Forward Adaptive Laplacian Source Coding Based on Restricted Quantization

Bojan Denic, Zoran Peric, Vladimir Despotovic, Nikola Vucic
2018 Information Technology and Control  
A novel solution for Laplacian source coding based on the three-level restricted quantization is proposed in this paper. The restricted quantization provides the reduction of granular distortion with the proper choice of the support region. We use the combination of two three-level restricted quantizers having unequal support regions, which are selected based on the lower distortion. The quantizers are designed using the Lloyd-Max's algorithm, by assuming the restricted Laplacian distribution
more » ... cian distribution of the input signal. The outputs are encoded using the Huffman code. In order to improve the performance the forward adaptive algorithm was employed, where the adaptation to the signal variance (power) was performed on frame-by-frame basis. Theoretical analysis has shown that in this manner the robustness and adaptability of the proposed solution is enabled. The experimental results prove that the proposed switched three-level restricted quantizer is superior in comparison to the three-level unrestricted quantizer, and outperforms the one-bit (two-level) Lloyd-Max's quantizer, while offering performance comparable to the two-bit (four-level) Lloyd-Max's baseline with large savings in bit rate. KEYWORDS: Restricted scalar quantization, switched quantization, Lloyd-Max's algorithm, Huffman code, forward adaptation. Information Technology and Control 2018/2/47 210 Information Technology and Control 2018/2/47 solutions in [16] and [18] where the authors want to achieve the maximization in the signal quality, the proposed solution offers high data compression. The performances of the proposed codec are evaluated using the Signal to Quantization Noise Ratio (SQNR) and bit rate. The effectiveness of the proposed algorithm has been proven theoretically and experimentally. The experimental results are compared with the baselines including three-level unrestricted quantization, one-bit and two-bit Lloyd-Max quantization [4, 10, 11, 20] . The reminder of the paper is organized as follows: in Section 2 we present a detailed description of design of the restricted three-level quantizer and the switched quantizer with the forward adaptive coding scheme. In Section 3 we present and discuss the experimental results and finally we give concluding remarks in Section 4.
doi:10.5755/j01.itc.47.2.16670 fatcat:5sw6rdyrhzegtcyieyfcrz4v74