Input is raw PCM: enable this if your input files contain RAW audio data with no RIFF (.WAV etc) headers. When enabled you must also specify the input's sampling frequency 'cause Lame can't detect it without RIFF headers (oh really).

force Byte-Swapping: enable this if your raw input files were created with Motorola's byte-order. (e.g. files from Amiga and Mac)

downmix to mono: guess what.

delete source files: after encoding/decoding the source files will be deleted. For safety measures, a confirm requester has been added to the en-/ decoding if this checkbox is activated.

disable all filters: Lame uses a low-pass filter per default in order to make the MP3s sound better. If you don't want it, disable it.