Real-time Digital Video Research Articles

Design of an MPEG-2 codec

We review the design of a single-chip MPEG-2 a/v codec, covering the design process from the MPEG specifications and system requirements to the final design. After a brief overview of MPEG-1 and MPEG-2 standards, we examine the system requirements using as an example a universal serial bus (USB)-based MPEG-2 real-time digital video recorder. Finally, we present in more detail the hardware and software architecture of a specific MPEG a/v codec.

Channel coding and signal processing for optical recording systems beyond DVD

High-capacity optical recording beyond DVD is physically made possible by using blue lasers with shorter wavelengths, and improved lenses with high numerical aperture. In collaboration with Sony, a new optical disc format for a real-time Digital Video Recording system (DVR) has been developed. Signal processing plays a key role in the optimization of disc capacity together with system margins of the optical drive. For the new format, new modulation codes have been designed for the rewritable version (parity-preserving code) and the read-only version (combi-code). For bit-detection in the rewritable format, a nonrecursive algorithm with PRML-like performance is devised. Finally, a new ECC code, called the picket code, was designed in order to cope with multiple long burst errors, on top of the usual random errors of the channel.

Impact of ATM switch architectures on CBR video performance

Asynchronous Transfer Mode (ATM) has become one of the leading high-speed networking technologies in the local and wide area environments. ATM offers great promise to meet the real-time requirements of emerging multimedia applications. In the last few years, many ATM networks have been deployed and use different types of ATM switches, many of which differ in their implementations. In this paper, we explore the impact of two ATM switches, namely DEC GIGAswitch/ATM and IBM 8265 on the performance delivery of real-time digital video over native ATM connections. We also demonstrate experimentally the effects of different types of cross-traffic (delivered over both UDP/IP and native ATM) network loads on end-user application performance using QoS metrics such as jitter and packet loss.

A network MPEG camera

A network MPEG camera which can be directly connected to a network for real-time digital video transmission has been developed. The camera works under TCP/IP protocol, and accepts remote control commands from PCs. The command set of the camera includes record/pause command, mode change command, zoom control command, bit rate control command, and so on. The bit rate of MPEG video bit stream can be changed even in the data transmitting and encoding period.

Supporting digital video in a managed wireless network

Several problems have to be overcome before personalized interactive video communication services over radio frequency networks can become a reality. The challenge of being able to support wireless video services is significant since video is generally recognized as being bandwidth-hungry, error-sensitive, and sometimes delay-intolerant; radio channels, on the other hand, are characterized as having limited capacity and high bit error rates, and being time-varying. Under such hostile conditions the author explores issues in supporting real-time digital video communications over infrastructure-based wireless networks. The guiding philosophy behind the work described is that robust wireless video communications is possible if the different components within the network, operating system, and application layers cooperate with one another and with the overall system.

DVC decompression with denoising for picture quality improvement

Digital video cassette (DVC) is a quickly proliferating new standard for real-time digital video recording. DVC is presently used both in consumer and professional applications. In this paper we describe the DVC principles, data organization and video decoding algorithm. Although typically DVC video has very good quality, at low-light levels noise becomes pronounced. We show that noise in the DVC can be reduced by digital postfiltering. For this purpose, a wavelet denoising algorithm is suggested due to its unique properties. Wavelet denoising is described in detail and results of noise reduction are illustrated on examples.

Adding video into the (real)time domain

The use of video as a performance medium, concentrating on interactive digital video used synchronously with realtime interactive audio, is outlined. Specifically, the author's experiments with realtime video in Macromind Director and in Opcode's Max are explored, working with motion-sensing systems in performance environments. A number of experimental pieces using sonic and visual environments driven by realtime motion-sensing performance systems are described, using Max to re-map incoming sensing data and using Macromind Director to control MIDI sequences, digital sound files, and digital video in realtime. Some of the compositional challenges presented by realtime systems are also explored, particularly the compositional issues arising from the addition of video into the (real)time domain. The author's current work in the development of a CD-ROM published in 1996 is also explored. The CD-ROM attempts to provide a genuine degree of interaction significantly more sophisticated than the usual point-and-click navigation, allowing the viewer a degree of creativity in his or her interaction with the material.

Real time digital video image processing of in situ crystal growth

In this paper we present an investigation of processing real time video images of growing crystals. Using digital filters and transforms with a high speed computer system, we are able to recognize simple growth features as spirals or steps on a model compounds surface. Next we use a simple algorithm to calculate step velocities. These step velocities are measured as a function of supersaturation, showing a linear dependency.

Video compression using 3D wavelet transforms

This letter present results on using wavelet transforms in both space and time for compression of real time digital video data. The advantages of the wavelet transform for static image analysis are well known.2 We have found that using the wavelet transform in time and space, combined with a multiresolution approach, leads to an efficient and effective method of compression. In addition, the computational requirements are considerably less than for other compression methods, and are more suited to VLSI implementation. Some preliminary results of compression on a sample video will be presented.

