FreeTrim MP3 can convert an audio file’s bit rate or number of channels. This change applies to the whole file (you cannot change just parts of the file).
To convert the sample rate of the current file you should select an output format from MP3, WMA, WAV & OGG. Then, use “Settings…” to select the new bit rate and channel. The bit rate must be between 32 and 320 kbps. Typical bit rates are displayed in the pull down list. If you are not familiar with the parameter setting, you can apply the presets provided.