Run-time allocation of buffer resources for maximizing video clip quality in a wireless last-hop system

摘要

The transmission of digital video over wireless channels faces many problems common Io both wired and wireless networks such as bandwidth and buffer restrictions and low energy constraints, together with problems unique to wireless technologies such as extreme and rapidly varying channel noise. In this paper, we focus on enabling (he wireless communication of video clips despite the noisy and dynamic nature of wireless channels. Many efforts have been made in the past to increase the error resiliency of compressed video, but these approaches have not considered the effects of buffering on the received video quality. Traditional buffering (where a "sliding window" of the next few frames is kept in the buffer at all times), while useful for overcoming latency jitter, cannot be used Io guarantee against poor video quality and stalls due to wireless channel fluctuations. To help overcome the weaknesses of traditional buffering, we introduced out-of-order buffering (ORBit), a method for selecting important frames from throughout a video clip and buffering them before playback begins. ORBit can lead to significant gains in video quality despite variations in the wireless channel during the communication of a video clip, but requires the judicious selection of ORBit frames, with their corresponding quantization and channel coding levels. To enable run-time selection of ORBit frames, we introduce a fast video distortion estimation technique. Using our estimation technique, we present an ORBiI decision algorithm that selects ORBit frames depending on the wireless technology and end-user appliance constraints. Using the ORBit has to wait for a few seconds before the video display begins. During decision algorithm, significant gains of up to 9 dB in video quality are obtained.