MP3 Gain Basic Understanding

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DBridgf
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MP3 Gain Basic Understanding

Post by DBridgf »

I am brand new to manipulating sound and new to MediaMonkey (MM). I am trying to understand how to make two songs play back at the same volume level using ID3 Tags not physically altering the file (which I assume is "analyze volume" as opposed to "level track volume" which will alter the physical file). I have several questions and at the bottom of this I have included my assumptions. I would really appreciate any answers to the specific questions I have listed and any comments that would correct misunderstandings in my assumptions. THANKS
QUESTIONS:
1) What specifically are the columns labeled "Track Volume" and "Album Volume". (are they ID3 Tags?)
2) I can not manually change the "Album Volume" numbers. I assume that it is an ID3 Tag which I should be able to manually alter (like I can the "Track Volume"). Why can't I change "Album Volume" or how CAN I change it?
3) Under the heading at the top (File, Edit ... Play) if you put a check mark on LEVEL PLAYBACK VOLUME by pressing PLAY; LEVEL PLAYBACK VOLUME ... does this a) actually alter the file or the ID3 Tags or b) does it only affect how the music plays back based on already established ID3 Tags?
4) I took two test files. Both have an "Album Volume" of -.03. I selected both and did "Analyze volume" which changed "track Volume" for # one to -0.1db and # two to -0.5. Play has a check mark on "level playback volume" and when I play them both they sound the same level. I then manually changed the "track volume" on # one to +10.0 db and # two to -10.0 db and when I playback they also sound the same level .... I don't understand, shouldn't the two sound dramatically different in volume? How can I manually alter the files to hear a dramatic difference so that I can better understand what each ID3 tag does to the file?
5) I took 20 files from various albums. I did an "Analyze volume" and all went to "Album Volume" of -6.9 with "Track Volume" varying around -6.0 (-4.9 to -7.9). Then I took the same 20 files and did a "Level Track Volume". I was expecting the Album Volume and Track Volume to go to 0.0 since the file itself was being set to 89db. Instead the Album volume varied from -2.1 to +.6 and the Track Volume varied from -0.7 to _0.5. After a "Level Track Volume" shouldn't the numbers go to zero. Then I took the 20 files that had been "Level Track Volume" and did an "Analyze volume" ... expected that to also be zero since it was already already hardcoded to 89 .. .but it also had a variance from -2 to +2. Why was it not zero.

This is what I have read (if I have read it correctly):
MP3 digital music also allow Track information to be embedded using “ID3 Tags”. The ID3 Tags have evolved starting with ID3v1 and as they evolved the new Tags began allowing more information to be stored into the newer version Tags. MediaMonkey supports both ID3v1 and ID3v2 (version ID3v2.3 and ID3v2.4).
In order to level the sound from different MP3 songs that playback at different loudness, the songs can be either 1) permanently changed (MP3 Gain) or 2) temporarily changed (Replay Gain).

Replay Gain (achieved by using “Volume Analysis”): With Media Monkey first track volumes are analyzed and the resulting coefficient is saved to the track's tag (Track gain). Then after all tracks on an Album have been analyzed, a single coefficient is saved for all tracks on the album (Album gain). Then, during playback, the Album or Track gain tag is read and the player adjusts the volume up or down accordingly (Album gain is preferable for playing an entire Album and preserving the inter-track volume variances encoded in the original album, while Track gain is preferred for playing a playlist of tracks from various sources). This is an excellent approach for PC-based players, but is limited because many portable devices do not support Replay Gain tags, and thus when tracks are synced to a device, the volume will vary. MediaMonkey supports Replay Gain analysis and playback (per Track and per Album via 'Analyze Volume' and 'Level Playback Volume').

