime don't have "peak protection" because they don't allow you to add gain to a digital signal: at full volume in either iTunes or QuickTime, 0 dBFS from a PCM audio file = 0 dBFS out to the audio driver.

VLC, for some bizarre reason, does allow you to add substantial gain, and thus can easily drive a signal well into digital clipping. Its "peak protection" is basically a real-time normalizer that decreases gain anytime it detects clipping.

As an aside, the DirectShow AC3Filter has had that same feature for quite some time, which works in tandem with its dynamic range compression (DRC).


--------------------
"Not sure what the question is, but the answer is probably no."
Go to the top of the page
+Quote Post
DVDdoug
post Feb 14 2013, 20:28
Post #4





Group: Members
Posts: 2610
Joined: 24-August 07
From: Silicon Valley
Member No.: 46454



If you are not "processing" the signal (boosting the bass with a software equalizer or a software "preamp", etc.) most applications won't clip, because at full volume, they are basically sending the unaltered raw audio data to the DAC. So the signal coming out of your soundcard or iPod is probably clean, even at full volume.

If you have a headphone amplifier, or a power amplifier driving speakers, you can clip (distort) the amp.

QUOTE
...because the signal may be capped which sounds bad and may potentially damage your speakers.
That would depend more on the power rating of your power amp and the power rating of the speakers. Speaker power ratings are confusing (and sometimes they are just made-up), but a 100W speaker is supposed to work with a 100W amp playing undistorted music... You can probably blow the tweeter in a 100W speaker with a 20W test-tone.

JBL recommends a power amp with twice the speaker rating with normal undistorted music or voice. For electric guitar or other applications there there is commonly distortion, they recommend the opposite... A speaker with twice the power rating of the amp. But, that's related to average power more than clipping... A 100W amp that's constantly clipping is putting-out more average power (and generating more heat in the speaker voice coil) than a 100W amp that's never clipping (or occasionally cipping).

But, the idea that clipping will burn-out your tweeter is mostlya myth. You are more likely to fry you tweeter with a high-power amp playing at full volume than with a low-power amp pushed into severe clipping.

With headphones, you are more likely to damage your ears than the headphones.

This post has been edited by DVDdoug: Feb 14 2013, 20:32
Go to the top of the page
+Quote Post
Jplus
post Feb 15 2013, 17:57
Post #5





Group: Members
Posts: 41
Joined: 7-February 13
Member No.: 106471



Thanks folks.

So I guess that means 1) that peak protection isn't doing anything useful for me in VLC because I don't add gain beyond 100% and 2) I can safely put the volume to 100% in iTunes and QuickTime.

Still one question. I have 2.1 speakers connected to my computer by minijack. The cable is routed through the subwoofer box before it splits to the tweeters, and since the set is able to produce a lot of volume I presume some power amplification is done in the subwoofer box. It's sold as a set so I assume the power rating of the speakers is tuned to the power rating of the amp. I usually put the volume of the speakers much lower than it can go so for with music with little or no distortion it should be safe. But what about less reliable sources of music such as YouTube?

As for the headphones, I'm always very careful with those. smile.gif
Go to the top of the page
+Quote Post

Reply to this topicStart new topic
1 User(s) are reading this topic (1 Guests and 0 Anonymous Users)
0 Members:

 



RSS Lo-Fi Version Time is now: 1st October 2014 - 14:41