AVS Audio Converter is a comprehensive tool for converting audio files into the format you need.
There are plenty of utilities that claim to do much the same, of course, but Audio Converter has more than enough power to start out from the crowd, and this starts with its wide format support. It can read MP1/2/3/4, WAV, FLAC, WMA, AAC, OGG, AMR, AC3, AU, AIF/AFF/AIFC, VOX, MPC, MKA, RAW/ PCM/ GSM, MIDI/ MIDI, KAR, APE, QCP, MPA, RA, SHN and VOC files, and then write any of these to MP2/3, MP4, WMA, OGG, FLAC, AAC, or AMR files.
The program is equally at home when extracting the soundtrack from movies, thanks to its excellent video format support: it can read all the main formats, including DVD and Blu-ray video, AVCHD and HDV files, Flash videos and more.
You need more than a simple format conversion? A built-in audio editor allows you to trim, merge or delete sections from your audio files, as well as applying a few effects, ensuring the output file is precisely what you need.
And while you can make this happen in just a click or two, Audio Converter also offers detailed control of the output file, if you need it. So there are channel and encoder settings, configurable high pass and low pass filtering, and much more.
Put this all together and you can even create an M4R-based ringtone for your iPhone; import the audio file you need, edit it down, customise the results with an effect or two, and your custom ringtone will be ready to go.
Please note, the program is subject to a slightly unusual licensing model; registering for $39 gets you use of this program, and the other 17 tools in the AVS suite, for a year; pay $59 and you can use them all forever. Find out more at the AVS4You site.
A powerful audio conversion tool which comes packed with features, yet remains generally very easy to use