tailieunhanh - Báo cáo nghiên cứu hóa học: Research Article Hybrid Modeling of Intra-DCT Coefficients for Real-Time Video Encoding

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Research Article Hybrid Modeling of Intra-DCT Coefficients for Real-Time Video Encoding | Hindawi Publishing Corporation EURASIP Journal on Image and Video Processing Volume 2008 Article ID 749172 13 pages doi 2008 749172 Research Article Hybrid Modeling of Intra-DCT Coefficients for Real-Time Video Encoding Jin Li Moncef Gabbouj and Jarmo Takala Faculty of Computing and Electrical Engineering Tampere University of Technology 33720 Tampere Finland Correspondence should be addressed to Jin Li Received 23 June 2008 Revised 25 September 2008 Accepted 2 December 2008 Recommended by James Fowler The two-dimensional discrete cosine transform 2-D DCT and its subsequent quantization are widely used in standard video encoders. However since most DCT coefficients become zeros after quantization a number of redundant computations are performed. This paper proposes a hybrid statistical model used to predict the zeroquantized DCT ZQDCT coefficients for intratransform and to achieve better real-time performance. First each pixel block at the input of DCT is decomposed into a series of mean values and a residual block. Subsequently a statistical model based on Gaussian distribution is used to predict the ZQDCT coefficients of the residual block. Then a sufficient condition under which each quantized coefficient becomes zero is derived from the mean values. Finally a hybrid model to speed up the DCT and quantization calculations is proposed. Experimental results show that the proposed model can reduce more redundant computations and achieve better real-time performance than the reference in the literature at the cost of negligible video quality degradation. Experiments also show that the proposed model significantly reduces multiplications for DCT and quantization. This is particularly suitable for processors in portable devices where multiplications consume more power than additions. Computational reduction implies longer battery lifetime and energy economy. Copyright 2008 Jin Li et al. This is an open access article distributed under the .