Does anybody know whether the "Soundcheck" option in iTunes messes with the music files, or merely adds some kind of tag to them? (The program's help file is very spartan when it comes to describing Soundcheck.)

If it's the latter, how do you remove or edit that tag?

Thanks in advance for your help.

From looking at the tags in Foobar2000 on my iTunes AAC encoded files it appears that iTunes stores this information in the tag of the file. There is an ITUNNORM field in my AAC files which I assume it stands for iTunes Normalization. Since you are given the ability to disable this feature in iTunes the information would have to be stored in the tag so it would be possible to disable the feature during playback.

To remove the tag just open the file in Foobar2000, right-click and select Properties. Select the ITUNORM field and click Remove.

I have mixed feelings about iTunes Soundcheck. It's a nice feature to have included in iTunes as it does, for the most part, normalize your music to a constant volume. However, there are flaws in the way iTunes calculates the volume on some tracks. I have noticed that for shorter tracks that are under 1 minute the volume will be significantly louder than for longer tracks. Also I have noticed that electronica music tends to be louder than pop or rock music when using Soundcheck. I use Soundcheck in iTunes, however, I tag my AAC files with replaygain in Foobar2000 also. For Winamp playback I use the RockSteady normalization plug-in.

Thank you for the detailed reply.

I am aware of the ITUNNORM field you're mentioning in the case of AAC files; I can see it via fb2k too.

The problem is; what's happening with the MP3 files? (99.999% of my collection is encoded in MP3.) Where is that information stored in the case of MP3 files, and how can you view/edit it?

Finally, do we all agree that all iTunes does is add an extra tag, or there's still the possibility that it can mess our files?

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Regarding Soundcheck's overall value: I know it's not something great; I was only testing it while playing with the options in iTunes. (And look what trouble I put myself in now..)

Regarding normalisation, replaygain, etc: until today (5 hours ago, to be precise) I used to replaygain all of my music collection; I decided to stop it, since I listen to most of my music on my portable which doesn't support RG. I'll get back to adding RG info to my collection as soon as it gets portable support (whenever *that* is).

I imagine that iTunes just adds a field to the ID3v2 tag of your MP3 file for its Soundcheck feature. If you view the MP3 file's properties after it has been Soundchecked by iTunes Foobar2000 will probably see the tag in there somewhere.

I'm pretty sure all iTunes does is add a tag to your audio files. It does not mess with the actual audio data because if it did it wouldn't be able to disable the Soundcheck feature if the user requested because the actual audio data would be modified. In that case, iTunes just places a tag on the file so that it can read it or discard it on playback.

I use replaygain because I use Foobar2000 also and it supports it so I'd like to have support for it in at least Foobar. I hope that maybe someday portable devices and more media players will support replaygain but we'll have to see. I am going to be purchasing an iPod in June and I was wondering if the iPod supports the iTunes Soundcheck feature for playback on the iPod. Does it?