Old 28th June 2011, 18:01   #1
Neutrino Sunset
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Volume correction - gain vs playback volume

In my media library I have some tracks which are loud and some which are quiet and I've been reading up on the various ways to remedy this so I don't have to keep changing the playback volume level.

However, the more I read about this the more confused I get.

I've read that I can use a program like Mp3Gain to adjust the gain values in the mp3 files and that there are two ways of doing this.

One way modifies the 'global' gain fields of the mp3 data frames. Confusingly this modifies the volume in the actual data stream and is not a global setting. When this is done the program making the modification can add a value into the file's metadata header so that the change can be losslessly reversed.

The second way is to add a value into an mp3 file's metadata which instructs a Replay Gain aware player to apply a 'global' (this time as in file level) gain modification to the entire data stream.

From what I've read though it seems that a limitation of this approach is that an mp3 signal has a limited range of gain which it can represent before clipping of the signal occurs, and that this must be avoided because it will degrade the playack quality.

I have quite a few old tracks that are analog recordings which sound much quieter than most of the more modern music rips I have. Despite this the old tracks are already at the gain clipping limit. I've read that this discrepency is due to most modern stuff being heavily compressed and thus can sound much louder before clipping would occur.

So I think that means I can't use this method to increase the gain of these older tracks to normalise the volume of my library without destroying their quality through clipping, and indeed wouldn't want to because as these tracks are already normalised such that their peak signal is just below the mp3 clipping threashold they are already perfectly formatted.

All I want to do is tag them to play at a relatively louder output volume, and it seems to me that output volume is a function of amplification which can take place after any digital to analog conversion, so I don't see why I shouldn't be able to do this without adjusting the mp3 gain levels at all.

I think I'm clearly not understanding this properly and could do with some guidance. Please feel free to talk to me like I'm an idiot, it's the only way I'll learn
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Old 28th June 2011, 18:12   #2
MrSinatra
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forget mp3gain. it actually applies gain to the audio itself. undesirable, and useful only in limited and specific circumstances.

ReplayGain (or similar) is the only sensible thing to use. it adds text values as tags to the file. then in the winamp app, you tell it how to use the tags. the gain is applied at playback, but the actual audio is not touched.

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Old 28th June 2011, 18:34   #3
Neutrino Sunset
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I got the impression that there is a defacto standard/protocol called 'Replay Gain'. That this standard has two means of adjusting the mp3 gain, namely using the global gain fields of the data stream and a (genuinely) global file metadata gain tag.

But I thought that Mp3Gain and the Winamp ReplayGain plugin were both implementations of this same standard and that the issue regarding signal clipping applied to them both in the same way.

Is this not the case? If I add a file level gain tag will Winamp apply that as a volume correction in a manner that will not cause clipping then? If so that sounds like the solution I'm looking for.

P.S. Looking at the links in your sig MrSinatra hasn't the issue with column sorting been fixed? I think I have Media Library setup the same as you, Album Artist on the left, Album Art on the right, tracks below, and in my Album Art pane I can sort albums by year or by anything else. (using Winamp 5.61).
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Old 28th June 2011, 19:13   #4
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Quote:
Originally Posted by Neutrino Sunset View Post
I got the impression that there is a defacto standard/protocol called 'Replay Gain'. That this standard has two means of adjusting the mp3 gain, namely using the global gain fields of the data stream and a (genuinely) global file metadata gain tag.
i don't follow you. RG uses tags in the file, metadata. the app then adjusts the gain based on those text values.

Quote:
Originally Posted by Neutrino Sunset View Post
But I thought that Mp3Gain and the Winamp ReplayGain plugin were both implementations of this same standard and that the issue regarding signal clipping applied to them both in the same way.
afaik, no. as i said, mp3gain adjusts the actual audio, RG does not.

i have only had "prevent clipping" affect one file, that prob has a bad spike in it. you don't have to use prevent clipping anyway.

Quote:
Originally Posted by Neutrino Sunset View Post
Is this not the case? If I add a file level gain tag will Winamp apply that as a volume correction in a manner that will not cause clipping then? If so that sounds like the solution I'm looking for.
look in winamp prefs at RG and choose the RG u want to implement on playback.

Quote:
Originally Posted by Neutrino Sunset View Post
P.S. Looking at the links in your sig MrSinatra hasn't the issue with column sorting been fixed? I think I have Media Library setup the same as you, Album Artist on the left, Album Art on the right, tracks below, and in my Album Art pane I can sort albums by year or by anything else. (using Winamp 5.61).
thats not the issue. the issue is in picking more than one column to sort by.

for example, in the view we use, the albums [art] are all arranged alphabetically under each album artist, right? ok, good if you want that... but what if i want them arranged by year under each albumartist? you can't do that from the big list, you would have to pick an individual AA first.

thats just one example, multiple column sorting has endless variations like that.

