use of dB unit without suffix in Normalization preferences is confusing

[mixxxbot]

Reported by: Be-ing
Date: 2016-03-23T17:41:49Z
Status: New
Importance: Undecided
Launchpad Issue: lp1561131

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Under the "Target loudness" slider in the normalization preferences, the position of the slider is noted in terms of LUFS, with "(adjust by X dB)" after the LUFS. It seems that the dB measurement is in reference to -18 LUFS, but for a long time I have been confused in thinking that it was in reference to digital full scale and that ReplayGain would adjust my tracks by that many dB relative to how they are recorded. I did not understand that ReplayGain was making my tracks substantially quieter until I played with toggling ReplayGain on and off and realized I had to put the Target loudness slider to +6 dB (-12 LUFS) for tracks to reach the same levels on the level meters without ReplayGain applied. The use of "dB" in this unusual way is confusing. I'm not certain what the best way to make this less confusing would be. Perhaps simply removing the "(adjust by X dB)" text would help to make it clear that the Target loudness slider is only dealing with LUFS, not dBFS.

[mixxxbot]

Commented by: Be-ing
Date: 2016-03-23T18:53:06Z

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The pending ReplayGain 2.0 PR solves the issue with having to turn the slider up to -12 LUFS, but the confusing use of "dB" remains.

[mixxxbot]

Commented by: daschuer
Date: 2016-03-23T20:14:11Z

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It seems that the dB measurement is in reference to -18 LUFS

That is correct. -18 LUFS is the ReplayGain reference loudness.

We have added the dB value witch is basically an additional gain to the normalized -18 LUFS track.

In the 1.11 version, we had only the dB value. And it helps to compare the LUFS slider with the Initial Boost slider below and the
Replay Gain value in the library column.

A dB scale is the most common scale for gain and volume slider, and it should catch the user who are not familiar with LUFS. It has nothing to do with dBFS, which is a unit for peak sample measurement.

[mixxxbot]

Commented by: Be-ing
Date: 2016-03-23T20:33:39Z

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I don't know of anything else that uses dB in reference to -18 LUFS, so I doubt I'm the only one who got confused and thought that the dB value is in reference to a more common reference for dB, such as 0 dBFS. I think removing the "(adjust by X dB)" and only show LUFS would be clearer.

[mixxxbot]

Commented by: daschuer
Date: 2016-03-23T20:44:33Z

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OK, I can live without ;-)

[mixxxbot]

Commented by: JosepMaJAZ
Date: 2016-04-10T16:39:47Z

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@be: As noted, dB is a relative unit, which expresses the amount of change respect another value. As such 0dBFS expresses the amount of change, versus a predefined level named "Full Scale" (Max digital level, or unity level). This unit only has sense in a meter, not in a fader.

In this case, the slider for the replaygain is indicating a change of gain versus the default target loudness, and usually people require increasing the gain ( i.e. push it nearer to 0 ). Just remember that the usual precautions about mixing gains should be respected.

There is no standarized unit to describe this. It could have been named 0dBRgT ( Replaygain target).
As Daniel says, what has been done to 1.12/2.0 is to express this gain in a more reasonably unit (at least in recent years) which is using the LUFS unit. The expression in dBs helps to know where the 0 point is and should imply the meaning that it is a gain change.

[mixxxbot]

Commented by: daschuer
Date: 2020-05-08T21:04:55Z

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No one has confirmed that bug, close as won't fix?