Use ReplayGain?

[audiobomber]

I've read about replaygain on the net and I'm not sure whether it is a good thing or not. They say it is not "bit perfect". I would like to hear an explanation of how it affects the bits and whether this is a theoretical compromise or an actual sonic compromise. TIA!

[esldude]

3 hours ago, audiobomber said:

I found a good Wiki. https://wiki.hydrogenaud.io/index.php?title=ReplayGain_2.0_specification

 

So replaygain adjusts tracks to -14dB based on rms level. If the track has peaks beyond 14dB, then it will limit the peaks. Wouldn't that be the only time it is not bit-perfect?

Bit perfect means each sample has the same exact value it started out with.  So if I increase level or decrease level by even 1 db, the value of all samples changed (the bits have changed).  Now done in software that works at 32 bit or 64 bit float that has zero effect on the sound quality other than level.  Yet it isn't bit perfect. 

 

I thought I remembered that replay gain could do other things besides level changes.  So yes when they slightly compress or limit peaks to prevent clipping while hitting a target of - 14 db the sound of a file will have been changed as a result.  Which is why audiophiles would never use Replay gain.  

[esldude]

You'll lose all your audiophile credentials if you use replay gain.  You may not ever get them back either. 

 

What does it do?  Well you know how this track is pretty loud and the next one is really low and needs turning up.  Well replay gain adjusts the gain and tries to make all tracks you play have the same basic subjective loudness so you don't have to mess with the volume setting all the time when random playing from many sources.  It is not bit perfect, because it changes gain and thereby changes bits.  

 

The way it works is to analyze the entire track, pick a gain that won't clip, but sounds like an appropriate level of loudness.  It works okay.  I use it sometimes for casual background use.  For CRITICAL listening I don't.  I think it probably is some sonic compromise, but I've not investigated it thoroughly.  

 

So use it when it suits you and skip it if it doesn't.  No permanent harm is done, and you can always turn it off.  I often use Foobar for playback and you can turn it on or off.  

 

But keep it on the QT.  I didn't say this, and you aren't going to use it because neither of us want to lose our audiophile credentials.  My lips are sealed.  

[StephenJK]

My understanding is that it was intended to reduce or eliminate amplifier clipping in the event of a sudden jump in volume.  It simply adjusts the peak and gain of the track with data stored in meta format with the file - it doesn't actually change the music in any way except with the volume.  You do need software or a player that has Replay Gain enabled.  

 

I looked into it years ago when I started ripping CDs and discounted it as an option for two reasons.  First, I didn't want the metadata to be changed from what was already there and more importantly I wanted to listen to the music the way it was recorded - for right or wrong.

 

I live with music libraries where anytime I play a CD after an LP there's a big jump in volume - but I know that and can easily adjust for that.  

[audiobomber]

On 5/8/2019 at 1:23 AM, esldude said:

The way it works is to analyze the entire track, pick a gain that won't clip, but sounds like an appropriate level of loudness. 

I found a good Wiki. https://wiki.hydrogenaud.io/index.php?title=ReplayGain_2.0_specification

 

So replaygain adjusts tracks to -14dB based on rms level. If the track has peaks beyond 14dB, then it will limit the peaks. Wouldn't that be the only time it is not bit-perfect?