Bitrate Settings

constant Bitrate: LAME creates an output mp3 in which every frame has a constant bitrate.

average Bitrate: LAME chooses a bitrate in the near of the mean bitrate for every frame, taking into account how many bits it takes to encode a particular frame.

variable Bitrate: lets LAME encode every frame with a bitrate that stays between the minimum and maximum bitrate.

Bitrate / mean Bitrate / min. & max. Bitrate: lets you set the bitrate or bitrate range the LAME encoder should use.

Variable Bitrate Settings

VBR Method: lets you select the algorithm LAME will use for variable bitrate encoding.
new: the new VBR algorithm; recommended to use
old: old VBR algorithm

VBR Quality: the quality to use for VBR. Lower values yield to better quality.

enforce minimum Bitrate: LAME enforces the minimum bitrate, which is normally violated for passages of music with absolute silence.

write "VBR Info" tag: when using VBR, LAME can write a special info tag at the start of the mp3 file. The tag contains various infos about the encoder settings, as well as a frame bitrate histogram. VBR Info tag aware players can correctly seek and compute playing times when this tag is written. Note that the Info tag is omitted when using nogap encoding. The VBR Info tag was previously called Xing tag.

free format Bitstream: normally LAME produces a mp3 bitstream where every frame has a certain bitrate. To override this and use any bitrate you wish, check this box. Only available for constant bitrate (CBR).
Note: most portable mp3 player cannot handle a free format bitstream mp3 file!

Samplerate: lets you specify the output frequency of the mp3 file. As this frequency is tied to the MPEG type, you also may get another MPEG type.
Note: some players cannot handle MPEG2.5!
Note: choosing 48 kHz for ripped CD wave files (which normally have 44.1kHz sample rate) slows down encoding and decreases quality, due to resampling.

Algorithm Quality: lets you choose the quality (and speed) of the LAME encoder. At bigger quality values, some algorithms are switched off, which results in higher speed, but produces less quality. If unsure what to take, choose algorithm quality 2, the default.

Channel Mode: lets you choose the channel mode:
Stereo: every channel is encoded separately, although LAME may spend more bits on a harder to encode channel.
Joint Stereo: the two channels are compared and only differences in both channels are encoded. This saves some bits that can be used for better quality. Recommended when the audio file has little stereo separation.
Force Mid/Side: this forces LAME to use Joint Stereo on every frame in the mp3 file, even when it may not make sense.
Mono: LAME mixes all channels to one and only encodes this one.

prepend RIFF WAVE Header: when checked, writes a RIFF WAVE Header before the mp3 file, the output file extension is ".wav". The resulting mp3 compressed wave file can be used in various applications (such as VirtualDub) that only can use wave files for input.

mark as original: marks the output file as being original

mark as copyrighted: marks the output file as being copyrighted

error protection: turns on CRC error protection. It will add a cyclic redundancy check (CRC) code in each frame, allowing to detect transmission errors that could occur on the MP3 stream. However, it takes 16 bits per frame that would otherwise be used for encoding, and sound quality will be slightly reduced.

strict ISO bitstream: when set, LAME will enforce the 7680 bit limitation on total frame size. This results in many wasted bits for high bitrate encodings but will ensure strict ISO compatibility. This compatibility might be important for hardware players.

disable bit reservoir: disables LAME's internal bit reservoir when set. Each frame will then become independent from previous ones, but quality will be lower.

Filter Settings

use lowpass filter: enables lowpass filtering of input files. Cutoff Frequency is specified in Hz. As one normally cannot hear higher frequencies, no bits are used for those frequencies filtered.

disable all filters: tells the encoder to use full bandwidth and to disable all filters. By default, the encoder uses some highpass filtering at low bitrates, in order to keep a good quality by giving more bits to more important frequencies. Increasing the bandwidth from the default setting might produce ringing artefacts at low bitrates. Use with care!

ATH Settings

disable ATH: disables any use of the ATH (absolute threshold of hearing) for masking. Normally, humans are unable to hear any sound below this threshold. Disabling use of this feature might be usefull for music recorded at extremely low level.

only use ATH: this option causes LAME to ignore the output of the psy-model and only use masking from the ATH (absolute threshold of hearing). Might be useful at very high bitrates or for testing the ATH.

lower the ATH: lower the ATH (absolute threshold of hearing) by n dB. Normally, humans are unable to hear any sound below this threshold, but for music recorded at very low level this option might be useful.

Other Encoder Settings

disable temporal masking effect: disables the psychoacoustic model option when checked

See also:
Working with Movkit DVD Ripper Pro