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“Rate Control for Video Transmission Over Variable Rate Channels”
by Chi-Yuan Wu
August 1998
Video has become a component of modern communications and multimedia applications. Communication networks and channels with very different characteristics, such as circuit-switched networks, packet-switched networks, Internet, ATM-based B-ISDN, and wireless channels, have been explored as the platform for video transmission. However, the underlying networks and channels place different constraints on the transport of video data. To comply with these constraints, it is necessary to implement rate control at the video encoder in video transmission applications. In this research, the problem of video rate control is studied by considering the constraining factors in a video transmission system (including the applicable end-to-end delay, channel throughput, and possible transmission errors) and translating these constraints into the encoding rate. The encoding rate constraints have to be observed by the encoder in order to guarantee the successful decoding and displaying of the video data that are streaming into the decoder. Based on this formulation of the rate control problem, a number of rate control algorithms, aim to maximize the video quality that are transmitted to the decoder, are proposed for video transmission over various types of transmission channels. The first communication channel under study for video transmission is a Variable Bit Rate (VBR) network with usage parameter control. A rate control approach is proposed to jointly select the source and channel rates in such VBR transmission environment. Another transmission environment under study for video transmission is burst-error channels. An integrated rate control and error control scheme is proposed such that the source encoding rate can be adaptive to the current channel condition. Overall performance of the video transmission, in terms of reconstructed video quality and data loss rate, can be improved.