Browsing by Author "Huang, Lin-Shung"

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A rate-distortion optimization model for SVC inter-layer encoding and bitstream extraction
(2008-12-01)
Peng, Wen-Hsiao
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Zao, John K.
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Huang, Hsueh-Ting
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Wang, Tse-Wei
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Huang, Lin-Shung
The Scalable Video Coding (SVC) standard enables viewing devices to adapt their video reception using bitstream extraction. Since SVC offers spatial, temporal, and quality combined scalability, extracting proper bitstreams for different viewing devices can be a non-trivial task, and naive choices usually produce poor playback quality. In this paper, we propose a two-prong approach to achieve rate-distortion (R-D) optimal extraction of SVC bitstreams. For SVC encoding, we developed a set of adaptation rules for setting the quantization parameters and the inter-layer dependencies among the SVC coding layers. A well-adapted SVC bitstream thus produced manifests good R-D trade-offs when its scalable layers are extracted along extraction paths consisting of successive refinement steps. For extracting R-D optimized bitstreams for different viewing devices, we formalized the notion of optimal and near-optimal extraction paths and devised computationally efficient strategies to search for the extraction paths. Experiment results demonstrated that our R-D optimized adaptation schemes and extraction strategies offer significant improvement in playback picture quality among heterogeneous viewing devices. Particularly, our adaptation rules promise R-D convexity along optimal extraction paths and permit the use of steepest-descent strategy to discover the optimal/near-optimal paths. This simple search strategy performs only half of the computation necessary for an exhaustive search. (C) 2008 Elsevier Inc. All rights reserved.
Rate-distortion optimized SVC bitstream extraction for heterogeneous devices : A preliminary investigation
(2007)
Peng, Wen-Hsiao
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Huang, Lin-Shung
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Zao, John K.
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Lu, Jiun-Shien
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Wang, Tse-Wei
The emerging SVC standard enables partial extraction and decoding of video bitstreams, and thus allows various viewing devices to adapt their video reception and playback according to devices capability and network performance. This desirable feature, however, comes with a caveat: the parts of a bitstream needed for providing good quality playback at different devices may differ significantly depending on the visual characteristics of video programs, the quantization and dependency settings of SVC encoders as well as the display formats of viewing devices. In this paper, we present the results of our preliminary investigation on the intricate relations among these factors. We discovered a set of constraints on the setting of quantization parameters and the choices of reference layers for inter-layer dependencies that ensures good rate-distortion trade-offs and regular bitstream; extraction paths. We called these constraints, the adaptation rules for inter-layer encoding, and their resulting outputs, the well-adapted layers/bitstreams. We further discovered that bitstream extraction by different viewing devices follow predictable paths if the SVC bitstream is well-adapted and the playback process extracts a complete set of interdependent network abstraction layer (NAL) units in every refinement step. These regular extraction paths enabled us to develop an efficient bitstream extraction algorithm based on local optimization of rate-distortion ratios. The experimental results using standard testing sequences confirmed our findings.
Trickle: Resilient real-time video multicasting for dynamic peers with limited or asymmetric network connectivity
(2006)
Guo, Yu-Hsuang
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Zao, John K.
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Peng, Wen-Hsiao
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Huang, Lin-Shung
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Kuo, Fang-Po
Some of the most challenging scenarios for peer-to-peer multimedia applications arise when the applications require real-time interactions among their users. In those cases, the expectation of sub-second responses prohibits the use of popular P2P IPTV software because those programs invariably use large video buffers to amortize the propagation delays of individual frames and thus cause notable and dispersed viewing latencies among their users. The performance of these programs degrade even further if the users are connected to home networks that offer narrow uplink channels or through wireless links that experience frequent throughput fluctuations. In order to overcome these shortcomings, we develop Trickle, a peer-to-peer real-time media streaming system that can transport H.264 video streams with low link stresses (less than 250Kb/s) and stable sub-second frame delays through the use of erasure correction codes along with the clever construction of multiple mullicast trees and the recruitment of many peer helpers. This paper presents the first fruits of our work including the principles and mechanisms of Trickle, its simulated performance based on H.264 video traces and its merit comparisons against SplitStream, the first application layer multicasting protocol for video streaming, and CoolStreansing, a news-making P2P IPTV program that works like BitTorrent.