Variable Bitrate - Nokia N91 User Manual

of AAC, such as AAC+ and enhanced AAC+ (eAAC+)
provide CD quality audio at bitrates as low as 48 Kbps.
Classical music and music with nuances usually require a
higher bitrate than basic pop music.
For speech or other sources where the quality of the sound
is less important than saving storage space, you can use
bitrates between 8 and 64 Kbps. At low bitrates WMA or
AAC generally gives better results than MP3.

Variable bitrate

Your device also supports variable bitrate (VBR). Variable
bitrate means that the bit rate of the encoding varies with
the complexity of the encoded material. When using VBR,
the encoding is optimized to preserve a constant audio
quality throughout the track, rather than losing quality
for complex music sections as with constant bitrate (CBR)
encoding.
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