NTSC Video Research Articles

Multi-path equalization for NTSC video by using digital IIR filter

The multipath channel is modeled as an analog linear system with a response of complex weighted impulses of various relative delays. The effect of radio-frequency-to-baseband conversion is included. The minimum mean square error criterion is used to find a digital FIR approximation of the analog channel. The digital IIR equalization filter is selected to be the inverse of the FIR approximation; it can minimize ghost interferences with minor sacrifice of the random noise part. A simple sufficient condition for stability of the IIR deghosting filter is presented. A configurable IIR filter architecture using a crossbar network is described. A priori knowledge of the sync waveform is applied to synthesize a ghosted sync as a function of the channel parameters.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

An experimental color-under VCR for IDTV/EDTV system

An experimental color-under VCR for improved-definition TV/enhanced-definition TV (IDTV/EDTV) systems which can record and reproduce the full NTSC-bandwidth TV signal has been developed. To be adaptable for IDTV/EDTV systems, the VCR should have a full NTSC bandwidth (4.2 MHz) and standard NTSC output (without skew and jitter). In current VCRs the bandwidth of the reproduced signal is not generally sufficient to meet above requirement. Improvement has been achieved by reproducing the high-frequency luminance signal included in the color-under chrominance signal without any amplitude and phase distortion, providing full NTSC video bandwidth without any time base error. A 330-line-resolution picture has been obtained with an IDTV set. >

The Usable Intersection of PC Graphics and NTSC Video Recording

There are many reasons for users of computer graphics to want to distribute and/or record their output on standard television equipment: in-house documentation of user interfaces, teleconferencing, presentations to groups, and quality media production, to name a few. Unfortunately, most raster graphics devices do not, in fact, generate NTSC video as well as a cheap videocassette recorder or home color video camera does. High-resolution (e.g., 1024 x 1024) and noninterlaced 60-Hz displays designed for direct viewing do not adhere to NTSC standards because they grossly surpass the NTSC bandwidth. Display boards for PCs that generate raster images at equal or less resolution than NTSC video, including those that are able to use NTSC television monitors, vary greatly in video recordability. Even those devices claiming to be NTSC compatible often have severe detail errors in the signal; some errors can be easily corrected with post-production video equipment, while others make the signal difficult to record and edit. This article exposes the problems created by nonstandard video on PCs, proposes many solutions, and offers a detailed case study of one particular system.

Unrecordable Video

Proposed in this paper is a scheme to modify NTSC video signals to render the signal unrecordable by video recorders, yet viewable on standard television displays. This method is based on continually varying timing characteristics in the transmitted video signal. Protection of copywrited broadcast material from casual consumer or illicit professional recording would be possible with this implementation. A means of neutralizing this protection scheme would require extensive signal buffering and analysis hardware currently beyond the reach of nearly all unauthorized parties.

Low cost scientific video movie making

A low cost video movie making system is described. The system consists of a PC microcomputer based animation controller, video frame buffer, and 1 2″ editing video tape recorder. The graphic data typically generated on mainframe computers is transferred over a local area network to the PC, there to be recorded, one frame at a time, to produce a video tape movie. The characteristics and limitations of the system are discussed, together with implications of encoding graphic primitives in an NTSC video signal. The use of the system for scientific movie making is described.

An Introduction to EIA IS-15 Standard Baseband (Audio/Video) Interface Between NTSC Television Receiving Devices and Peripheral Devices

An Introduction to EIA IS-15 Standard Baseband (Audio/Video) Interface Between NTSC Television Receiving Devices and Peripheral Devices

Component Compositing in Post-Production

This article discusses some of the operational processes and problems inherent in the post-production compositing of digitally generated graphic environments and live action videotape. The compositing of the images was performed in post-production, from videotape source material. Ultimatte™ and conventional keying processes were compared, using analog component and conventional NTSC video. Some of the design issues considered include scene synthesis, shadows, highlight, detail, perspective, and reflections. It was found that the use of a digital paint system with multiple layering, digital video effects, and switcher transitions allowed more realistic object representation.

A New Architecture for Adaptive Intrafield Transform Compression of NTSC Composite Video Signal

In orthogonal transform coding of NTSC video signal, the data are processed in blocks. Processing a block of data that is maximally correlated leads to larger compression. This correspondence describes a new architecture for arranging the pixels in a block that yields higher correlation than the adjacent pixel blocks. The data are processed using adaptive, intrafield, discrete cosine transform, variable bit allocation coding. In subjective tests good quality pictures were obtained for an average of about 2 bits/pel for intrafield processing.

