Replay Gain

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crobannon
Posts: 5
Joined: Fri Aug 04, 2017 10:48 am

Replay Gain

Post by crobannon »

My research has me concluding that what I really want is "Replay Gain" to make perceived volumes equal. Here is a quote from an article:

"ReplayGain is the name of a technique invented to achieve the same perceived playback loudness of audio files. It defines an algorithm to measure the perceived loudness of audio data.

ReplayGain allows the loudness of each song within a collection of songs to be consistent. This is called 'Track Gain' (or 'Radio Gain' in earlier parlance). It also allows the loudness of a specific sub-collection (an "album") to be consistent with the rest of the collection, while allowing the dynamics from song to song on the album to remain intact. This is called 'Album Gain' (or 'Audiophile Gain' in earlier parlance). This is especially important when listening to classical music albums, because quiet tracks need to remain a certain degree quieter than the louder ones.

ReplayGain is different from peak normalization. Peak normalization merely ensures that the peak amplitude reaches a certain level. This does not ensure equal loudness. The ReplayGain technique measures the effective power of the waveform (i.e. the RMS power after applying an "equal loudness contour"), and then adjusts the amplitude of the waveform accordingly. The result is that Replay Gained waveforms are usually more uniformly amplified than peak-normalized waveforms."

However, I do not see this in GoldWave. Does GW have it under a different name?
DougDbug
Posts: 2172
Joined: Wed Feb 16, 2005 3:33 pm
Location: Silicon Valley

Re: Replay Gain

Post by DougDbug »

GoldWave has something similar called "Loudness". It's based on a published standard called EBU R128.

The "real" ReplayGain doesn't touch the audio files so it's not appropriate for GoldWave.

ReplayGain is built into some audio player software. (Apple uses something similar called Sound Check.) The files are pre-scanned for loudness, and the ReplayGain volume adjustment is applied by the player when the file is played. I use ReplayGain in Winamp, but Winamp is old and is no longer supported.

There are variations such as MP3Gain and WAVEgain. These do "permanently" adjust the volume of the files so they work on any player.

NOTE - Most songs, including many quiet-sounding songs are already peak normalized (AKA "Maximized") so they can't be made louder to match your louder songs (unless you push them into clipping/distortion). So, in order to match volumes you have to make the loud songs quieter.

ReplayGain has a default target volume to accommodate most songs, but some quiet-songs will still be too quiet. It's a compromise... If you wanted to volume-match the quietest-songs you'd have to turn-down everything else even more.

If you have a limited number of songs (say 10 or 20 songs for a CD) you don't have to guess the target volume and you can take a different approach...

- Maximize all of the songs.
- Check the loudness of all songs and choose the quietest one as your reference.
- Adjust-down the other songs to match.
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