Source coding for digital HDTV terrestrial broadcasting

It is claimed that an all-digital system will provide true high-definition television quality and coverage area equivalent to NTSC without noise and interference. Less transmission power may be required, and the signal will be easy to encrypt. The proposed source coding algorithms are reviewed, and the methods by which they are used in the proposed digital HDTV terrestrial broadcasting systems are discussed     

Channel coding for digital HDTV terrestrial broadcasting

In order to transmit the HDTV signal in 6 MHz, the four United States digital HDTV proponents, the DigiCipher, DSC-HDTV, ADTV and ATVA-P systems, are reducing the video data rate of HDTV to 15-17 Mb/s, a compression ratio of approximately 60-70 times. The high compression dictates that channel coding be used to avoid block errors and multiframe error propagation. High efficiency in channel utilization required by the 6-MHz limitation means that the channel must be properly equalized and that the multipath and interfering signals must be severely limited. The channel coding techniques used for error reduction include data interleaving, error detection and replacement, and error correction at different levels of protection for bits and blocks of unequal importance     

Compatible coding of digital interlaced HDTV

A compatible coding scheme for interlaced HDTV (high-definition television) is proposed. This scheme provides a standard definition signal and a second channel containing the additional information required to reach the HD resolution. The global scheme is of the pyramidal type: the standard TV is obtained by downsampling the HDTV signal by means of a field-based operation. The standard TV signal is coded, decoded, and upsampled. It is used as a prediction of the HD signal and the prediction error is coded in a second channel. In both branches, motion-compensated hybrid DCT coding is used. In addition, the DCT is taken within the frame     

Channel coding scheme for in HDTV digital VCR

The authors have developed an experimental in HDTV digital videocassette recorder (VCR). The VCR can record HDTV digital base-band signals for more than 64 min on a in metal particle (MP) tape. An eight-to-eight modulation ( ) scheme has been developed for this VCR to realize high-density recording. In order to suppress sufficiently the low-frequency components and reduce the occurrence probability of long-run-lengths for the recording data sequence, a new conversion table and bit-rearrangement method have been introduced in this modulation scheme. This conversion table has been particularly structured to reduce run-length using the bit-rearrangement process. Three kinds of typical HDTV images were used to evaluate the performance compared with the scrambled-NRZ method. The run-length distribution and the frequency spectrum were calculated for each image. The results showed that the occurrence probability of long-run-lengths were well reduced and the low-frequency components along with the DC component were sufficiently suppressed. Cross-talk interferences and overwriting noises were also found to be much less than those for the scrambled-NRZ method.     

Variable length coding of interleaved DCT coefficients for digital HDTV

This paper proposes an algorithm to redcue the bit-rate for transmission of the quantized DCT coefficient data in digital HDTV coders. The variable length coding compresses the quantized DCT coefficient data by removing their statistical redundancy. Zigzag scan is an effective way to improve the performance of the variable length coding. In order to reduce bit-rate further, we propose a new scanning method. Each DCT block is classified into the interleaving group and the non-interleaving group according to the number of non-zero DCT coefficients, and the DCT blocks in the non-interleaving group are encoded using the segmentation and interleaving of DCT coefficients, and the DCT blocks in the non-interleaving group are encoded using only zigzag scan. Simulation results show that the proposed method improves the bit-rate reduction performance by 6.8% when compared with the conventional method.     

Multiresolution broadcast for digital HDTV using jointsource/channel coding

The use of multiresolution (MR) joint source-channel coding in the context of digital terrestrial broadcasting of high-definition television (HDTV) is shown to be an efficient alternative to single-resolution techniques, which suffer from a sharp threshold effect in the fringes of the broadcast area. It is shown how matched multiresolution source and channel coding can provide a stepwise graceful degradation and improve the behavior, in terms of coverage and robustness of the transmission scheme, over systems not specifically designed for broadcast situations. The alternative available for multiresolution transmission through embedded modulation and error correction codes are examined. It is also shown how multiresolution trellis-coded modulation (TCM) can be used to increase coverage range. Coding results and simulations of noisy transmission are presented, and tradeoffs are discussed     

Source coding, channel coding and modulation techniques used in thedigital spectrum-compatible HDTV system

The digital spectrum-compatible high-definition television (DSC-HDTV) system, a digital HDTV simulcast system designed for United States terrestrial broadcasting on currently unassignable channels, is described. The system uses progressively scanned source signals and is characterized by an effective, high-performance video compression system. Compression includes motion compensation with hierarchical block matching and block transform coding with adaptive quantization according to perceptual criteria. Video compression is designed to simplify the receiver decoding; only a few VLSI chips and only one full frame memory are required. The source signal, source coding, channel coding, modulation, and performance of the system are discussed     

Source coding and transmission of HDTV images compressed with thewavelet transform

