Bit rate - what is?

Bitrate is the average number of bits that one second of audio data will 
consume. Standard MP3 bitrates are 64 Kbps (kilobits per second), 96 Kbps, 
128 Kbps, and 160 Kbps. 

Different bitrates yield MP3s of varying sound quality. The higher the
bitrate, the more times per second the original sound is sampled, thus
yielding a more faithful reproduction and better sound. When choosing an MP3,
weigh the advantage of a higher bitrate against the size of the file. 

Generally speaking, a bitrate of 128 kbps or higher will yield satisfactory
sound quality. 


160 Kbps
MP3s encoded at 160 Kbps have a 9:1 compression ratio. One minute of music
will equal approximately 1.5MB of disk space. For this setting, expect
CD-quality files. 


128 Kbps
MP3s encoded at 128 Kbps have an 11:1 compression ratio. One minute of music
will equal approximately 1MB of disk space. For this setting, expect
CD-quality 
files. 


96 Kbps
MP3s encoded at 96 Kbps have a 15:1 compression ratio. One minute of music
will equal approximately 700KB of disk space. For this setting, expect near
CD-quality files. 


64 Kbps
MP3s encoded at 64 Kbps have a 15:1 compression ratio. One minute of music
will equal approximately 400KB of disk space. For this setting, expect FM
radio-quality files.

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