Institute for Systems Research
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Item 3D Wavelet-Based Video Codec with Human Perceptual Model(1999) Gu, Junfeng; Baras, John S.; ISR; CSHCNThis thesis explores the use of a human perceptual model in video compression, channel coding, error concealment and subjective image quality measurement.The perceptual distortion model just-noticeable-distortion (JND) is investigated. A video encoding/decoding scheme based on 3D wavelet decomposition and the human perceptual model is implemented. It provides a prior compression quality control which is distinct from the conventional video coding system. JND is applied in quantizer design to improve the subjective quality ofcompressed video.
The 3D wavelet decomposition helps to remove spatial and temporal redundancy and provides scalability of video quality. In order to conceal the errors that may occur under bad wireless channel conditions, a slicing method and a joint source channel coding scenario that combines RCPC with CRC and uses the distortion information toallocate convolutional coding rates are proposed. A new subjective quality index based on JND is proposed and used to evaluate the overall performance at different signal to noise ratios (SNR) and at different compression ratios.
Due to the wide use of arithmetic coding (AC) in data compression, we consider it as a readily available unit in the video codec system for broadcasting. A new scheme for conditional access (CA) sub-system is designed based on the cryptographic property of arithmetic coding. Itsperformance is analyzed along with its application in a multi-resolution video compression system. This scheme simplifies the conditional access sub-system and provides satisfactory system reliability.
Item A Video Transmission System Based on a Human Visual Model(1999) Jiang, Yimin; Gu, Junfeng; Baras, John S.; Baras, John S.; ISR; CSHCNThis paper presents a joint source-channel coding scheme of digital video broadcasting over satellite channels. The video compression is based on a human visual model. A perceptual distortion model, the just-noticeable-distortion (JND), is applied to improve the subjective quality of compressed videos.3-D wavelet decomposition can remove spatial and temporal redundancy and provide scalability of video quality. In order to conceal the errors occurring under bad channel conditions, a novel slicing method and a joint source channel coding scenario that combines RCPC with CRC and utilizes the distortion information to allocate convolutional coding rates are presented. A new performance index based on JND is proposed and used to evaluate the overall performance at different signal-to-noise ratios (SNR). Our system uses the OQPSK modulation scheme.
VTC 1999
Item A Video Transmission System Based on Human Visual Model for Satellite Channel(1999) Gu, Junfeng; Jiang, Yimin; Baras, John S.; ISR; CSHCNThis paper presents a practical architecture for joint source-channel coding of human visual model-based video transmission over satellite channel. Perceptual distortion model just-noticeable-distortion (JND) is applied to improve the subjective quality of compressed videos. 3-D wavelet decomposition can remove spatial and temporal redundancy and provide scalability of video quality.In order to conceal errors occurring under bad channel conditions, a novel slicing method and a joint source channel coding scenario that combines RCPC with CRC and utilizes the distortion information to allocate convolutional coding rates are proposed. A new performance index based on JND is proposed and used to evaluate the overall performance at different signal-to-noise ratios (SNR). Our system uses OQPSK modulation scheme.
This paper has been submitted to Globecomm99, Rio de Janeiro, Brazil, December 5-9, 1999.
Item A Practical Transmission System Based on the Human Visual Model for Satellite Channels(1999) Gu, Junfeng; Jiang, Yimin; Baras, John S.; Baras, John S.; ISR; CSHCNThis paper presents a practical architecture for joint source-channel coding of human visual model-based video transmission over a satellite channel. Perceptual distortion model just-noticeable-distortion (JND) is applied to improve the subjective quality of compressed videos. 3-D wavelet decomposition can remove spatial and temporal redundancy and provide the scalability of video quality.In order to conceal errors occurring under bad channel conditions, a novel slicing method and a joint source channel coding scenario that combines RCPC with CRC and utilizes the distortion information to allocate convolutional coding rates are proposed. A new performance index based on JND is proposed and used to evaluate the overall performance at different signal-to-noise ratios (SNR). Our system uses OQPSK modulation scheme.
The research and scientific content in this material has been submitted to Globecom'99. Item A Generalized Gilbert-Varshamov Bound Derived via Analysis of a Code-Search Algorithm(1992) Gu, Junfeng; Fuja, Tom E.; ISRThis correspondence derives a generalization of the Gilbert- Varshamov bound that is applicable to block codes whose codewords must be drawn from irregular sets; the bound improves by a factor of four a similar result recently published by Kolesnik and Krachkovsky. It is derived by analyzing a code search algorithm we refer to as the "Altruistic Algorithm". This algorithm iteratively deletes potential codewords so that at each iteration the "worst" candidate is removed; the bound is derived by demonstrating that, as the algorithm proceeds, the average volume of a sphere of a given radius approaches the maximum such volume and so a bound previously expressed in terms of the maximum volume can in fact be expressed in terms of the average volume. Examples of applications where the bound is relevant include error-correcting (d, k)- constrained codes and binary codes for code division multiple access.