Multibit decoding/encoding of binary codes using memory based architectures

IEEE Trans. Circuits Syst. II

1999

Variable-length code (VLC) is the most popular data-compression technique which has been used in many datacompression standards, such as JPEG, MPEG-2, and H.263. In this paper, we present a new memory-based tree-search algorithm and very large scale integration architecture for VLC decoders which can achieve very high decoding throughput performance. Different coding tables can be implemented by simply changing the contents of the memory without changing the system hardware. The coding table is mapped onto a memory whose space requirement has been minimized by using a new tree data structure and efficient memory-mapping strategy. In addition, we break the recursive dependency of iterative searching operations by predicting method. The proposed algorithm and architecture can predict the searching node and perform parallel operations. As a result, the decoding throughput rate can be enhanced to about three to eight times more than previously announced architecture. The proposed architecture mainly consists of memory modules and simple arithmetic unit. Based on 0.6-m single poly triple metal CMOS technology and MPEG-2 VLC table-15, the decoder system achieves average decoding throughput rate of 720 Mbits/s at 3 V and a 100-MHz clock rate.

Section: A Generalized Prediction Methods For Modifiedmentioning

confidence: 99%

Section: A Tree-based Code and Tree Structurementioning

confidence: 99%

A generalized prediction method for modified memory-based high throughput VLC decoder design

IEEE Trans. Circuits Syst. II

1999

“…Because their architectures are the direct mapping of coding tables, the VLSI implementations have to be redesigned when the tables are changed. Besides, the designs in [3] and [4] use the concurrent and parallel architectures to break the bottleneck of the decoding throughput. Nevertheless, they are designed for multiple independent bit streams.…”

Section: Introductionmentioning

confidence: 99%

A high-throughput memory-based VLC decoder with codeword boundary prediction

IEEE Trans. Circuits Syst. Video Technol.

Lee²,

Lee³

2000

Abstract-In this paper, we present a high-throughput memorybased VLC decoder with codeword boundary prediction. The required information for prediction is added to the proposed branch models. Based on an efficient scheme, these branch models and the Huffman tree structure are mapped onto memory modules. Taking the prediction information, the decompression scheme can determine the codeword length before the decoding procedure is completed. Therefore, a parallel-processor architecture can be applied to the VLC decoder to enhance the system performance. With a clock rate of 100 MHz, a dual-processor decoding process can achieve decompression rate up to 72.5 Msymbols/s on the average. Consequently, the proposed VLC decompression scheme meets the requirements of current and advanced multimedia applications.

A new approach of group-based VLC codec system with full table programmability

Lee²,

IEEE Trans. Circuits Syst. Video Technol.

2001

In this paper, the algorithm of a VLC codec system with new group-based approach is presented. Based on the proposed codeword grouping and symbol memory mapping, the groupsearching scheme and codec processes are completed by applying numerical properties and arithmetic operations to codewords and symbol addresses. The memory requirement of encoder is reduced by a novel symbol-converting scheme. Therefore, the programmable coding table and symbol representation can be achieved. Based on MPEG-like systems, an architecture design that performs concurrent VLC codec processes with constant symbol rate is presented. Simulation results show IOOMsps with 100MHz-clock for both encodingldecoding procedures can be achieved. As a result, it is suitable for those applications that require codec processes simultaneously, such as videoconferencing, and high throughput systems, such as HDTV. IntroductionRecently, progressive applications, such as HDTV, videoconferencing and user-defined coding table system, make challenges to VLC codec technology. The compressed bit stream of HDTV system is more than IOOMbps since the sampling rate is about 52Mpixelhec and the color profile is 4:2:2. Subsequently, the throughput requirement of VLC codec operation is increased several order of magnitudes than earlier applications. In contrast, the bit rate is much lower for videoconferencing which is established on the limited network bandwidth. However, the 2-way communication needs real time concurrent encodingldecoding procedures. To meet diverse applications and different data types, user-defined coding tables that are generated by precise symbol probability are essential to hrther increase compression ratio. Because the table information has to be loaded before the codec processes, the VLC codec systems require the programmability to change coding table without redesign.Both tree-searching and group-based algorithms for VLC codec system have been discussed. By representing coding To satisfy the mentioned application, the motivation behind our research is to develop a programmable coding table, low memory requirement, and high throughput VLC codec system. A new group-based VLC codec algorithm which take the advantage of numerical property of codeword and symbol address are presented. The operation throughput is improved significantly. With memory-based architecture, coding tables and symbol representations can be programmed. The organization of this paper is as follows. In section 2, the group-based VLC encodingldecoding algorithm is described. The symbolconverting scheme is presented, too. In section 3, the VLC codec architecture and performance estimation is discussed. Finally, concluding remarks are made in section 4.