Đang chuẩn bị liên kết để tải về tài liệu:
Image and Videl Comoression P17

This chapter introduces ITU-T video coding standards H.261 and H.263, which are established mainly for videophony and videoconferencing. The basic technical detail of H.261 is presented. The technical improvements with which H.263 achieves high coding efficiency are discussed. Features of H.263+, H.263++, and H.26L are presented. 19.1 INTRODUCTION Very low bit rate video coding has found many industry applications such as wireless and network communications. The rapid convergence of standardization of digital video-coding standards is the reflection of several factors: the maturity of technologies in terms of algorithmic performance, hardware implementation with VLSI technology, and the market need for rapid advances in. | 1Q ITU-T Video Coding Standards H.261 and H.263 This chapter introduces ITU-T video coding standards H.261 and H.263 which are established mainly for videophony and videoconferencing. The basic technical detail of H.261 is presented. The technical improvements with which H.263 achieves high coding efficiency are discussed. Features of H.263 H.263 and H.26L are presented. 19.1 INTRODUCTION Very low bit rate video coding has found many industry applications such as wireless and network communications. The rapid convergence of standardization of digital video-coding standards is the reflection of several factors the maturity of technologies in terms of algorithmic performance hardware implementation with VLSI technology and the market need for rapid advances in wireless and network communications. As stated in the previous chapters these standards include JPEG for still image coding and MPEG-1 2 for CD-ROM storage and digital television applications. In parallel with the ISO IEC development of the MPEG-1 2 standards the ITU-T has developed H.261 ITU-T 1993 for videotelephony and videoconferencing applications in an ISDN environment. 19.2 H.261 VIDEO-CODING STANDARD The H.261 video-coding standard was developed by ITU-T study group XV during 1988 to 1993. It was adopted in 1990 and the final revision approved in 1993. This is also referred to as the P x 64 standard because it encodes the digital video signals at the bit rates of P x 64 Kbps where P is an integer from 1 to 30 i.e. at the bit rates 64 Kbps to 1.92 Mbps. 19.2.1 Overview of H.261 Video-Coding Standard The H.261 video-coding standard has many features in common with the MPEG-1 video-coding standard. However since they target different applications there exist many differences between the two standards such as data rates picture quality end-to-end delay and others. Before indicating the differences between the two coding standards we describe the major similarity between H.261 and MPEG-1 2. First both .