I did this, so I thought there might be someone else out there who is interested. I have a 64gb 4th generation iPod Touch. I missed having all my music on it as I did with my old iPod Classic. You might not describe me as an audiophile but I do consider myself picky about sound. I discovered that files encoded at 64 kbps on the high-efficiency AAC setting sound very good, in fact very difficult with my slightly-damaged hearing to distinguish from files encoded at 256 kbps. So this is what I did, and what you can do:
1. Make sure you have plenty of extra space on your hard drive. For my method, which involves creating a second music library, you'll need about 1.5 times the amount of space your present music library uses. For the alternate method, you just need enough space for the new lower-bitrate files.
2. Create a new iTunes library. You do this by holding down the option key on a Mac while opening iTunes. There's a different command for PC's which I don't know off hand. The first time you do this you'll see an option to create a new library and give it a name. I called mine "iTunes Compressed." Once you have multiple libraries, iTunes will stick with the most recently opened library unless and until you start iTunes again, holding down the option button, upon which you will get a prompt to choose which library you want.
3. Import all of your music into the new library. You do this by using the "add folder to library" command. When you do this, iTunes makes copies of the files in the new library. This will take a few hours if you have a big library.
4. Decide on a file format for the compressed files. As stated above, I used 64 kbps high-efficiency AAC. You can select this option under the iTunes preferences for importing.
5. Then comes the fun part. Highlight all the tracks you want to create compressed versions of, right click, and select "create AAC version." If you have any old files that have any sort of restrictions on copying (DRM, remember that?), try to get rid of them before you start the process because when iTunes is creating the new versions the process will be halted if it encounters a file that can't be copied. Also, don't do your whole library at once, because your computer is likely to totally freak out. I recommend organizing your music alphabetically and doing it by letter of the alphabet, e.g. convert all the artists starting with "A,", then "B," etc. If your computer doesn't get overloaded, you can start doing 2 or 3 letters at a time. This whole process took me a few days of starting and stopping and at least a couple of overnight operations. You will end up with two of every file in your new library, the original-sized one and the compressed one.
6. Delete all of the big sized files by sorting your library by file size, so that you are left with only the compressed files. I believe you can also tell iTunes to move the files themselves to the trash, because it is only deleting the copies that were made in the new library. But you should experiment with this first by deleting just a select track or tracks and verifying that your original file is still in your original library.
7. Now your new library only has the compressed files, so you can sync your iPod with that library and everything will fit on the iPod. I had to also do a complete restore of the iPod, which meant I had to re-load apps also.
The alternate method would be that you can just make the duplicates without creating a new library. The problem with that is that your library will have two copies of everything, and you'll need to make playlists to separate out the songs by file size.
FYI, the 21,000+ songs take up about 40 gb.
Let me know if there are comments or questions.
1. Make sure you have plenty of extra space on your hard drive. For my method, which involves creating a second music library, you'll need about 1.5 times the amount of space your present music library uses. For the alternate method, you just need enough space for the new lower-bitrate files.
2. Create a new iTunes library. You do this by holding down the option key on a Mac while opening iTunes. There's a different command for PC's which I don't know off hand. The first time you do this you'll see an option to create a new library and give it a name. I called mine "iTunes Compressed." Once you have multiple libraries, iTunes will stick with the most recently opened library unless and until you start iTunes again, holding down the option button, upon which you will get a prompt to choose which library you want.
3. Import all of your music into the new library. You do this by using the "add folder to library" command. When you do this, iTunes makes copies of the files in the new library. This will take a few hours if you have a big library.
4. Decide on a file format for the compressed files. As stated above, I used 64 kbps high-efficiency AAC. You can select this option under the iTunes preferences for importing.
5. Then comes the fun part. Highlight all the tracks you want to create compressed versions of, right click, and select "create AAC version." If you have any old files that have any sort of restrictions on copying (DRM, remember that?), try to get rid of them before you start the process because when iTunes is creating the new versions the process will be halted if it encounters a file that can't be copied. Also, don't do your whole library at once, because your computer is likely to totally freak out. I recommend organizing your music alphabetically and doing it by letter of the alphabet, e.g. convert all the artists starting with "A,", then "B," etc. If your computer doesn't get overloaded, you can start doing 2 or 3 letters at a time. This whole process took me a few days of starting and stopping and at least a couple of overnight operations. You will end up with two of every file in your new library, the original-sized one and the compressed one.
6. Delete all of the big sized files by sorting your library by file size, so that you are left with only the compressed files. I believe you can also tell iTunes to move the files themselves to the trash, because it is only deleting the copies that were made in the new library. But you should experiment with this first by deleting just a select track or tracks and verifying that your original file is still in your original library.
7. Now your new library only has the compressed files, so you can sync your iPod with that library and everything will fit on the iPod. I had to also do a complete restore of the iPod, which meant I had to re-load apps also.
The alternate method would be that you can just make the duplicates without creating a new library. The problem with that is that your library will have two copies of everything, and you'll need to make playlists to separate out the songs by file size.
FYI, the 21,000+ songs take up about 40 gb.
Let me know if there are comments or questions.