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"MP3Gain: How can it be possible?", It 's indicated that the gain adjustments are lossless
Typhoon859
post Aug 1 2012, 00:35
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So I've been thinking of trying to write a similar program from scratch and there's one main thing that I don't even understand how it's possible, yet alone done. So as is said, the process MP3Gain uses is lossless. Thinking about it, the only way MP3Gain could work where any player would play back the songs with whatever the target volume was would be if the change is present in the waveform. After MP3Gain is applied, if it weren't obvious from the beginning, in any audio editing software, the gain reduction is clearly visible. I could somewhat understand how the process can be reversed with added value, even if the waveform clips, as the information could still somehow be stored (more easily than the other way around). On the other hand, when taken away, don't you permanently lose the dB that you took from the threshold? As an example, if a song starts with some 6 decibel ambient noise and you reduce the song by 6dB, wouldn't that intro just completely disappear? And if the change is undone, wouldn't you not get any of the data back (unless it's stored) and just make the existing data 6dB louder? If that's the case, it isn't really undoing the changes; it's really just adding the difference in value back between the indicated ReplayGain value and what it is now.

Sorry this was kinda long-winded but the last thing though I'd also like to ask about is clipping. If a track's peak values are clipping by default, reducing the loudness now would be too late, wouldn't it? Wouldn't it be clipping no matter what at this point, contrary to what is indicated? The peaks would be chopped off either way since the structure of the waveform is no longer saved after being finalized. And also, the maximized volume indications don't make sense (has to be turned on in the options). For example, I have a file which ReplayGain indicates peaks at about 1.05 (16-bit = 100.8dB) and yet it's marked that only a 1.5dB reduction would be necessary to get it maximized (the loudest point before clipping - 96dB). Is there something I'm missing?

Thanks guys! Answers to these would be extremely helpful.


PS- A lot of the things here indicate to me that the values, whether over or under, remain as part of the data in the container but just doesn't play back, or rather, clips since it's within the 16-bit parameter.
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2Bdecided
post Aug 3 2012, 09:58
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ReplayGain developer


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I think we scared him off.

Interesting how, on a generally friendly board, a conversation can go so wrong.
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skamp
post Aug 3 2012, 10:11
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QUOTE (2Bdecided @ Aug 3 2012, 10:58) *
Interesting how, on a generally friendly board, a conversation can go so wrong.


There's actually often friction with newbies here. Get off my lawn type of reactions.


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Posts in this topic
- Typhoon859   "MP3Gain: How can it be possible?"   Aug 1 2012, 00:35
- - greynol   You appear to assume that mp3 data is 16-bit integ...   Aug 1 2012, 00:50
|- - 2Bdecided   QUOTE (greynol @ Aug 1 2012, 00:50) I rec...   Aug 1 2012, 13:59
- - saratoga   QUOTE (Typhoon859 @ Jul 31 2012, 19:35) I...   Aug 1 2012, 02:25
|- - greynol   Since we're not dealing with power, a ~0.2dB i...   Aug 1 2012, 03:30
|- - saratoga   QUOTE (greynol @ Jul 31 2012, 22:30) Sinc...   Aug 1 2012, 15:01
- - Typhoon859   Right, so, there evidently seems to be a lot I don...   Aug 1 2012, 13:24
|- - db1989   QUOTE (Typhoon859 @ Aug 1 2012, 13:24) In...   Aug 1 2012, 14:24
|- - saratoga   QUOTE (Typhoon859 @ Aug 1 2012, 08:24) Re...   Aug 1 2012, 16:06
- - pdq   I seem to recall that the dynamic range of the mp3...   Aug 1 2012, 14:16
- - mjb2006   QUOTE (Typhoon859 @ Jul 31 2012, 17:35) i...   Aug 1 2012, 19:31
- - Typhoon859   First of all, I'd just like to say that many o...   Aug 2 2012, 06:40
|- - saratoga   QUOTE (Typhoon859 @ Aug 2 2012, 01:40) QU...   Aug 2 2012, 16:05
- - Typhoon859   QUOTE (mjb2006 @ Aug 1 2012, 14:31) If yo...   Aug 2 2012, 06:45
|- - 2Bdecided   QUOTE (Typhoon859 @ Aug 2 2012, 06:45) Wh...   Aug 2 2012, 11:53
- - halb27   A short explanation of mp3 technology in the entir...   Aug 2 2012, 10:20
- - db1989   QUOTE (Typhoon859 @ Aug 2 2012, 06:40) QU...   Aug 2 2012, 11:05
- - [JAZ]   @Typhoon859: You should read again your posts, and...   Aug 2 2012, 13:03
|- - [JAZ]   QUOTE ([JAZ] @ Aug 2 2012, 14:03)...   Aug 2 2012, 17:38
|- - alanofoz   QUOTE ([JAZ] @ Aug 3 2012, 03:38)...   Aug 3 2012, 02:52
- - greynol   You're saying full scale is not maximum amplit...   Aug 3 2012, 04:51
|- - alanofoz   QUOTE (greynol @ Aug 3 2012, 14:51) You...   Aug 3 2012, 23:50
|- - [JAZ]   QUOTE (alanofoz @ Aug 4 2012, 00:50) QUOT...   Aug 4 2012, 10:55
- - [JAZ]   The signal to noise ratio is the difference betwee...   Aug 3 2012, 09:54
- - 2Bdecided   I think we scared him off. Interesting how, on a ...   Aug 3 2012, 09:58
|- - skamp   QUOTE (2Bdecided @ Aug 3 2012, 10:58) Int...   Aug 3 2012, 10:11
|- - 2Bdecided   QUOTE (skamp @ Aug 3 2012, 10:11) QUOTE (...   Aug 3 2012, 10:51
|- - Destroid   QUOTE (2Bdecided @ Aug 3 2012, 10:51) Ser...   Aug 3 2012, 11:17
|- - bandpass   QUOTE (2Bdecided @ Aug 3 2012, 10:51) The...   Aug 3 2012, 11:31
- - Destroid   Actually, I hope this person is still lurking and ...   Aug 3 2012, 10:50
- - greynol   Allow me to throw another reason into the mix as t...   Aug 3 2012, 15:36
- - alanofoz   Hmmm... I re-read my post and didn't think it ...   Aug 5 2012, 01:53


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