If you rip your CDs, you've doubtless noticed that the volume on various discs varies widely. Old CDs are the quietest (particularly ones that were originally mastered for vinyl) and (as has been widely noted) most modern CDs are compressed to hell to make them louder still, since apparently "loud sells." Anyway, the volume difference between any two randomly-selected songs can be quite large, and that's annoying.

There's a program called mp3gain that analyses your MP3s and then adjusts the volume accordingly (and claims to munge the MP3 data in a non-lossy and reversible way.)

There's also apparently a "Relative Volume Adjustment" (RVA2) field in ID3v2 tags as a way of indicating that an MP3 file should have its volume increased at playback-time. There is a "normalize" plugin for xmms that claims to obey this.

So, questions.

• Have any of you used "mp3gain" or the "normalize" plugin?
• Is it a sensible and non-terrifying thing to apply either/both of these en masse to 18,000 MP3 files? Or does it require manual intervention, listening, and tweaking on a per-song or per-album basis?
• mp3gain looks to be Windows/DOS software. Does it work in emulation under Linux?
• Adding the RVA2 tag seems like a safer thing to do than modifying the MP3 data. Does it work as well?