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This paper addresses the problem of how to efficiently manage the power consumption while preserving high visual quality performance in video coding for pervasive video applications. We define an optimization problem that corresponds to the minimization of both the power consumption and video distortion of a video encoder. A joint rate-complexity-distortion(R-C-D) model is developed to capture and control the general R-C-D behavior of video coding. Based on the analysis of the proposed model, optimization strategies are developed to achieve good video quality while maximizing the battery service life. We demonstrate how the observations and optimization strategies can be utilized in a practical parameterized encoder under various preferences of quality and power. We perform simulations on an instruction set simulator to exhibit the effectiveness of the proposed scheme.

A novel sulfonated diamine, 1,2-dihydro-2-(3-sulfonic-4-aminophenyl)-4-[4-(3-sulfonic-4-aminophenoxy)-phenyl]-phthalazin-1-one(S-DHPZDA), was successfully synthesized and two series of six-membered sulfonated polyimides (SPIs) were prepared from 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA), S-DHPZDA, and nonsulfonated diamines DHPZDA or 4,4′-diaminodiphenyl ether (ODA). The chemical structure of the S-DHPZDA and the SPIs were characterized by 1H NMR and FT-IR. Tough, brownish and transparent membranes were cast from SPIs’ solution in NMP. The water uptake, swelling ratio, chemical and thermal stability, hydrolytic and oxidative stability as well as proton conductivity of these new polymers were investigated systematically. Compared with Nafions, the obtained SPI membranes have onset decomposed temperatures of these two series SPIs were above 318 °C and decomposed temperature of main chain were 565 °C and excellent dimension stabilities on similar IECs. Introduction of phthalazinone moieties had improved the copolyimides’ solubility in polar aprotic organic solvents like m-cresol, NMP, DMSO, DMF etc. The SPIs had high proton conductivity (σ) in the order of magnitude of 10−3 to 10−2 S cm−1 depending on the degree of sulfonation (DS) of the polymers.

In this work, sulfonated poly(phthalazinone ether)s (SPPENK, SPPESK and SPPBEK) were synthesized by direct aromatic nucleophilic polycondensation reaction. H-bonded composite membranes were prepared from SPPENK, SPPESK and SPPBEK, respectively, and polyetherimide (PEI). Both of compounds were dissolved in N-methylpyrrolidone (NMP), and tough membranes were obtained by casting from NMP solution with 9:1 mass ratio of sulfonated poly(phthalazinone ether)s/PEI. These H-bonded composite membranes all showed better thermal, oxidative and mechanical stabilities than corresponding pure sulfonated polymers membranes. The H-bonded composite membranes had high proton conductive ranging from 0.02 to 0.06 S/cm at 95 °C. All membranes showed an increase in proton conductivities with temperature elevation. The swelling ratio of H-bonded composite membranes was lower than that of pure membranes.

To provide basic video services and applications in 3G wireless networks, two video coding formats, H.263 baseline and MPEG-4 visual simple profile, are commonly adopted in different forms for various usage scenarios. To ensure interoperability between these cases, we propose efficient compressed domain algorithms for transcoding between MPEG-4 visual simple profile and H.263 baseline, and among MPEG-4 visual simple profile coding modes. Experimental results show that our suggested algorithms provide significant complexity reduction and quality improvement, in terms of PSNR, compared to the spatial domain approach. Being the first complete work on transcoding between all kinds of MPEG-4 visual simple profile and H.263 baseline bit streams, we believe this work provides valuable solutions for various 3GPP (3rd generation partnership project) compliant video services and applications).

Mobile devices performing video coding and streaming over wireless and pervasive communication networks are limited in energy supply. To prolong the operational lifetime of these devices, an embedded video encoding system should be able to adjust its computational complexity and energy consumption as demanded by the situation and its environment. To analyze, control, and optimize the rate-distortion (R-D) behavior of the wireless video communication system under the energy constraint, we develop a power-rate-distortion (P-R-D) analysis framework, which extends the traditional R-D analysis by including another dimension, the power consumption. Specifically, in this paper, we analyze the encoding mechanism of typical video coding systems, and develop a parametric video encoding architecture which is fully scalable in computational complexity. Using dynamic voltage scaling (DVS), an energy consumption management technology recently developed in CMOS circuits design, the complexity scalability can be translated into the energy consumption scalability of the video encoder. We investigate the R-D behavior of the complexity control parameters and establish an analytic P-R-D model. Both theoretically and experimentally, we show that, using this P-R-D model, the video coding system is able to automatically adjust its complexity control parameters to match the available energy supply of the mobile device while maximizing the picture quality. The P-R-D model provides a theoretical guideline for system design and performance optimization in mobile video communication under energy constraints.

In wireless communication networks, an important issue that must be addressed is the limited energy supply of a mobile device, especially in wireless video applications. In this paper, we develop a parametric video encoding architecture, which is fully scalable in power consumption, and establish the power-rate-distortion (P-R-D) model of the video encoding system. Both theoretically and experimentally, we show that by using this P-R-D model, the encoding system is able to automatically adjust its complexity control parameters to match the available energy supply of the mobile device while maximizing the picture quality. The P-R-D model provides a theoretical guideline for system design and performance optimization in wireless video communication under power constraint.