LAME ABR quality

All modes
ABR · average bitrate

LAME ABR: what does each --abr target actually produce?

ABR is useful when you want a chosen average bitrate but still want LAME to redistribute bits between passages. These are the measured outputs from the current encoder.

ABR target bitrate versus actual output

--abr asks LAME to target an average bitrate while allowing individual frames to use different bitrates.

Frequency context: the conventional human audible range is about 20 Hz–20 kHz, and CD audio is normally considered to cover that full audible range. A result close to 20 kHz therefore reaches the top of the usual audible-band reference. Frequency reach is only one part of MP3 quality; extra bitrate can also improve how accurately the retained audio is represented.
LAME commandMeasured averageApprox. file sizeHigh frequencies tail off
--abr 9693.9 kbps0.67 MiB/minabout 15.5 kHz
--abr 128125.1 kbps0.90 MiB/minabout 17.1 kHz
--abr 160156.9 kbps1.12 MiB/minabout 17.8 kHz
--abr 192188.7 kbps1.35 MiB/minabout 19.2 kHz
--abr 224221.8 kbps1.59 MiB/minabout 19.9 kHz
--abr 256254.1 kbps1.82 MiB/minabout 19.9 kHz
Example: lame.exe --abr 192 input.wav output.mp3 averaged about 188.7 kbps across the three sources and used about 1.35 MiB per minute.

CBR or ABR?

CBR holds the nominal bitrate fixed throughout the file. ABR can redistribute bits between easier and harder passages while still aiming for the requested average. In this test set, ABR kept broadly the same default high-frequency limits as the comparable CBR rates.

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 these settings

Hear the same source at different ABR settings and switch between them without restarting playback.

The listening test opens with this mode already selected.

Open the ABR listening test

Common questions

What is ABR in LAME?

ABR means average bitrate. LAME varies frame bitrate while trying to keep the whole file close to the requested average.

Is --abr 192 exactly 192 kbps?

Not necessarily. Across these three sources the 192 kbps ABR target averaged about 188.7 kbps.

Is ABR the same as VBR?

No. ABR targets an average bitrate. VBR uses a -V quality target and lets the resulting average bitrate vary with the source.