Apple recently released iTunes 9.1, and while the biggest change is support for the Apple iPad and iPad apps, there’s another tweak that can make life easier for iPod and iPhone users. Hidden away in the options menu for your mobile device is a new option to convert higher bit rate songs to 128 kbps AAC files before syncing them with your iPhone or iPod.
In other words, if you have a lot of songs encoded at 256kbps but only have 7GB of storage space on your mobile device, you can fit about twice as much music on your iPhone or iPod by transcoding the audio. Sure, songs won’t sound quite as good at 128kbps, but the difference isn’t as great as you would think. What you probably don’t want to do is reduce the bit rate to 64kbps…
Of course, if your iPhone storage is occupied primarily by apps or videos, this probably won’t reclaim much space at all.