[SOLVED] ReplayGain showing incorrect values

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RobNC
Posts: 5
Joined: Tue Sep 22, 2020 4:52 pm

[SOLVED] ReplayGain showing incorrect values

Post by RobNC »

I usually use 3dB lower for ReplayGain. I see that XRECODE shows 75dB to 100dB for ReplayGain. dB shouldn't be from 75 to 100. "dB" is a relative scale.
3dB is double the signal value. 6dB is 4 times. 10dB is 10 times. 20dB is 100 times. 30dB is 1000 times. The equation is as follows:

mutiplicative factor = 10^(dB/10)
100dB implies that the volume would be increased by a factor of 10 billion, which is beyond the range of a 16-bit decode (65535). This would require 37-bit ADC which doesn't exist (as far as I know).

SO, in short, the normalization for ReplayGain should be dB -25 to 0, I think. NOT 75 to 100dB.
admin
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Re: ReplayGain showing incorrect values

Post by admin »

Those values come from mp3gain which used them in this interval.
RobNC
Posts: 5
Joined: Tue Sep 22, 2020 4:52 pm

[SOLVED] Re: ReplayGain showing incorrect values

Post by RobNC »

I see, had some learning to do. Looks like 89dB is the default target for ReplayGain (used by mp3gain):
http://wiki.hydrogenaud.io/index.php?title=Replaygain


"The target loudness of almost all ReplayGain utilities is 89 dB SPL when replayed in an SMPTE RP 200 calibrated system (an early departure from the proposal, endorsed by its author[1]) — the ReplayGain proposal and SMPTE recommendation are 6dB lower.[2]"

Please feel free to close this "bug" as it's not really a bug, it's just the range of inputs to mp3gain.

https://www.mars.org/mailman/public/mad ... 00993.html
https://hydrogenaud.io/index.php/topic, ... #msg721854
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