iTunes now allows you to transcode on the fly high bitrate songs when syncing so I don't see much need to keep this going.

I like to rip my CD's in Apple's Lossless format, this will give me the advantage of never having to rip my CD's again EVER! Once I've ripped them all in Lossless format I should be able to then convert them all to any new emerging Lossy format that's flavour of the month in a massive batch job, instead of having to get the discs out again, without loosing any quality.

However I have the problem that I like to rate the songs on my iPhone and sync the rating back to iTunes, so I can then just sync only 3* and over songs on to my iPhone, however at 30 ~ 40 meg per file, a 16gb iPhone is filled pretty quick and if you want to sync just a few songs it also takes an age to sync.

The ideal solution would be to have a Lossless and an AAC/MP3 version of the songs that are synced, so any Meta Data changes on one are updated on the other. So you sync the AAC's to your iPod/Phone and the changes in the Meta Data are sent back to the Lossless version.

Now it's easy enough to create AAC's of your entire library, but if you add some more Lossless files it's next to impossible to tell what has had an AAC version created and what hasn't, and there is no way to sync the Meta Data.

This leads me to the point of this post, I've started writing a VB.Net app for the Windows version of iTunes that will scan your library, create AAC files, get the persistant ID of the Lossless and AAC storing it in a SQLite3 DB along with the current MetaData.

Subsequent sync's would then know what's been converted and skip those tracks and be able to compare the Lossless and AAC Meta Data to the one stored in the DB, updating the relevent file and possibly throwing a question about which direction to do the sync if both sets of Meta Data have changed.

Then I/you can set up a Smart Playlist to sync the AAC files with your iPod.

It's all a bit of a learning cure at the moment but when it's polished enough for a Public Alpha/Beta release ill put a copy in the Downloads section.

UPDATE

I've created the first Alpha release located in the downloads section, all future updates will be appended to the article in the download section, here - http://www.silveragent.co.uk/downloads/5-applications/22-ils-itunes-lossless-to-aac-sync-tool .