3D video coding and transmission

The capture, transmission, and display of 3D content has gained a lot of attention in the last few years. 3D multimedia content is no longer con fined to cinema theatres but is being transmitted using stereoscopic video over satellite, shared on Blu-RayTMdisks, or sent over Internet technologies. Stereoscopic displays are needed at the receiving end and the viewer needs to wear special glasses to present the two versions of the video to the human vision system that then generates the 3D illusion. To be more e ffective and improve the immersive experience, more views are acquired from a larger number of cameras and presented on di fferent displays, such as autostereoscopic and light field displays. These multiple views, combined with depth data, also allow enhanced user experiences and new forms of interaction with the 3D content from virtual viewpoints. This type of audiovisual information is represented by a huge amount of data that needs to be compressed and transmitted over bandwidth-limited channels. Part of the COST Action IC1105 \3D Content Creation, Coding and Transmission over Future Media Networks" (3DConTourNet) focuses on this research challenge.peer-reviewe

Bank credit and economic activity

Bank loans ; Vector autoregression ; Supply and demand ; Monetary policy - United States

Plans for the development of cryogenic engines for space exploration

The NASA Lewis Research Center (LeRC) is conducting a broad range of basic research and focused technology development activities in both aeronautical and space propulsion. By virtue of the successful conduct of these programs, LeRC is strongly qualified to lead Advanced Development and subsequent development programs on cryogenic space propulsion systems on support of the Space Exploration Initiative. A review is provided of technology status, including recent progress in the ongoing activities, and a top level description of the proposed program

BIOPHYSICAL SIMULATION IN SUPPORT OF CROP PRODUCTION DECISIONS: A CASE STUDY IN THE BLACKLANDS REGION OF TEXAS

Economic feasibility of Texas Blacklands corn production in relation to sorghum, wheat, and cotton is studied. Biophysical simulation generated yield data are integrated with an economic decision model using quadratic programming. Given the various scenarios analyzed, corn is economically feasible for the Blacklands. A crop mix of half corn and half cotton production is selected under risk neutrality with wheat entering if risk aversion is present. Corn and grain sorghum production are highly substitutable. Profit effects attributed to changing corn planting dates are more pronounced than profit changes resulting from altering corn population or maturity class.Crop Production/Industries,

The Zero-Lift Drag of Several Configurations of the XAAM-N-2 Pilotless Aircraft. TED No. NACA DE332

Free-flight tests have been made to determine the zero-lift drag of several configurations of the XAAM-N-2 pilotless aircraft. Base-pressure measurements were also obtained for some of the configurations. The results show that increasing the wing-thickness ratio from 4 to 6 percent increased the wing drag by about 100 percent at M = 1.3 and by about 30 percent at M = 1.8. Increasing the nose fineness ratio from 5.00 to 6.25 reduced the drag coefficient of the wingless models a maximum of about 0.030 (10 percent) at M = 2.0. A corresponding change in nose shape for the winged models decreased the drag coefficient by about 0.05 in the Mach number range from 1.1 to 1.4; at Mach numbers greater than 1.6 no measurable reduction in drag coefficient was obtained. The drag of the present Sparrow fuselage is less than that of a parabolic fuselage which could contain the same equipment

A robust error detection mechanism for H.264/AVC coded video sequences based on support vector machines

Current trends in wireless communications provide fast and location-independent access to multimedia services. Due to its high compression efficiency, H.264/AVC is expected to become the dominant underlying technology in the delivery of future wireless video applications. The error resilient mechanisms adopted by this standard alleviate the problem of spatio-temporal propagation of visual artifacts caused by transmission errors by dropping and concealing all macroblocks (MBs) contained within corrupted segments, including uncorrupted MBs. Concealing these uncorrupted MBs generally causes a reduction in quality of the reconstructed video sequence.peer-reviewe

A hybrid error control and artifact detection mechanism for robust decoding of H.264/AVC video sequences