NTSC and MAC Television Signals in Noise and Interference Environments

Probleme des bruits et interferences dans les futurs systemes de radiodiffusion directe par satellite. Resultats d'un programme de mesure en deux phases de ces effets sur la qualite de l'image. La premiere phase evalue les effets sur un signal NTSC-MF, la seconde sur un signal MAC

Movement Compensated Interframe Prediction for NTSC Color TV Signals

This paper presents techniques for interframe prediction of color NTSC signals using motion estimation and compensation techniques. A key element in movement-compensated prediction is the displacement estimation algorithm. A number of techniques for performing this estimation have been presented in the literature [1]-[13]. Some new techniques giving improved performance are presented in this paper. Also, a movement-compensated composite prediction approach for coding of the NTSC color signals is presented. The performance of different displacement estimation algorithms is evaluated and compared for both component and composite approaches. A database of several color NTSC video sequences is used in the evaluation.

Digital Audio Modulation in the PAL and NTSC Laservision Video Disc Coding Formats

We present an extension of the current LaserVision video disc format that includes a digital audio signal. We show the feasibility of a combined digital audio signal according to the Compact Disc Digital Audio format and the current analog audio signals in the NTSC video format, enabling the realization of a compatible system. For the PAL and SECAM video formats we show the feasibility of digital audio, but unfortunately it cannot be combined with the analog audio carriers.

SNR Fluctuation and Nonlinear Distortion in PFM Optical NTSC Video Transmission Systems

The causes of SNR fluctuation and nonlinear distortion, uncovered during field trials of PFM optical video transmission systems, are investigated theoretically and experimentally. Degradations are found to be significant in long distance transmission at a wavelength around 0.85 μm. This is because PFM pulse jitter closely relating to the degradation is caused by laser mode competition and its interaction with fiber material dispersion. However, at a wavelength around 1.3 μm, where fiber material dispersion is negligible, only small nonlinear distortion due to feedback light from connectors is observed. Thus, good picture quality is maintained over long distance transmission.

Predictive Coding of Composite NTSC Color Television Signals

A study is reported of intrafield predictive coding of composite NTSC television signals sampled at four times the color subcarrier frequency (14.3 MHz). The choice of predictor was found to be governed by three constraints, which are described. Of several predictors which satisfied these constraints, it was determined that one of them performed the best. A procedure for designing quantizers for composite signals was developed based on a three-parameter piecewise-linear approximation to the quantizer error threshold function. Observations of picture quality were made using real-time processing on a mixed hardware/software experimental facility, from which it was concluded that between 5 and 6 bits/pel were required for broadcast quality. Preliminary results were obtained on the effect of composite predictive coding on the vertical interval test signals (VITS). Our observations indicate that the waveform distortion criteria applied to VITS give some indication of granular noise visibility (in the SNR measurements); these criteria, however, are too severe in their requirements for slope overload distortion and do not consider edge busyness, an important temporal impairment in predictive coding.

An architecture for hybrid coding of NTSC TV signals

A hardware feasible architecture for DCT/DPCM hybrid coding of color television (TV) signals has been developed. The coding system is based on formatting four horizontal scan lines into blocks of the same subcarrier phase elements. The samples in each block are rearranged and transformed by a FDCT processor. Based on its average energy, a given transform block is compared with its adjacent blocks and the nearest block is selected as its estimate. The difference between the actual and the estimated values of the (DCT) coefficients are then quantized and encoded using nonuniform quantizers and a variable length coder. Furthermore, the maximum number of different wordlengths is assumed to be five. Therefore, five sets of 256-byte encoding ROMs are used to store the quantization tables. To reduce the redundancy in the code words, an adaptive coding scheme is used. The coding scheme is based on setting two threshold levels.

Sampling and Reconstruction of NTSC Video Signals at Twice the Color Subcarrier Frequency

Methods for sampling and reconstruction of NTSC video signals at twice the color subcarrier frequency are described and evaluated. A scheme for sampling NTSC signals is characterized by the horizontal sampling frequency and the spatiotemporal sampling structure. For a given sampling frequency, the sampling structure should be chosen to permit the best subjective reconstruction of the analog signal. This paper presents a three-dimensional analysis of sampling structures suitable for sampling NTSC signals at twice the color subcarrier frequency, and describes a method for designing the reconstruction filters. Three sampling schemes were simulated on a number of sequences of NTSC video, and evaluated in a subjective test. The field quincunx (QT) sampling structure was found to give best results. There was no detectable subjective difference between the original and reconstructed sequences in most cases. Minor degradations were detected for some critical images, upon close inspection.

