How to use your iPhone media library on 2 comps simultaneously

And yet another post in the "why can't things simply work" category. I should probably add that category officially... Again I wanted some very special, exotic functionality from a software. This time it was iTunes (again) and the rediculous thing I wanted was to manage my iPhone music files manually from 2 comps. So I installed iTunes on a second comp and even unlocked it. 2 of 5 activations left, that's fine with me.

But as I tried to access the iPhone's music library, I got a message from iTunes telling me that the iPhone can only be synched to one Music Library at a time and if I wanted to sync it with this "new one", then all Media on the phone will be removed first. WTF?

I get the idea behind the iTunes Media Libraries and the approach they've chosen. But honestly, is it really that extraodinary to want to use your iPhone from 2 comps at the same time? Usually I just wanna copy over the one or the other file, song, video or delete some media files on the phone that I don't really need. I see why iTunes would complain if I had set it to keep the whole library synched, but if I check the "manage manually" option in iTunes, I don't wanna see a limitation like that.

After googling, I saw that I'm not the only one who would like to use that feature. And I stumbled over a solution too. It's quite easy and cheap:

http://www.andrewgrant.org/2008/03/30/how-to-sync-an-iphone-with-two-or-more-computers.html

Seems like every iTunes-installation creates a unique key for its media-library. If an iPhone is connected, it checks if that ID is equal to the one of the media library on the iPhone. If it's not, it won't allow you to modify the library on the phone. So all you need to do is to find 2 specific files and to replace the ID contained in those with the one of your previous installation. So then both iTunes Libraries have the same ID and voila, it works. It doesn't matter that the libraries don't contain the same files, but that's alright since all it does is to check the ID. And since I don't want to sync my whole library that way on two comps (since they are in different places and can't access the same files), I'm good.

Hmm, and just as a thought: By actually copying over those two files from one installation, you could probably duplicate your library on two iTunes installations easily - you just gotta make sure that the paths associated for the files themselves are identical on both machines. There might be additional files needed, like the CD-covers downloaded or so, but that's easy to figure out. Note to self: try this out one day.

Thanks go to "A blog by Andrew Grant", where I found the original idea (see the link above)