Proc. SPIE. 7351, Mobile Multimedia/Image Processing, Security, and Applications 2009
KEYWORDS: Video, Ultraviolet radiation, Computer programming, Video surveillance, Video compression, Analog electronics, Standards development, Video coding, Scalable video coding, Image quality standards
The H.264 video compression standard, aka MPEG 4 Part 10 aka Advanced Video Coding (AVC) allows new flexibility
in the use of video in the battlefield. This standard necessitates encoder chips to effectively utilize the increased
capabilities. Such chips are designed to cover the full range of the standard with designers of individual products given
the capability of selecting the parameters that differentiate a broadcast system from a video conferencing system. The
SmartCapture commercial product and the Universal Video Stick (UVS) military versions are about the size of a thumb
drive with analog video input and USB (Universal Serial Bus) output and allow the user to select the parameters of
imaging to the. Thereby, allowing the user to select video bandwidth (and video quality) using four dimensions of
quality, on the fly, without stopping video transmission. The four dimensions are: 1) spatial, change from 720 pixel x
480 pixel to 320 pixel x 360 pixel to 160 pixel x 180 pixel, 2) temporal, change from 30 frames/ sec to 5 frames/sec, 3)
transform quality with a 5 to 1 range, 4) and Group of Pictures (GOP) that affects noise immunity. The host processor
simply wraps the H.264 network abstraction layer packets into the appropriate network packets. We also discuss the
recently adopted scalable amendment to H.264 that will allow limit RAVC at any point in the communication chain by
throwing away preselected packets.
Proc. SPIE. 7348, Modeling and Simulation for Military Operations IV
KEYWORDS: Signal to noise ratio, Unmanned aerial vehicles, Video, Personal digital assistants, Telecommunications, Modeling and simulation, Analog electronics, Data communications, Systems modeling, Video coding
Close Air Support (CAS) is the use of air power in close proximity to friendly forces against enemy combatants. CAS
requires precise and detailed communication between the personnel on the ground and the air vehicles. To be useful, a
network simulation should be a superposition on the planning simulations for these activities. In a CAS mission, all of
the above activities are critical. A hypothetical CAS mission is modeled as an "as is" solution with stove-piped
communications and a "to be" network enabled solution. A co-simulation laboratory using OPNET with SITL
(SYSTEM in the Loop, cosim, JFORCES (Joint Force Operational Readiness Combat Effectiveness Simulator), and
JSAF (Joint Semi-Automated Forces) simulation system is described.
Rate adaptivity is an important concept in data intensive applications such as video communications. In this paper, we
present an example rate adaptive, live, video communications system over IEEE 802.11 wireless networks, which
integrate channel estimation, rate adaptive video encoding, wireless transmission, reception, and playback. The video
stream over the wireless network conforms to the RTP payload format for H.264 video, and can be retrieved and
displayed by many popular players such as QuickTime and VLC. A live, video-friendly, packet-dispersion-based
algorithm will be used to estimate the available bandwidth, which is then used to trigger rate control to achieve rate
adaptive video coding on the fly.
In this paper, a wireless channel is viewed as a heterogeneous network in the time domain, and an adaptive video transmission scheme for H.264 scalable video over wireless channels modeled as a finite-state Markov chain processes is presented. In order to investigate the robustness of adaptive video transmission for H.264 scalable video over wireless channels, statistical channel models can be employed to characterize the error and loss behavior of the video transmission. Among various statistical channel models, a
finite-state Markov model has been considered as suitable for both wireless links as Rayleigh fading channels and wireless local area networks as a combination of bit errors and packet losses. The H.264 scalable video coding enables the rate adaptive source coding and the feedback of channel parameters facilitates the adaptive channel coding based on the dynamics of the channel behavior. As a result, we are able to develop a true adaptive joint source and channel based on instantaneous channel estimation feedback. Preliminary experimental results demonstrate that the estimation of the finite-state Markov channel can be quite accurate and the adaptive video transmission based on channel estimation is able to perform significantly better than the simple channel model in which only average bit error rate is used for joint source and channel coding design.
Rate control for video transmission becomes extremely important in "bandwidth-precious" scenarios and added real-time constraints such as joint source channel coding make it even more vital. Hence, there has always been a demand for simple and efficient rate control algorithms. The approximate linear relationship between coding rate (R) and percentage of zeros among the quantized spatial transform coefficients (ρ) is exploited in the present work, to cater to such low-bandwidth, low-delay applications. The current rate control algorithm for H.264 is used as the benchmark for comparison. The extensive experimental results show that ρ-Domain model outperforms the existing algorithm with a more robust rate control, besides yielding a similar or improved Peak Signal to Noise Ratio (PSNR) and being faster
We examine various issues related to demonstrating real-time channel adaptive video communications for UAVs using the latest-generation H.264 video compression technology. These issues include among others: real-time channel estimation techniques, real-time data rate adaptation techniques in H.264/AVC, latency in encoding, current encoding speeds, transcoding, and scalable video developments in H.264, all as essential steps along the way. These demonstrations will be conducted in a communication laboratory and a limited operational testing environment.
A method aimed at approximating the solution to differential equations with driving terms and whose solutions are non-stationary signals is described. The author has previously examined, using the approach of Galleani and Cohen the validity of the approximation method in phase space using the Wigner-distribution. He applied the method to second order differential equations and used for driving terms a variety of forcing functions that have smoothed and monotonically increasing phase functions. By examining the results, insight is gained into the nature of the solution and the associated dynamics of the system. This paper examines the approximation methods when the spectrogram is used, the spectrogram being the most widely used time-frequency distribution. The results show that the approximation scheme works very well for the spectrogram and in many cases works better than for the Wigner distribution.
Galleani and Cohen recently developed a Wigner-distribution based approach for the study of linear differential equations in general, and the gliding tone problem in particular. In this research, we extend these results by considering an exponential chirp and also a set of arbitrarily selected forcing functions. These forcing functions are taken from a class of smoothed and monotonically increasing phase functions. By examining a number of arbitrary selected forcing functions from this set, insight is gained into the nature of the solution and the associated dynamics of the system.