Overriding default settings

 Many of the following features override the encoder's idea of best-quality settings. You should be aware that overriding the encoder default settings is something for experts. You might wreack the encoding quality in a number of ways without first noticing it. Also, the encoder is not guaranteed to run at all parameter combinations. Proceed at your own risk!

-k 
Tells the encoder to use full bandwidth. By default, the encoder uses a 16kHz bandwidth up to 64kbps per channel, and full bandwidth at higher bitrates. Increasing the bandwidth from the default setting might produces ringing artefacts at low bitrates. Use with care!
-O 
Uses the original ISO psycho-acoustic model instead of GPsycho. Used with -m s, it will produce the same output as the ISO code or the encoders based on it, like 8Hz, Blade or Lame 2.x
It will reduce a lot the quality and should only be used for comparison tests.
 

Tids & bits

-a 
This switch tells the encoder to autoconvert a stereo input signal into one channel, producing mono output. The downmix is calculated as the sum of the left and right channel, attenuated by 6 dB.
-f 
This switch forces the encoder to use the "extra fast" encoding mode. It will reduce a lot the quality of the output. This might be useful for real-time processing or streaming on slowest computers.