Miloš Radosavljević

Fast coding unit selection based on local texture characteristics for HEVC intra frame

High Efficiency Video Coding (HEVC) is a novel video compression standard. It provides significantly better performance than its predecessor, but introduces high computational complexity due its hierarchical block structure. Determining Coding Units (CU), Prediction Units (PU), and Transform Units (TU) size is a time consuming process, as block partitioning decisions are based on rate-distortion optimization (RDO). Taking into account all possible outcomes in terms of different block sizes and different prediction modes that HEVC can exploit, RDO is computationally very intense. To speed-up the block partitioning decisions we propose a novel approach for the CU size selection for intra frames based on local image characteristics. We use data from the source image itself to make decisions on whether to split CU or not. Split decisions are based on the histogram matching of the Local Binary Patterns on two consecutive CU depths. Results show that encoding time can be reduced compared to the HM16.2 reference software by bypassing RDO calculation for some specific CUs. Different performance-complexity configurations are investigated. Based on the proposed configuration, performance loss varies from almost negligible up to 0.87dB using BD-PSNR metric. However, speed-up is from 5.4% up to 80.2% on average.

QoE-aware Rate-Conservative dynamic HTTP streaming over mobile cellular networks

In this paper we investigate the design of DASH stream-switching solution suitable for mobile cellular video streaming consumers. Our goal is to design a solution that reduces the amount of downloaded content while adhering to user preferences regarding received video quality. We firstly present a graphical (trellis-like) representation of a stream-switching process, and then investigate different approaches to search for an optimal path through a “stream-switching graph” using suitably defined utility function. We target our search towards the path that will: i) respect underlying wireless-link rate limitations, ii) maintain segment selection that is efficient in terms of the quality vs the amount of the downloaded data, and iii) reduce disturbing quality variations. The simulation results demonstrate the performance of the proposed QoE-aware Rate-Conservative (QaRC) DASH as compared to the recently proposed baseline stream-switching solution.

High bit-depth image compression with application to seismic data

Inspired by the high performance of High Efficiency Video Coding (HEVC), this paper reports our work on applying the ideas of HEVC intra coding to compression of high-depth images such as 32 bits per pixel (b/p) seismic data. Compared to a licensed commercial wavelet-based codec that is currently used for seismic image compression, which performs on par with JPEG-XR, our new image codec significantly improves the PSNR vs. compression ratio performance. The codecs subject performance is rated by geologist as highly satisfactory.

Possibility of L-(+)-lactic acid fermentation using malting, brewing, and oil production by-products

Industrial by-products such as brewers spent grain (BSG) hydrolysate, malt rootlets extract (MRE) and soybean meal extract (SME) were used for L-(+) lactic acid (LA) production by a pure L. rhamnosus ATCC 7469 strain. The effect of the addition of MRE (10-50%) or SME (10-50%) in BSG hydrolysate on batch and fed-batch LA fermentation was evaluated. The addition of MRE and SME increased the concentration of free amino nitrogen (FAN) and essential minerals (Fe, Mg, Mn, and Zn), which had a positive effect on the fermentation. Also, the MRE addition significantly lowered C/N ration to a more favorable level for the efficient LA fermentation. In batch fermentation, the highest LA concentration (25.73 g/L), yield (86.31%), and volumetric productivity (0.95 g/L h-1), were obtained with the addition of 50% MRE. Further increase in LA concentration to 58.01 g/L, yield to 88.54%, and volumetric productivity to 1.19 g/L h-1 was achieved in fed-batch fermentation with addition of 50% MRE. A high optical purity of LA with 99.7% of L-(+)-isomer was obtained on the substrate based on industrial by-products. In addition, solid remains after BSG hydrolysis and MRE and SME preparation, together with the biomass of L. rhamnosus separated after the fermentation could be a good base for feed preparation.

Sugar beet pulp as a carrier for Lactobacillus paracasei in lactic acid fermentation of agro-industrial waste

Lactic acid (LA) has gained considerable importance in the global market due to a wide range of applications. Because of the growing demand for food and feed, the use of lignocellulosic residues, by-products and waste streams is highly needed for commercial LA production. This study investigated the possibility of using potato stillage and sugar beet molasses for LA and biomass production by Lactobacillus paracasei NRRL B-4564 immobilized on sugar beet pulp. Adsorption of L. paracasei enabled easy separation of bacterial biomass from the fermentation media and its efficient reuse in three successive batch cycles. Total LA concentration of 146 g L and average productivity of 1.03 g L h were achieved on waste substrate using bacterial cells immobilized on a natural carrier without mineral and nitrogen supplementation. The solid part of fermentation media remaining after LA fermentation is a valuable co-product, which could be used as animal feed rich in probiotic biomass.