ReplayGain

KevinS · Post by **KevinS** » December 7th, 2019, 4:27 pm

TriciaG wrote: ↑December 7th, 2019, 4:19 pm It measures the perceived volume and suggests a number to use to amplify to get it close to 89 dB. (Although I've found it to always return a slightly lower number. Maybe it's aiming for 88 dB rather than 89.)

Thanks!

Post by **philchenevert** » December 7th, 2019, 4:40 pm

I believe Replay Gain was in the analyze tab in earlier versions of Audacity. Now it seems to be in the Effects tab. Perhaps someone knows?

KevinS · Post by **KevinS** » December 7th, 2019, 4:55 pm

philchenevert wrote: ↑December 7th, 2019, 4:40 pm I believe Replay Gain was in the analyze tab in earlier versions of Audacity. Now it seems to be in the Effects tab. Perhaps someone knows?

I've just read about ReplayGain and it would make sense that it be considered an effect rather than simple analysis. Apparently ReplayGain leaves something in the recording so that a media player by its own powers can adjust the volume across a number of recordings and devices.

Folks, I just read it. That doesn't mean I understand it!

Post by **TriciaG** » December 7th, 2019, 5:02 pm

I've just read about ReplayGain and it would make sense that it be considered an effect rather than simple analysis. Apparently ReplayGain leaves something in the recording so that a media player by its own powers can adjust the volume across a number of recordings and devices.

That's MP3Gain, not ReplayGain.

One version of ReplayGain can automatically amplify your recording rather than simply analyzing it. That is probably why they put it in Effects.

KevinS · Post by **KevinS** » December 7th, 2019, 5:58 pm

TriciaG wrote: ↑December 7th, 2019, 5:02 pm
I've just read about ReplayGain and it would make sense that it be considered an effect rather than simple analysis. Apparently ReplayGain leaves something in the recording so that a media player by its own powers can adjust the volume across a number of recordings and devices.
That's MP3Gain, not ReplayGain.

One version of ReplayGain can automatically amplify your recording rather than simply analyzing it. That is probably why they put it in Effects.

Haha! I just read it, as I say.

https://rhmsoft.com/pulsar/help/gain.html

And apparently there is something called MP3 Replay Gain.

Post by **TriciaG** » December 7th, 2019, 6:56 pm

Same name, different animal. According to the guy who wrote the Audacity ReplayGain plugin: https://forum.audacityteam.org/viewtopic.php?p=241658#p241658

This plug-in simply amplifies the audio to a level determined by its "equal loudness" algorithm. It attempts to work out how much amplification is required to make the selected track a "medium" loudness. The algorithm is my version of the Replay Gain algorithm as described here: http://wiki.hydrogenaudio.org/index.php ... ReplayGain

If you want the "real" Replay Gain see here: http://wiki.hydrogenaudio.org/index.php ... ReplayGain

LAM wrote:2 - Is it using compression?
My plug-in just uses amplification and not compression.

LAM wrote:2 - Does replaygain fix clipped peaks?
No it doesn't.

Post by **philchenevert** » December 7th, 2019, 7:13 pm

Hot ziggedy Dog. This is a fun discussion. My question is how does the Replay Gain effect in Audacity know about 89dB? The preset shows it as adjust ing normalized output to 0 dB. In one case recent ly it was set to -3 dB which is what I believe most audio people use to assure enough volume.

So my question is if this effect is determining how close the section is to 89dB when it analyzes, or to some other preset level. Am I making sense here?

lurcherlover · Post by **lurcherlover** » December 8th, 2019, 2:51 am

philchenevert wrote: ↑December 7th, 2019, 7:13 pm The preset shows it as adjusting normalized output to 0 dB. In one case recently it was set to -3 dB which is what I believe most audio people use to assure enough volume.

In professional circles -3dB is the minimum headroom which an audio file must have. This is to protect against clipping, as some clipping can happen with files that have a smaller headroom. The 89dB level is just a level which LV aims for but it has no relevance outside of LV. (It equates roughly to -11dB so it's not as "hot" as -3dB). By the way, the headroom levels measurements on Audacity *may* be less accurate than the professional DAWS in use generally. I have as a plugin another (LUFS) meter which corroborates the readings of the Reaper meter. The Reaper meter is within 1dB of the LUFS meter.

tovarisch · Post by **tovarisch** » December 8th, 2019, 7:11 am

I think with the discussion of normalizing to -3 versus replay gain to 89 you miss the fact that "replay gain" is not a single measurement of the largest sample, it's an integral characteristic. The normalization to -11 dB will NOT give you 89 dB of "replay gain", neither will normalization to any other value because the "replay gain" depends on the distribution of the samples in your track. Example: record everything very low, except one loud (even clipped) bang/shout, and normalization will drive everything even lower, while replay gain will tell you that you don't have enough "volume" overall.

lurcherlover · Post by **lurcherlover** » December 8th, 2019, 7:51 am

So that's basically what LUFS is, an overall measurement of the whole file.

Post by **philchenevert** » December 8th, 2019, 8:18 am

My question is: how does the Replay Gain effect in my Audacity 'know' about 89dB that we use here is LibriVox? When it analyzes my file and tells me it needs 2 dB more or -2dB less, how does it know that the referent point is 89dB? That is my question. Where is this number 'set' into the program.

GrayHouse · Post by **GrayHouse** » December 8th, 2019, 8:50 am

philchenevert wrote: ↑December 8th, 2019, 8:18 am My question is: how does the Replay Gain effect in my Audacity 'know' about 89dB that we use here is LibriVox? When it analyzes my file and tells me it needs 2 dB more or -2dB less, how does it know that the referent point is 89dB? That is my question. Where is this number 'set' into the program.

The 89dB is part of the ReplayGain standard. The level was chosen by adapting a similar standard that already existed for television and motion picture playback.

I think a point of confusion arises in many people because 89dB doesn't appear to match the dB levels you see on the waveform axes in Audacity where the dB levels are negative numbers. Those numbers are often called "dB full scale" - and they obviously tell you how much margin you have before your audio clips. In constrast the 89dB uses a completely different dB scale based on sound pressure level. There are hundreds of different decibel scales which are used for many different applications. Decibels are relative units - you have to know what scale is being used for any particular measurement.

-Ian

Post by **philchenevert** » December 8th, 2019, 9:01 am

Thank you Ian. So it is just the preset standard for this program. Cool.

schrm · Post by **schrm** » December 9th, 2019, 9:13 am

actually, in the linux version there is a "add plugin" line in every menue item. and after you downloaded the plugin, copied it in a folder and added it under "analyze", it is there!

rieyrules · Post by **rieyrules** » December 9th, 2019, 3:13 pm

You guys really make me laugh!! One thing I can't understand: there are so many things that ARE included in Audacity; why is Replay/Gain NOT included? Probably more complicated than my pea-brain can comprehend. Phil, I love your videos- very informative, very amusing, and (usually) answer all of my questions! Still so much to learn...
Laura