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Old 29th June 2011, 13:15   #5
Neutrino Sunset
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Replay Gain is a standard volume normalization scheme.

Mp3Gain and Winamp ReplayGain plugin are both just tools which utilise that standard. So it seems to me they both do exactly the same thing so I don't understand why you say that Mp3Gain would cause clipping but Winamp ReplayGain would not.

Mp3Gain applies the volume adjustment to the mp3 frame fields (i.e in the data stream itself), whereas Winamp ReplayGain tags the file in metadata with the amount by which to adjust the gain, but the actual adjustment and it's ultimate effect is the same in both cases, it's just a difference in how the modification is stored.

Because Mp3Gain modifies the data stream that adjustment is transparently picked up by all playback software (whether they understand Replay Gain or not), whereas the adjustment made by the Winamp ReplayGain plugin would only be picked up by software which understands the Replay Gain standard.

But unless I've misunderstood something the application of that gain by the media player software should have exactly the same effect shouldn't it?

I'll test it and see what happens.
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Old 29th June 2011, 19:27   #6
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Quote:
Originally Posted by Neutrino Sunset View Post
Replay Gain is a standard volume normalization scheme.

Mp3Gain and Winamp ReplayGain plugin are both just tools which utilise that standard. So it seems to me they both do exactly the same thing
incorrect, but u can believe what you want.

i'll say it one last time. mp3gain applies the gain to the FILE/AUDIO itself, while RG applies it via the APP on playback, via tags.

Quote:
Originally Posted by Neutrino Sunset View Post
so I don't understand why you say that Mp3Gain would cause clipping but Winamp ReplayGain would not.
i didn't say that. normally, neither should cause clipping altho i don't use mp3gain so i have no exp with it. but if using RG and winamp, you can on playback just apply gain, or apply gain AND prevent clipping. its up to you.

Quote:
Originally Posted by Neutrino Sunset View Post
Mp3Gain applies the volume adjustment to the mp3 frame fields (i.e in the data stream itself),
exactly. it adjusts the audio directly. i would never do that.

Quote:
Originally Posted by Neutrino Sunset View Post
whereas Winamp ReplayGain tags the file in metadata with the amount by which to adjust the gain,
exactly what i said. it also tags a "peak" value which is how it prevents clipping.

Quote:
Originally Posted by Neutrino Sunset View Post
but the actual adjustment and it's ultimate effect is the same in both cases, it's just a difference in how the modification is stored.
in theory this is true, but you can't turn it "off" when applied to the data as opposed to the tags, and i would never adjust the data in this way.

also, i don't know, but would guess, that mp3gain doesn't do anything regarding peak values.

Quote:
Originally Posted by Neutrino Sunset View Post
Because Mp3Gain modifies the data stream that adjustment is transparently picked up by all playback software (whether they understand Replay Gain or not), whereas the adjustment made by the Winamp ReplayGain plugin would only be picked up by software which understands the Replay Gain standard.
true, but anything decent does, and i wouldn't use anything that doesn't. this is what i was referring to when i said above that mp3gain can be useful in limited circumstances.

Quote:
Originally Posted by Neutrino Sunset View Post
But unless I've misunderstood something the application of that gain by the media player software should have exactly the same effect shouldn't it?

I'll test it and see what happens.
well, as i said, the peak info/clipping info might be missing from mp3gain altogether, and i would not apply gain to my files, not just b/c of the theory of it, but b/c i think mp3gain stores undo info in ape tags, and i don't want that either. and what if you lose the tags, you can't undo the gain then.

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Old 29th June 2011, 23:26   #7
Neutrino Sunset
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Replay Gain (the standard) includes a standard mechanism for determining the percieved loudness of a track, so I think that means that Mp3Gain and Winamp ReplayGain will both treat peak values similarly.

After more research I think I've concluded that Winamp ReplayGain will indeed suit my purpose, but not quite for the reason you think it will

I'm still pretty convinced that functionally Mp3Gain and Winamp ReplayGain have the same effect, although achieved in slightly different ways, though I agree with your valid concerns about modifying the data stream directly and losing the undo tags.

What's different about Winamp ReplayGain though isn't that it has a functionally different effect on the tracks it gains, but that it has an additional effect on the tracks it _doesn't_ gain. Because with Winamp ReplayGain you can configure it to reduce the volume of anything that hasn't been ReplayGained.

This is how you can make a quiet track play louder using Winamp ReplayGain even if you can't gain the quiet track any further without clipping it. You just run Replay Gain on the quiet track but don't increase the gain to a point that would cause clipping, and then configure the Winamp ReplayGain behaviour to make everything else much quieter.

I haven't had a chance to test it yet as I've been crazy busy today, but I'm optimistic it will work.
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