A novel unbalanced multiple description scheme for video transmission over WLAN

Abstract

Video communication over lossy packet networks such as the Internet or wireless links, is hampered by packet loss. Indeed, video quality severely degrades in presence of lost packets. This paper describes a technique based on Unbalanced Multiple Description Coding (UMD) to improve the robustness of video transmission. The proposed system relies on two descriptions, HR (High-Resolution) and LR (Low-Resolution) where LR description is primarily used as redundancy. HR and LR are produced by using different encoding parameters. The novelty of our approach, compared to other techniques based on UMD, is the use of different intra refresh periods for the produced descriptions. In particular we use shorter intra refresh period for LR description (in order to improve its resilience to bursts of packet losses), and higher intra refresh period for HR description (in order to improve coding efficiency). Moreover, a novel packetization scheme has been introduced in order to optimize network performance. This technique is able to produce acceptable quality even if redundancy percentage is less than packet loss rate. Therefore our UMD approach is suitable for multicast video distribution over WLAN (e.g. in "hotspots") where estimating packet loss can be a difficult task because different receivers experience different loss patterns.

Supporting Live Video on Ad Hoc Wireless Networks: Unbalanced Multiple Description Coding, Single Path Transport and Recursive Error Concealment

“…Moreover, coding and interleaving over a large number of packets may not satisfy the stringent delay constraint. [3] uses a lower IR period for the LR stream compared to the HR one. Although the solution preserves the efficiency of the HR stream, it does not effectively limit error propagation in the HR decoder.…”

“…To address the second problem, [3] recover a given macroblock lost in HR from the corresponding macroblock of the LR frame. It has block artifacts and does not consider the fact that errors propagate to succeeding inter-coded HR frames until a complete HR frame is coded in the intra-mode.…”

Optimized Rate Allocation for Unbalanced Multiple Description Video Coding Over Unreliable Packet Network

“…Particularly, for mobile ad hoc networks, what makes the multiple paths extremely difficult is the fact that there is no any guarantee on enough link resources. So UMDC over a single path is explored in [6]. Towards this end, since the LR description is used as the redundancy to relieve the effect of packet loss, a critical research question rises: how to effectively and efficiently allocate rates for HR and LR descriptions to achieve better visual quality according to the varied network conditions?…”

An Unbalanced Multiple Description Coding Scheme for Video Transmission Over Wireless Ad Hoc Networks

“…Particularly, for mobile ad hoc networks, what makes the multiple paths extremely difficult is the fact that there is no any guarantee on enough link resources. So UMDC over a single path is explored in [9]. Nevertheless, the simple LR-HR replacement policy adopted in [9] introduces the error-drift effect when any description encounters packet loss.…”

“…So UMDC over a single path is explored in [9]. Nevertheless, the simple LR-HR replacement policy adopted in [9] introduces the error-drift effect when any description encounters packet loss. Towards this end, we further improve our UMDC approach [6] to adapt to single path transmission (SPT).…”