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## Replaygain, adulterating the signal or not?

##### 2024-01-07 13:28:21
"so when you turn the volume up or down, you're adulterating the signal? I'd like to see you provide evidence of this effect ..."

Let's focus on the digital side, inside foobar.

1. Assume a music track sample -- original signal sample value is +0.5 FS (full scale).
2. Assume the replaygain is -1dB -- which equates to 0.891.; and preamp gain is 0dB which equates to 1.
3. Foobar will calculate the -- output signal sample value is +0.5FS * 0.891 * 1 = +0.4455FS.
4. Foobar will output the "adulterated" sample value of +0.4455FS to the DAC.
5. This is repeated for every sample in the music track.

We can see that original sample of +0.5FS has now been changed to +0.4455FS.
The sample sent to the DAC is not the same as the original sample from the music file, the signal has been "adulterated".

Quis custodiet ipsos custodes?  ;~)

## Re: Replaygain, adulterating the signal or not?

##### Reply #1 – 2024-01-07 13:40:00
If original signal is 0.5 dBFS and you aplly  replaygain -1 dB, you will get -0.5 dBFS.
Captain Obvious.

## Re: Replaygain, adulterating the signal or not?

##### Reply #2 – 2024-01-07 13:43:48
The sample sent to the DAC is not the same as the original sample from the music file, the signal has been "adulterated".
And?

So what you're saying is the only way to get an "unadulterated" signal out of any digital reproduction system is to send the music samples direct to the DAC, without any form of scaling.  Try that with floating point!

I think the idea of adulteration should be reserved for spectral or temporal processing, not linear scaling.
It's your privilege to disagree, but that doesn't make you right and me wrong.

## Re: Replaygain, adulterating the signal or not?

##### Reply #3 – 2024-01-07 17:54:35
there's always one or another form of "adulterating" unless you find a way of directly copying sequence of ones/zeros into a human brain (and make it somehow interpret it as desired, too).