LAME Quality Settings: CBR, ABR, VBR, cVBR and cVBRb

Measured LAME 4.0 output

What do the LAME quality settings actually produce?

Choose a mode below to see the average bitrate, approximate file size per minute and high-frequency reach produced by the current encoder.

Choose an encoding mode

Each page uses the same three measured outputs so the settings can be compared without needing to understand encoder internals.

CBR · -bFixed bitrate. See how 96 to 320 kbps changes file size and top-end response. ABR · --abrTarget an average bitrate while allowing LAME to vary frame bitrate. VBR · -VV0 to V9 measured, including V3 / --r3mix and V0 / legacy extreme. cVBR · -V + -bVBR quality target with a strict minimum bitrate floor. cVBRb · boostThe constrained mode with additional bitrate boost for demanding audio.

What the tables answer

Average bitrateWhat the current encoder actually produced from the three test sources.

File sizeApproximate MiB per minute, measured from the generated MP3 files.

High-frequency reachWhere the default high-frequency response effectively tails off, with 20 kHz as a useful reference for the top of the conventional audible range.

How to read the frequency figures

Useful reference: the conventional human audible range is about 20 Hz–20 kHz, and CD audio is normally considered to cover that full audible range. Values near 20 kHz therefore reach the top of the usual audible-band reference. A wider frequency range does not by itself mean a better MP3; bitrate is also used to encode the retained audio more accurately.

How these figures were measured

Each setting was encoded with the current LAME 4.0 build against the same three stereo WAV sources. Average bitrate is the mean of the three encoder results. File size is normalized to MiB per minute so clips of different lengths can be compared fairly. The high-frequency figure is the approximate point where the default encoder response has effectively tailed off.

Erokia synthBroad-range electronic material with strong low-frequency content.

Usilaya orchestral stringsSustained tonal material used for weight and steady-state comparison.

astro_denticle breakbeatTransient and high-frequency material useful for top-end behaviour.

The three source WAV files are CC0 material from Freesound: Erokia 524947, Usilaya 546205, and astro_denticle 846944.

Listen to the quality settings

Use the synchronized listening player to compare the original source with CBR, ABR, VBR, cVBR and cVBRb encodes at the same playback position.

Choose a source, choose a mode, then switch quality or bitrate while the passage continues.

Open the LAME MP3 quality listening test

Common questions

Which LAME mode should I use?

VBR is a useful general-purpose choice when quality is the priority. CBR gives predictable bitrate and size, ABR targets an average, while cVBR and cVBRb add bitrate constraints to VBR.

Are the file sizes estimates?

The MP3 file sizes were measured from the generated files and normalized to MiB per minute so the three source clips can be compared fairly.

Does a higher bitrate always extend the frequency range?

No. Some adjacent settings share the same default high-frequency limit; additional bitrate can instead be used to encode the retained spectrum more accurately.