(A) joint encoder and channel rate control based on DCT codewords counting for VBR MPEG video over ATM networks

Abstract

To prevent a buffer from overflowing or to comply with the traffic parameters negotiated with network, it is necessary for video encoder to have a bit rate control strategy to meet a target bit rate exactly. In this dissertation, we propose a look-ahead bit rate control algorithm to meet the bit budget exactly, which is to utilize the number of codewords calculated through a pre-analysis of DCT (discrete cosine transform) coefficients with a frame delay. Based on the rate control method, an improved bit rate allocation method is proposed for each picture type. It is shown that the proposed bit rate control algorithms are accurate and effective in encoder rate control. The characteristics of VBR (variable bit rate) MPEG video make it difficult to manage network resources. In the second part, we deal with the issues related to efficiently transmitting VBR MPEG video traffic over asynchronous transfer mode (ATM) networks, while maintaining consistent visual quality and improving network utilization in continuous and real-time applications. We propose a joint encoder and channel rate control scheme that comply with not only negotiated traffic parameters but also constraints imposed by encoder and decoder buffers. Then a dynamic bandwidth renegotiation method is proposed by combining the above scheme with a traffic smoothing method that can make the peak rate close to the sustainable rate. The efficiency of the proposed method is compared with other competitive schemes such as transmission methods for the unconstrained VBR and the constant bit rate (CBR) scheme with average bandwidth equal to that of the proposed methods.``