Sanjeev Mehrotra, Wei-ge Chen, Kazuhito Koishida, and Naveen Thumpudi
Audio coding at low bitrates typically suffers from artifacts
caused by bandwidth truncation.
In this paper we present a novel scheme to code audio signals at low
bitrates which uses a traditional scalar quantization followed by
entropy coding to code some portions of the spectrum (typically the lower
The other portions (typically the higher portions)
of the spectrum are coded at a low bitrate
using an adaptive gain
shape vector quantizer where the codebook for vector quantization
is formed by unmodified or
modified versions of the portions of the spectrum which have already
Fixed pre-trained codebooks are also available for use in certain
The use of such a scheme results in an audio codec which has been
shown to be among the best audio codecs available at low bitrates.
In addition, the decoder complexity of this audio codec is significantly lower
than any other codec of equal quality at low bitrates.
In Proc. Workshop on Multimedia Signal Processing
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