Fixed Bitrate Compression

See also: Compression | Variable Bitrate Compression | Audio Formats

AKA: CBR – Constant Bit Rate

A type of lossy media compression that uses the same data per second throughout the entire audio/video file. This is useful to allow Internet visitors to download and play simultaniously.


The vast majority of Internet music is encoded in MP3 format at 128 kilobits per second and therefore MP3 is used in this comparison. 128 kbits are suitable for streaming over an ISDN or faster Internet connection. As MP3 is an old format, other formats such as Ogg Vorbis, RealAudio, and MP3Pro will have generally better quality than MP3 and will have better results at all bitrates.

(Note: ratings are based on Blade MP3 encoder ( Different MP3 encoders will have varying quality.)

Some common bitrates for voice recordings (mono, not stereo). In kbit:

  • 24 – sounds scratchy and computerized, like AM radio, extreme compression ratio of approximately 1:80 from original wav file.
  • 56 – clear, smooth compression for most voices while keeping good compression (about 1:50 size ratio from original wav file).
  • 64 – suitable for soft music background with voice. Music will sound hollow and/or flat.

Other common bitrates for music include:

  • 96 – sounds fine on poor quality audio equipment but very flat otherwise.
  • 112 – better than radio quality.
  • 128 – CD quality to the untrained ear or on poor equipment, some music beats still sound softened.
  • 160 – A great level to archive rarely heard but still enjoyed CDs.
  • 192 – Most audiophiles exchange audio at this bitrate with the best quality versus transfer time.
  • 256 – Almost indistiguishable from original CD.

Note that Variable Bitrate Compression is usually a better option. The “Average bitrate compression” is recommended for streaming.

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