Is there a fast way to convert mp3 to mp4?

Do you mean M4A format? That is a common audio equivalent to the MP4 container. MP4 is a video container, not an audio format. Inside the container might be any one of several audio encodings, including MP3, but more likely AAC. Do you have a device that cannot play MP3 files?

u4ick wrote:

All of the attributes assignable from the options choices under get info remain. iTunes default for audiobooks is mp4. In mp3 only remember place remains of all the ones that can be selected.

I don't undersatnd this at all.

Why do you need mp4/aac files?

You still haven't talked about the reason for converting, other than easier to use. I can read between the lines and guess that you are copying the files to some special device that doesn't like MP3,but no idea what it is or why MP3 doesn't work with it. Also, are you settled on using AAC format? I think it is a more advanced format intended to replace MP3 (Haha... sorry, just thinking about how long these PC guys took to give up on Windows XP-- they will fight much harder before giving up MP3 and AVI),

Try Max for conversions. It has a batch feature (drag a dozen files to the window and click the Convert icon). Here is the comparison I got:

Using iTunes to convert a 3:02 length song, 192 kbps, 4.2MB MP3 to AAC 128 kbps, 2.8 MB, the conversion time is 59 seconds.

Using Max (free) to convert the same MP3 to the same setting of AAC 128 kbps, 2.9 MB, the conversion time is 37 seconds.

How slow is "sloooow"? Please mention an example time for an example file size / song length. I just now used iMovie to export an MP3 as MP4 and it took 4 minutes. The original song was 3:02.

u4ick wrote:

Got a large library of audiobooks in itunes that are in mp3 format. I want to convert them to mp4.

Any specific reason you want to convert them?