ReplayGain and Apple Music Sound Check

[brnfox]

Hi,
I recently added 2 songs from different sources (Bandcamp and iTunes Store) to create an album I play in Apple Music on macOS Sequoia 15.4.1
I used Replay Gain with the recommended settings:


And I have a problem: the second song play quieter than the first in Apple Music, it's ok when I play these songs via PerfectTUNES ID Tags or QuickTime Player.
If I configure Sound Check to off in Apple Music, it's ok but I thought Sound Check have to be on to use ReplayGain tags, I misunderstood ?
Thanks for your help.
Bruno

[garym]

My understanding is that Apple Music does not use ReplayGain values. It only uses SoundCheck values. And yes, you can write ReplayGain values *and* Soundcheck values with dbpa.

[schmidj]

Gary, I think you are basically correct regarding Soundcheck, Apple's proprietary equivalent of replay gain. Some have said that it only does track gain, but at least when calculated by Apple, they claim to handle both track and album gain. How with a single number in the tag???

The linked Apple document, written for mastering engineers, is a good read. Scroll down quite a ways to get to Soundcheck and Volume Normalization. It is incorrect on one detail, it seems to imply that Replay Gain Volume Normalization only is for mp3 files, which, of course, is incorrect. It will work for any audio filetype which has metadata able to save the tag(s), if played on a (non-Apple) playback device/software which can apply the replay gain tag and adjust its output level accordingly.

https://www.apple.com/apple-music/apple-digital-masters/docs/apple-digital-masters.pdf

[garym]

schmidj agree. Soundcheck is only track typically if created by itunes. . However some programs can create soundcheck tags from ReplayGain values and thus use either TRACK or ALBUM RG values based on a setting. I use an action in mp3tag to create soundcheck tags based on ALBUM replaygain tags. Or at least i used to. Now i use foobar2000mobile on my iThings and it can read replaygain tags (and FLAC files too!)

[brnfox]

Thanks for your replies.
As said, I use ReplayGain and I have the itunnorm tag on my songs. What I don't really know is if I have to check or not Sound Check in Apple Music settings so that Apple Music takes in account this tag...

[garym]

Thanks for your replies.
As said, I use ReplayGain and I have the itunnorm tag on my songs. What I don't really know is if I have to check or not Sound Check in Apple Music settings so that Apple Music takes in account this tag...

Yes. Tick Soundcheck in apple music and it will use your itunnorm value.