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About ReplayGain standard
greynol
post Apr 13 2009, 07:21
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QUOTE (waaateva @ Apr 12 2009, 20:32) *
You must not have used MP3Gain. If, for example, you use 89dB as the reference, and it returns a -5dB gain, then you change to 92dB, it'll return -2dB!
So what? The RG value still gets adjusted according to the -89dB reference*. If you load one of my mp3s and change the target volume to something different it will adjust accordingly. Undo will bring it back to exactly where it started as well. Besides, there's nothing stopping me from rescanning. Furthermore, you will never see my mp3s in you collection. I get the feeling that this would never be of any concern to people who encode their own music.

QUOTE (waaateva @ Apr 12 2009, 20:32) *
The real problem is: scanners (and users) are not supposed to change the reference level when scanning, because it is in the standard.
Nonsense.

(*) EDIT: Just to clarify, although MP3Gain allows you to adjust the 'Target "Normal" volume' the Reference level is still 89dB. Notice that it's called "Target Volume" and not "Reference Level".

This post has been edited by greynol: Apr 13 2009, 07:35


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greynol
post Apr 13 2009, 07:24
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QUOTE (waaateva @ Apr 12 2009, 20:32) *
So, because users have the ability (and reasons) to change the reference level, why don't we just remove it from the standard, and store the SPL instead?

Because it's already well supported and works just fine the way it is.


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David Nordin
post Apr 13 2009, 08:33
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QUOTE (waaateva @ Apr 13 2009, 05:08) *
Actually, that's the problem! If you mix your library with mine, who use 89dB, they'll play with different loudness. And there's no way to tell which files scanned with which reference. If, however, RG store the LEVEL instead, you can play with your 92dB "Preferred Level", and I can play with my 89dB. No matter what one chooses, all files in this world, scanned with RG, will have the same loudness. That's what I call standard. Doesn't that make sense?


Now, this is exactly how it works today - what are you missing?
Standard is 89dB, user adjusts with preamp in his player of choice - everybody gets a banana!


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[JAZ]
post Apr 13 2009, 10:33
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I also believe waaateva got confused.

I've checked it to be sure, and indeed, if you aply mp3gain with different target volume, the replaygain values change accordingly.

One has to remember that mp3gain changes the volume of the mp3 data, so the change of the replaygain values is a consequence of that, not of the change of the target volume.

(If i wasn't clear, a file mp3gained at both, 92db and 89db played back in foobar2000 at the same loudness. Of course, a non replaygain aware player would play them at different volumes, but that's out of the scope of the current topic)

This post has been edited by [JAZ]: Apr 13 2009, 10:35
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waaateva
post Apr 13 2009, 10:57
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Guys,
You were right, I was wrong about MP3Gain and MediaMonkey, my bad for not confirming it before posting.
Sorry for the confusion I've made so far, I'll edit my posts.
@greynol, JAZ: thanks for clearing that up for me

Now one more question. Anyone know why the reference level was changed from 83dB to 89dB? Is there any possibility it will be changed again?

This post has been edited by waaateva: Apr 13 2009, 11:09
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Lear
post Apr 13 2009, 13:25
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QUOTE (waaateva @ Apr 13 2009, 10:57) *
Now one more question. Anyone know why the reference level was changed from 83dB to 89dB? Is there any possibility it will be changed again?


Because that's what people actually used (see here). As I recall it, 89 dB was used because 83 dB was seen as a bit low, especially for portable players. Considering it has stayed the same for over 5 years, I wouldn't expect it to be changed again.

As for using level rather than gain, it has been discussed before (both in the thread linked above, as well as here), and was considered too late to change in 2003... smile.gif
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waaateva
post Apr 13 2009, 15:12
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Thanks for the links, they are very helpful. This require a lot more background knowledge than I thought!
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tot
post Apr 13 2009, 15:28
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QUOTE (Lear @ Apr 13 2009, 14:25) *
Because that's what people actually used (see here). As I recall it, 89 dB was used because 83 dB was seen as a bit low, especially for portable players. Considering it has stayed the same for over 5 years, I wouldn't expect it to be changed again.

As for using level rather than gain, it has been discussed before (both in the thread linked above, as well as here), and was considered too late to change in 2003... smile.gif


Reading those old threads and how casually the reference level was changed would suggest that just the reference level number, which is not used in the RG calculation at all, was changed. I wonder why people are so obsessed with the number in the first place...

The only relevance of the reference level is the filter selection to get better match in the perceived loudness, and I doubt it was adjusted at the time. Not that it would make any difference, I am just being pedantic here.


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2Bdecided
post Sep 3 2010, 10:41
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I didn't see this thread at the time, and I certainly don't want to resurrect it because IMO the ideas in it are not good.

However, a Google search now throws it up, so I feel I should add a comment.

The threads linked above include quite long discussions, but the conclusion is here...

http://www.hydrogenaudio.org/forums/index....st&p=170957
QUOTE (2Bdecided @ Jan 8 2004, 13:18) *
When it stored the absolute loudness of the file (e.g. 92dB), it was called Replay Level.

When it changed to storing the relative gain (e.g. -3dB), it was renamed to Replay Gain: relative gains, referenced to making the loudness 83dB through a calibrated system, plus 6dB.

... conceptually, saying the file sounds x dB loud at reference playback level doesn't actually tell you how much to change the gain if the non-parallel equal loudness curves are ever taken into account ... Whereas saying "shift it x dB to make it the reference playback loudness" can include that factor in the calculation.
So it's better the way it is wink.gif

btw, a replaygain_reference_level tag is a very bad idea, because it completely breaks compatibility with all other implementations, and is totally unnecessary. I hope no one has implemented it.

(though I know that data can be implicitly present as part of the undo data when ReplayGain changes have been applied, e.g. by mp3gain, which is fine).

Cheers,
David.
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