This letter presents a hybrid error control and artifact detection (HECAD) mechanism which can be used to enhance the error resilient capabilities of the standard H.264/advanced video coding (AVC) codec. The proposed solution first exploits the residual source redundancy to recover the most likelihood H.264/AVC bitstream. If error recovery is unsuccessful, the residual corrupted slices are then passed through a pixel-level artifact detection mechanism to detect the visually impaired macroblocks to be concealed. The proposed HECAD algorithm achieves overall peak signal-to-noise ratio gains between 0.4 dB and 4.5 dB relative to the standard with no additional bandwidth requirement. The cost of this solution translates in a marginal increase in the complexity of the decoder. In addition, this method can be applied in conjunction with other error resilient strategies and scales well with different encoding configurations.peer-reviewe

A support vector machine approach for detection and localization of transmission errors within standard H.263++ decoders

Wireless multimedia services are increasingly becoming popular boosting the need for better quality-of-experience (QoE) with minimal costs. The standard codecs employed by these systems remove spatio-temporal redundancies to minimize the bandwidth required. However, this increases the exposure of the system to transmission errors, thus presenting a significant degradation in perceptual quality of the reconstructed video sequences. A number of mechanisms were investigated in the past to make these codecs more robust against transmission errors. Nevertheless, these techniques achieved little success, forcing the transmission to be held at lower bit-error rates (BERs) to guarantee acceptable quality. This paper presents a novel solution to this problem based on the error detection capabilities of the transport protocols to identify potentially corrupted group-of-blocks (GOBs). The algorithm uses a support vector machine (SVM) at its core to localize visually impaired macroblocks (MBs) that require concealment within these GOBs. Hence, this method drastically reduces the region to be concealed compared to state-of-the-art error resilient strategies which assume a packet loss scenario. Testing on a standard H.263++ codec confirms that a significant gain in quality is achieved with error detection rates of 97.8% and peak signal-to-noise ratio (PSNR) gains of up to 5.33 dB. Moreover, most of the undetected errors provide minimal visual artifacts and are thus of little influence to the perceived quality of the reconstructed sequences.peer-reviewe

Robust decoder-based error control strategy for recovery of H.264/AVC video content

Real-time wireless conversational and broadcasting multimedia applications offer particular transmission challenges as reliable content delivery cannot be guaranteed. The undelivered and erroneous content causes significant degradation in quality of experience. The H.264/AVC standard includes several error resilient tools to mitigate this effect on video quality. However, the methods implemented by the standard are based on a packet-loss scenario, where corrupted slices are dropped and the lost information concealed. Partially damaged slices still contain valuable information that can be used to enhance the quality of the recovered video. This study presents a novel error recovery solution that relies on a joint source-channel decoder to recover only feasible slices. A major advantage of this decoder-based strategy is that it grants additional robustness while keeping the same transmission data rate. Simulation results show that the proposed approach manages to completely recover 30.79% of the corrupted slices. This provides frame-by-frame peak signal-to-noise ratio (PSNR) gains of up to 18.1%dB, a result which, to the knowledge of the authors, is superior to all other joint source-channel decoding methods found in literature. Furthermore, this error resilient strategy can be combined with other error resilient tools adopted by the standard to enhance their performance.peer-reviewe

Accurate modelling of Ka-band videoconferencing systems based on the quality of experience

This work formed part of the project TWISTER, which was financially supported under the European Union 6th Framework Programme (FP6). The authors are solely responsible for the contents of the paper, which does not represent the opinion of the European Commission.Ka-band satellite multimedia communication networks play important roles because of their capability to provide the required bandwidth in remote places of the globe. However, because of design complexity, in practice they suffer from poor design and performance degradation because of being practically forced to guarantee acceptable end-user satisfaction in conditions of extremely low bit error rates, which is emphasised with the vulnerability of compressed video content to transmission errors, often impossible to be applied during the service development phase. A novel discrete event simulation model is presented, which provides performance estimation for such systems based on subjective measurement and a better quality of experience. The authors show that the proposed model reduces implementation cost and is flexible to be used for different network topologies around the globe.peer-reviewe