What does changing the Reference Level of ReplayGain change?

scooterbaga's Avatar


26 Aug, 2017 04:54 PM


I'm having trouble nailing down what the different Reference Levels actually accomplish outside of overall volume level of a given track. Can we get some examples/explanations on what differences one might hear when using the ATSC level vs the Mobile level for a given set of files? Thanks.

  1. Support Staff 1 Posted by hendrik on 27 Aug, 2017 11:23 AM

    hendrik's Avatar

    Let's assume a completely fictitious example:

    The algorithm measure that your music is 80 units loud.
    The reference level is 100 units.
    This means the difference is 20 units.

    So when playing the song with replay gain support turned on, the player will make the song 20 units louder, so that the reference level is reached.

    What's stored in your files is just the 20 units, not the 100 or the 80.

    So depending on what you chose as a reference level at analysis time, the player will make your files sound quieter or louder (if replay gain support is turned on).

    Does that explain things?

  2. 2 Posted by scooterbaga on 27 Aug, 2017 02:08 PM

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    I think that makes sense. So the Reference Level is a form of "absolute" or
    "actual loudness" and the Analysis adjusts the individual volume of a given
    file to *sound* like the file is at that volume.

    What does the Reference Level "Mobile" mean?

  3. Support Staff 3 Posted by hendrik on 27 Aug, 2017 05:52 PM

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    You might want to read https://auphonic.com/blog/2013/01/07/loudness-targets-mobile-audio-... for a decent explanation.

  4. 4 Posted by scooterbaga on 29 Aug, 2017 12:33 PM

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    Quoting the bit that was relevant for me:

    Is -23 LUFS loud enough for podcasts and mobile audio?

    EBU R128 was primarily devised for television, but podcasts are often consumed on lower-quality audio systems and in noisier environments. So how does the -23 LUFS value perform under these circumstances?

    At Auphonic, we have conducted some informal trials to answer this question. We have simply done what many people do: listen to podcasts on laptops, cellphone loudspeakers and headphones while simultaneously conducting everyday activities such as cooking or using public transportation. To us it seemed that a loudness of -23 LUFS is not sufficient under these circumstances. Most noticeably, speech intelligibility clearly suffers at that level and many hardware players don't provide enough gain to make the audio loud enough. Thomas Lund also concludes that -23 LUFS "is too low for pod/mobile platforms". He proposes the following distribution levels, which correspond well to our own experience:

    • For podcasts: -16 to -23 LUFS
    • For mobile audio: about -16 LUFS

    See his great article Audio for Mobile TV, iPad and iPod for detailed information and practical tests regarding loudness on mobile devices. Furthermore a new Music Loudness Alliance group tries to establish a loudness metadata system similar to Sound Check or ReplayGain which is enabled by default. Then all audio which is too loud, or without metadata, will be punished automatically.

    According to this, I'd suggest changing the name of that reference level to something like "Everyday Use" instead of Mobile. Mobile sounds like something specifically for mobile devices as opposed to a general use standard.

    Perhaps even consider making the ReplayGain2 or Mobile (or -17 LUFS) the default reference level. Perhaps also making True Peak a default as well.

    I'd also consider rewording the sidebar info to mention that ATSC and EBU are basically lower loudness broadcast standards and that "normal" usage loudness is closer to -16 LUFS. Right now the sidebar makes ATSC and EBU sound like the most desirable choices.

    Thanks for your time on this!

  5. Support Staff 5 Posted by hendrik on 30 Aug, 2017 06:20 AM

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    Thanks for posting the excerpt.

    For me the most important aspect was always: Keep the level the same across your whole music collection.

  6. 6 Posted by Tekl on 12 Nov, 2017 07:15 PM

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    Interesting may be for some people, that Apple uses -16 LUFS and other streaming services use -14 LUFS. Spotify changed from -12 LUFS to -14 LUFS this year. Also YouTube uses -14 LUFS. If you mix multiple music sources, you could use -14 LUFS. If you live in the Apple world, -16 LUFS could be the best choice.

    Well, assumed, that the different algorithms are comparable.

  7. Support Staff 7 Posted by hendrik on 13 Nov, 2017 10:23 AM

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    Interesting... Where is this information from?

  8. 8 Posted by Tekl on 13 Nov, 2017 12:29 PM

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  9. Support Staff 9 Posted by hendrik on 13 Nov, 2017 12:33 PM

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    Awesome. Thank you!

  10. 10 Posted by hmijail on 07 Jun, 2021 01:25 PM

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    This discussion made me understand why I might be seeing volume weirdness in my library.

    IMO, it'd be very useful to have a hint in the Analysis options dialog mentioning that, as Tekl mentioned, the Music.app level is about -16 LUFS.

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