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Are my assumptions of MP3Gain correct?
Nazgulled
post Apr 6 2012, 01:45
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Hi,

I've been using MP3Gain for some years now but up until recently I discovered something I was not aware and it's confusing me a little bit. I'm wondering if I have been using MP3Gain the way I thought I wanted... Sorry if this has been discussed before but I searched a lot (on these forums and Google) and couldn't find anything related.

I use MP3Gain so that when play my mp3s on my favorite media payer, they are normalized and play, roughly, with the same volume. I use Songbird and this media player has an option to "use audio normalization data" (with the options for track/album, I use track). To better explain things, I'll use an example...

I have this mp3 file, which, after analysis, reports a volume of 96.2.

When I set the target volume to 105 (just for example purposes), the mp3 final volume is 105.3 and the it contains this:
QUOTE
REPLAYGAIN_TRACK_GAIN=-16.26000 dB

When I set the target volume to 75 (just for example purposes), the mp3 final volume is 75.2 and the it contains this:
QUOTE
REPLAYGAIN_TRACK_GAIN=+13.84000 dB

If we do some basic math, we get this:
QUOTE
105.3 - 16.26 = 89.04 ~ 89.0
75.2 + 13.84 = 89.04 ~ 89.0

And the fact is, when I play this file with either target volume applied on Songbird with the normalization option enabled, I get the same volume level. If I disable the normalization option, I get different volume levels. The first one much louder than the latter, of course.

So, with my findings above, I conclude the following:
  • The target volume will have zero impact on media players which support reading of audio normalization data (generated from MP3Gain at least, I believe this is called ReplayGain). However, the target volume will have impact on media players which don't support reading of audio normalization data (or if such option is disabled). For instance, Windows Media Player. This player will play the 105 file above louder than the 75 one.
  • MP3Gain will always default to 89.0dB to set the replaygain track gain tag (which applications like Songbird read from) and there seems to be no way to change this.

Q1)
Are my assumptions of MP3Gain correct? I guess so because this is what I observed happening...

Q2)
What I want from MP3Gain are 2 things, a) normalize all mp3 to the same volume, b) increase that same volume a little bit.

Since MP3Gain always defaults to 89.0dB and there's no way to change it (or is there?) and since I want to have all my mp3s volume higher than 89.0dB, I guess my only option is to normalize all my mp3s with MP3Gain setting the target volume to my liking and don't enable the normalization option in Songbird. Right?

My real question here is, will all my mp3s still be normalized to that same target volume?

I would really appreciate some insight on this matter from the gurus out there... Thank you for your time.

This post has been edited by Nazgulled: Apr 6 2012, 01:47
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2Bdecided
post Apr 6 2012, 14:28
Post #2


ReplayGain developer


Group: Developer
Posts: 5057
Joined: 5-November 01
From: Yorkshire, UK
Member No.: 409



QUOTE (Nazgulled @ Apr 6 2012, 01:45) *
Since MP3Gain always defaults to 89.0dB and there's no way to change it (or is there?) and since I want to have all my mp3s volume higher than 89.0dB, I guess my only option is to normalize all my mp3s with MP3Gain setting the target volume to my liking and don't enable the normalization option in Songbird. Right?
Yes, unless Songbird includes a "pre-amp" setting to add the increase there.

QUOTE
My real question here is, will all my mp3s still be normalized to that same target volume?
The same target value as each other? Yes, if you always set the same target value in mp3gain.


I think most people either
a) get mp3gain to change the mp3s, and then let dumb software play those mp3s as-is, or
b) get something to write ReplayGain tags to their mp3s, and then let smart software read those tags and apple the gain change

I think it's quite rare for people to do both - i.e. change the audio data, and read the tags.

(Unless they apply the album gain using mp3gain, and listen to those mp3s on any dumb player - but then use the track gain tags in some smart player. Or maybe have a louder target value applied to their mp3s for portable listening, but then read the tags to get a lower non-clipping value for at-home listening on a smart player. Or some other specific use.)

Cheers,
David.
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