Constant Video Bit-Rate Control and Transcoding Strategies for MPEG Video Compression

• Main Authors: Kan, Kou-Sou, 甘果碩
• Other Authors: Kuo-Chin Fan
• Format: Others
• Language: zh-TW
• Published: 1997
• Online Access: http://ndltd.ncl.edu.tw/handle/13171818839239395414

博士 === 國立中央大學 === 資訊工程研究所 === 86 === Transmission of digital video via network has witnessed its popularity in current Internet applications. With the standardization of MPEG video coding, visual information transmission will no doubt play a major role in future Nation Information Infrastructure (NII). NII supports different applications, such as Digital-TV (DTV), Video-On-Demand (VOD), and High-Definition-Television (HDTV) over the inter-connected networks with different transmission characteristics including circuit switching and packet switching. Digital video transmission over the network requires strict timing synchronization between the server site and client site to guarantee real-time playback. Therefore, video coding based on an appropriate bit rate control is a key to the success of accommodating visual communication in NII environment. In this dissertation, two extremely efficient bit rate control algorithms are proposed for different applications: one is pseudo-constant bit rate video coder which is designed for source video compression, another is video transcoder which is designed for scaling the compressed MPEG-2 bit steam. The proposed technique, Adaptive Scene Analysis (ASA), is applied to source video bit rate control. ASA intelligently collects required information to obtain estimated bit count from the previous, present, and future frames. Combining with a series of dynamic rate control schemes, the ASA demonstrates impressive quality transition between successive frames. In addition, the bit rate irregularities caused by dramatic scene transition can be smoothed out in a very short period. The decoded picture quality is consistent among the successive frames. A comparison with the MPEG-2 Test Model 5 is also presented in this dissertation. An extremely efficient MPEG-2 video transcoding scheme, Low-Complexity and Low-Delay Video Transcoding (LCLD) is also proposed in this dissertation to freely adapt the bit rate of pre-compressed video into heterogeneous network constraints. The proposed strategy, LCLD, has low buffer requirement and results in low delay. Most importantly, the proposed method does not need the computational intensive motion estimation. Simulation results demonstrate that the proposed approach results in very consistent video quality and maintains the buffer level effectively. Comparing with direct decode/encode approach, the proposed scheme only suffers slight quality degradation. Experimental results demonstrate that the proposed approach can adapt the compressed video bit stream rate to the various network channel capacities.