Everyone,
The next build of MC contains modifications that should resolve issues regarding Replay Gain. The solution will have the following limitation....
The conversion from Replay Gain to iPod volume adjustment uses the formula Gain * 50 / 6 to convert to a -100 to 100 point scale. Any adjustments outside of this range will default to the 100 point maximum so it will be capped at a certain point.
There was a bug that is fixed so things should be better now.
Thanks,
Steve
Steve, ReplayGain values can be converted to values that the iPod can use when you turn on the SoundCheck functionality. You don't have to use the volume field on the iPod.
Specific information about how to put this into the mhit correctly can be found here:
http://ipodlinux.org/ITunesDB#Track_ItemBut basically, instead of writing some imprecise value into the volume field, you write it into the soundcheck field, which starts 12 bytes after the volume field. The conversion is as follows: Soundcheck field value = 1000 * 10 ^ (-.1 * ReplayGain dB value). This is the exact conversion, not an estimated one.
Anyway, the upshot of doing it this way is that ReplayGain values will be used whenever "SoundCheck" is enabled in the iPod's settings. This also allows users to use the volume field for individual song adjustments, as well as letting them turn off ReplayGain on the fly if they so desire.
The iPodLinux wiki is where I keep all this information at, but feel free to email me if you have any questions about specifics on the iPod's file formats.
-Otto