I wanted to set an excerpt from a DVD as my IPhone ringphone, so I did a bit of research and fighted against the usual IPhone jail-mindset.
There are bits and pieces of information required to transfer an audio file to an iphone as a ringtone, so hopefully this will save someone's time.
The system used is Windows XP and iTunes 8.0.2; this tutorial is meant for average/advanced computer users.
Summary of requirements for a song to be generally set as a ringphone:
* it must be in AAC format, LESS than 128000 kbits/sec (127999 works...) and LESS than 30 seconds (didn't try the exact limit, though)
* the extension must be ".m4r"
Walkthrough for what I've done:
1. identified the chapter in the DVD
2. used SmartRipper, specifying the chapter, and under stream processing, to extract only the audio, in separate files
3. converted the file from .m4a to wave using Winamp (probably this step can be skipped)
4. opened the file using Audacity and removed the unneeded parts
5. converted to aac 127 kbits/sec using Nero AAC Codec
6. copy/paste the resulting file from the folder to the ringphones section in itunes
* If the source is not a DVD, go directly to step 3
* If the source is an AAC file and you're a Mac user, you can use Fission for the lossless editing, that is, to avoid decoding and reencoding; watch out! it's not a free tool.
* When using Audacity, if you want to play with the volume of the track, you can use "apmlify"; an appropriate max amplification has about -4 decibel as peak