Digital Frame Memory for Still Picture Television Receivers — PASS Encoding System and Application

A new form of television broadcasting is proposed. It consists of the transmission of a series of color still pictures accompanied by their individual sound complements. To this effect, the still picture receiver must incorporate a frame memory for the storage and repeated readout of a given program picture until a new picture signal is received. Single-chip 64K-bit CCD memories are now commercially available (among other memory devices) and may provide for a quite economical frame memory of small size, well suited for the purpose. Phase Alternating Sub-Nyquist Sampling (PASS) is used for the digital recording of NTSC video signals. This reduces the bit rate and the amount of memory required. The principles of PASS encoding are explained. Three types of interpolation filters, needed for the suppression of aliasing, have been investigated. A two-dimensional analysis of PASS encoding is discussed in the paper. Three PASS encoding methods are described in detail: (1) field alternation; (2) one-line alternation; and (3) two-line alternation. An outline of the practical design of an experimental digital frame memory for a still picture television receiver is given. With this design, actual picture signals appeared good. Vectorscope color bar displays before and after processing by the frame memory showed good coincidence.

Teletext and viewdata systems and their possible extension to the USA

The UK teletext and viewdata systems are analysed as a basis for discussion of their suitability for incorporating in the North American NTSC television system. Methods for adapting to the different band width and display format requirements are described which indicate the feasibility of immediate implementation in the USA. An interim teletext test transmission system to assist in the choice of a suitable data rate and general system parameters is outlined. The cost implications of adopting the basic UK systems, which are already well established, are reviewed in some depth. The flexibility of the present teletext system and its potential for future extensions is discussed and it is shown that initial decoder designs will not be made obsolescent when these are implemented. It is concluded that, with a suitable choice of data rate and page format, the UK teletext and viewdata systems form a sound basis for the establishment of these services on the NTSC system in USA.

A New Optical Videodisc System with One Hour Playing Time

A series of papers proposing a possible format for reflection-type optical videodisc systems was published in 19761-3. Principal parameters of the format (with NTSC standards) are as follows: the disc rotation speed is 1800 rpm, the track-to-track pitch is 1.67?m, and the playing time is 30 minutes from one side of a 12-inch-diameter disc. A direct frequency modulation of the composite NTSC video signal is employed, with the attractive feature that the full extent (4.2 MHz) of NTSC luminance bandwidth can be retained in this format.

Automated and Digital Measurement of Baseband Transmission Parameters

Advanced digital technology has made possible the development of a new digital automatic television test-signal measuring system, which has been designated ANSWER II. Five years ago, the first ANSWER system was not put into production because its analog methods were too complex (digital technology was not yet available). The heart of the ANSWER II system is an 8-bit, 20-MHz analog-to-digital converter (ADC) developed by Tektronix, Inc., for NTSC and PAL television. The latest integrated-circuit technology was used to achieve the best possible performance. During the development of the ADC, microprocessors (computers-on-a-chip) and programmable read only memories (PROMs) became commercially available and were incorporated into the design. One important specification of the system is that it employs digitization at four times the subcarrier frequency. Specific measurement programs may be changed merely by changing the PROM(s). Several important applications are envisioned and the possibility is noted that ANSWER II may ultimately replace the oscilloscope and vectorscope for many broad case engineering applications.

Digital Coding of Color Video Signals--A Review

This paper reviews the field of the efficient coding of color television signals. Because this paper is perhaps the first review on this topic, some background is given in the areas of colorimetry, visual perception of color and color television systems. We assume that the reader has some familiarity with luminance encoding techniques. Coding techniques themselves are divided into two broad groups: component coding methods in which each component (usually three) is coded separately, and composite coding methods in which the composite television signal with its "color" modulated subcarrier is processed as a single entity. Both approaches are covered in detail. The field is still growing, pushed primarily by the desire in the television area to find digital coding standards accepted by both broadcasters and carriers and suitable for use with NTSC, PAL and SECAM television systems. We discuss this aspect by comparing composite and component coding methods.