MP3 Gain (achieved by using “Level Track Volume” or “Volume Leveling”): This is a variation on Replay Gain, the difference being that rather than saving the analysis co-efficient to a tag, the volume of the MP3 file is actually modified based on the analysis. The benefits of this approach are that like Replay Gain there is no loss in Audio Fidelity, and the resulting MP3 files can be played at level volumes on any MP3 player. The downside is that the approach is limited to MP3. MediaMonkey supports MP3 Gain type volume leveling via the 'Level Volume' command, and can even do so on-the-fly when synching to a device.
nohitter151
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Re: MP3 Gain Basic Understanding

Post by nohitter151 »

1. Depends on file type but yes. See http://www.mediamonkey.com/wiki/index.p ... erties/4.0

2. No album volume cannot be altered manually

3. It does not affect tagging at all, it simply enables/disables tracks playing back with equalized volume

4. Probably because you have "Clipping prevention" enabled. See Options > Volume leveling. Something with a huge value like +10.0db is sure to cause clipping in the file so it will not actually use this value.

5. The algorithms used are quite complicated and so it doesn't work as simply as this.
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DBridgf
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Re: MP3 Gain Basic Understanding

Post by DBridgf »

THANK YOU THANK YOU. Very clear and concise. I am starting to understand. A couple of more questions please:
1) DONE. File type is MP3 ... got it, yes, THANKS.
2) You may say "it just is that way" ... but curious why an MP3 Tag such as "album volume" (which seems so critical to volume) would not be changeable. I thought all Tags were changeable. Is there a reason or is it "just is"?
3) DONE. Got it, THANKS
4) I still can not manually cause a wide variance in sound volume ...doing so will help me understand what these Tags do. Not being able to do it confuses me. I checked "Clipping prevention" and it WAS turned on, I turned it off and still did not make any difference. I also tried it with "Level Playback Volume" under "PLAY" turned on and off and no difference. Again I made Song #1 +10dB and Song #2 -10dB and could hear no difference (also tried +5 -5 still no change). I must point out that I am not knowingly saving these changes ... I don't see how, I am assuming that it is dynamically saving. I shut MM down then restart it and the setting are all the same as when I set down (so again, I assume that it is saved dynamically). Any suggestions on how to demonstrate a wide sound variance manually?
5) DONE. Understood .. THANKS.
6) How DO you save changes that you make to file Tags?

PS, I am using Windows 7 Ultimate.
Lowlander
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Re: MP3 Gain Basic Understanding

Post by Lowlander »

6) This is done by default (Tools > Options > Tags & Playlists, Update tags when editing properties) and can be done manually with Tools > Advanced Tag Management > Synchronize Tags.
Lowlander (MediaMonkey user since 2003)
emalvick
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Re: MP3 Gain Basic Understanding

Post by emalvick »

Some of your answers are just the way it is in Media Monkey. You could edit the tags in a different software like MP3Tag.

In terms of playing tracks with different gain tags and then changing them, you do have to keep in mind whether you are playing tracks from the same album or different albums. If you are playing tracks from the same album, then changing the Track Gain might not do anything since the player may in fact be using Album Gain.

MM may try to avoid clipping as was suggested earlier.

As for using the leveling command, I know that the adjustment is a fixed value, so I wouldn't expect both Gain fields to go to zero. Afterall, it is rare that the Album Gain = Track Gain and the leveling adjustment is a constant. I believe that the software attempts to level by the Track Volume, but I also believe that it does so by adjusting by fixed increments in track value. I'm not sure what that increment is, it may be integers of decibels or something similar such that if the Track Gain was -4.3, MM may only do the leveling by -4 and the Track Gain tag would then be -0.3 to represent the remaining adjustment that wasn't hard coded. I know that this is the way Winamp used to do it, and I think MM at one point used something similar and perhaps still does.
nohitter151
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Re: MP3 Gain Basic Understanding

Post by nohitter151 »

2. It just is in MediaMonkey. Not sure of the reason, maybe because you might expect changing the value for one track should update the entire album, but that functionality doesn't exist or might be confusing for some users. Hard to say. Some other tag editors could change it I'm sure

4. If I disable clipping prevention it's obvious on my system... not sure
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DBridgf
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Re: MP3 Gain Basic Understanding

Post by DBridgf »

Thanks ... I am starting to get it, slowly but surely. :D. Now I will play with it ...
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