Affiliations: Faculty of Electrical Engineering, University of
Niš, Aleksandra Medvedeva 14, 18000 Niš, Serbia.
E-mails: [email protected]; [email protected] | Faculty of Science and Mathematics, University of
Niš, Višegradska 33, 18000 Niš, Serbia. E-mail: [email protected]
Abstract: In this paper a new model for compression of Laplacian source is
given. This model consists of hybrid quantizer whose output levels are coded
with Golomb-Rice code. Hybrid quantizer is combination of uniform and
nonuniform quantizer, and it can be considered as generalized quantizer, whose
special cases are uniform and nonuniformquantizers. We propose new generalized
optimal compression function for companding quantizers. Hybrid quantizer has
better performances (smaller bit-rate and complexity for the same quality) than
both uniform and nonuniformquantizers, because it joins their good
characteristics. Also, hybrid quantizer allows great flexibility, because there
are many combinations of number of levels in uniform part and in
nonuniformpart, which give similar quality. Each of these combinations has
different bit-rate and complexity, so we have freedom to choose combination
which is the most appropriate for our application, in regard to quality,
bit-rate and complexity. We do not have such freedom of choice when we use
uniform or nonuniform quantizers. Until now, it has been thought that uniform
quantizer is the most appropriate to use with lossless code, but in this paper
we show that combination of hybrid quantizer and lossless code gives better
performances. As lossless code we use Golomb-Rice code because it is especially
suitable for Laplacian source since it gives average bit-rate very close to the
entropy and it is easier for implementation than Huffman code. Golomb-Rice code
is used in many modern compression standards. Our model can be used for
compression of all signals with Laplacian distribution.