High-resolution Kerr observation of magnetic domains

A high-resolution Kerr microscope was developed for observations of in-plane or perpendicular magnetized domains with widths down to 0.2 μm. Our main interest was to optimize the magnetization contrast, derived from the Kerr rotation and Kerr ellipticity, without anti-reflective coating of the magnetic surface. This is made possible by parallel argon laser illumination, a quarter-wave retarder, an imaging aperture matched to the resolution necessary and by optimized adjustment of the illumination and polarizing optics, controlled by a contrast-measuring difference photo-amplifier. The effect of laser interference patterns is minimized by a wobble plate which rotates in the beam. Real-time digital video image processing (512 × 512 pixels × 16 bit) allows subtraction of non-magnetic background and further contrast enhancement. Wall displacements are observed with a time resolution of 50 half-frames per second. Domains and their response to applied fields were investigated in magnetic microstructures.

High-Speed Techniques for Estimating T1, T2, and Density Images

This work presents methods for estimating relaxation times T1 and T2 and proton density using a real time digital video processor. This device performs each mathematical step of the fitting algorithms in one video frame interval (1/30 s). Two-point fits of T1 and T2 may be generated in approximately 15 video frame intervals or about 0.5 s; generation of a T2 image from four acquired images requires about 30 video frame intervals or about 1 s. The hardware is common to many commercial MR scanners and requires no array processor. Such high-speed techniques can expedite the clinical use of computed images and facilitate the implementation of image synthesis.

Wide Band Recording Characteristics of Perpendicular Magnetic Recording

The read after write characteristics of wideband signals for realtime digital video recording and high-speed transmission in perpendicular magnetic recording were compared at different relative velocities. Almost the same normalized output was obtained at relative velocity V = 5.2 m/s and at V = 20.4 m/s, but it was slightly lower at V = 15.6 m/s, going down to the short wavelength range, which seemed to be due to head friction causing slightly bad contact at V = 15.6 m/s resulting in increased space loss. It was found that the wideband C/N variation trends with respect to the relative speeds differ according to the recording wavelength.

A new system for LEED intensity measurements using a real-time digital video processor

A new system for low-energy electron diffraction (LEED) intensity measurements has been developed using a video camera and digital processing of the video signal. Complete two-dimensional LEED patterns are digitized in real time with high resolution using a commercial video processor. Intensity-voltage (I-V) data on all beams in complex LEED patterns are collected simultaneously. A microcomputer analysis program automatically tracks the diffraction beams as a function of energy and calculates beam position, size, and integrated intensity, including a local background correction. Using a video tape recorder for intermediate data storage, a complete set of I-V curves can be collected in less than 100 s.

Diagnosis of Cardiovascular Disease by Digital Subtraction Angiography

Recent advances in real-time digital video processing have led to a practical method for intravenous arteriography. The digital subtraction technique, which detects small differences in the concentration of the iodinated contrast material injected, is relatively safe and does not usually require hospitalization of the patient. The technique can thus be used for serial evaluation of various clinical problems and for studying the natural history of certain disease processes, as well as for following therapeutic endeavors.

The Digital Video Effects (DVE) System

Modern technology has made available digital real-time video processing units which can produce many of the effects previously limited to optical techniques. As the video processor is generally required to be used with a production switcher to complete the desired effects, it would be possible to integrate the two functions and simplify the operator interface. The Digital Video Effects or DVE system, comprising an NEC (Nippon Electric Co., Ltd.) digital video processor (FS-15, DVP-15 combination) and a special interface unit, has been successfully integrated with the GVG 1600 series of production switchers. This has been achieved with a minimum of additional controls by the use of an interface which examines the status of the production switcher and processes this data to activate the required control lines to the video processor. A novel auto-mask feature has been included which can be used to produce a tracking mask key.

Real-Time Video Compression Algorithm for Hadamard Transform Processing

A real-time digital video processor using Hadamard transform techniques to reduce video bandwidth is described. The processor can be programmed with different parameters to investigate various algorithms for bandwidth compression. The processor is also adaptive in that it can select different parameter sets to trade-off spatial resolution for temporal resolution in the regions of the picture that are moving. Algorithms used in programming the system are described along with results achieved at various levels of compression. The algorithms relate to spatial compression, temporal compression, and the adaptive selection of parameter sets.

Digital Video Data Transmission System for Photometric Television

A television system to measure broadband spectral intensities of stars and their coordinates has been developed for an experiment in the Orbiting Astronomical Observatory. The satellite provides three different methods of telemetry data transmission, but none of them is really suited for video transmission: real-time digital transmission is too slow; on-board data storage has too small a capacity; and real-time analog transmission is not sufficiently accurate. By development of special digital scan techniques for television, real-time data processing on board became feasible, and real-time digital video transmission was chosen as the prime mode. Also, additional small modifications of the television system made it possible to utilize the other two remaining available methods for video transmission as backup modes of operation. The particular technique is applicable to many space experiments, and many existing satellites can be converted to a television carrier without major modification.