Digital high-definition TV (HDTV) signals are generally compressed to reduce transmission bandwidth requirements. A compression algorithm for the bit rate reduction of an HDTV image using the wavelet transform is presented. The major problems related to the transmission of a compressed HDTV signal are analyzed. Transmission is examined both on a noisy channel and an asynchronous transfer mode (ATM) network. The effects of channel noise on the reconstructed image are determined, and a solution to mitigate the degradation of the image quality is presented. A model for the output bit rate of the HDTV coder is derived and used to simulate the transmission of an ATM multiplexer so that the network's main performance parameters can be determined     

Practical coding for QAM transmission of HDTV

It is demonstrated how modulation schemes based on QPSK can be directly incorporated into QAM-based systems. It is argued that this leads directly to an easily implementable structure that is both efficient in bandwidth and data reliability. It is contended that the correct solution to the concatenated coding problem for HDTV transmission is to simply extend the modulation codes developed for QPSK-to-QAM modulation. In nonconcatenated situations, a trellis code based on a binary code at rate 2/3 is usually best. However, this is not the case for higher error rates at the output of the trellis decoder (e.g., when a symbol error correcting decoder follows as a concatenated code). The reason for this follows from an analysis of the effect of the number of nearest neighbors on the error rate. A four-way partition of QAM is a natural extension of QPSK modulation; it is a simple matter to incorporate any good QPSK code into a trellis coding scheme for QAM modulation. A concatenated coding scheme based on QPSK trellis codes and symbol error correcting coding is proposed. An example is presented to show the advantages of this approach     

HDTV evolves for the digital era

HDTV was created in an era of analog TV, seeking higher performance through the enhancements feasible in such an environment, such as higher resolution. The digital era is now in place, bringing compression and other processing enhancements, along with a new order of requirements, possibilities, and constraints for TV systems. HDTV in this era has a new meaning, with very different criteria being established. The paper traces the development of HDTV and details current work to establish HDTV systems appropriate for evolving and future digital application     

Modulation for terrestrial broadcasting of digital HDTV

The digital modulation methods used by the DigiCipher, DSC-HDTV, ADTV, and ATVA-P digital high-definition television (HDTV) systems are discussed. Three of the systems use a quadrature amplitude modulation method and the fourth uses a vestigial sideband modulation method. The channel equalization and spectrum sharing of the digital HDTV systems is discussed     

Professional HDTV digital recorder

Some of the essential technology for record/playback systems in professional HDTV digital recorders is described. The full bandwidths of 1125/60 HDTV signals (30 MHz for luminance and 15 MHz each for the two color difference signals) were recorded. An 8-8 mapping channel code and integrated detection were used. A special phase locked loop (PLL) to cope with picture search functions was developed. At the high data rate of 148.5 Mb/s per channel and the high linear density of 0.345 μm per bit, the recorder operates with a word error rate of less than 10^-4      

Multicarrier modem for digital HDTV terrestrial broadcasting

A digital modulation system using orthogonal frequency division and multiplexing (OFDM) is addressed in this paper. Such a system presents the advantage of coping with echoes more easily than classical single-carrier modems, thanks to the insertion of a guard interval between two symbols. The signal equalization is then achieved in the frequency domain. This OFDM modem is improved by using dual polarizations. In this configuration, it can convey a 70 Mbits/s (HDTV) bit stream in an 8 MHz UHF channel. Some experimental results relate field trials carried out in several countries with such equipment.     

The challenges of digital HDTV

The characteristics of digital high-definition television (HDTV) and its advantages over analog and hybrid systems are described. The issues to be addressed in using digital transmission in the terrestrial broadcast environment are examined. Four proposed digital HDTV systems are discussed, and their similarities and differences are highlighted. Key techniques are the use of complex compression coding and motion compensation algorithms     

Performance evaluation of MPEG-2 video coding for HDTV

We examine the subjective and objective performance of HDTV coded using the MPEG-2 video coding standard. Tests were conducted on seven HDTV sequences selected to cover a broad range of program materials in terms of scene content, complexity, motion speed and direction. The selected material was digitized in a 4:2:2 format with HDTV resolution and coded using the MPEG-2 main profile/high level syntax. Formal subjective assessment was performed by non-expert viewers on the sequences coded at a bit rate of 18 Mbits/s. Since MPEG-2 allows a great flexibility at the encoding end, we also examined the impact of various MPEG-2 encoding parameters on the quality of the reconstructed HDTV video sequences. The parameters include bit rate, the structure of picture organization, as well as temporal processing     

HDMAC coding for MAC compatible broadcasting of HDTV signals

The authors consider the problem of bandwidth reduction needed to allow HDTV (high-definition television) signals to be transmitted through the narrow DBS (direct broadcast by satellite) channel and to simultaneously fulfil the compatibility requirement with the European DBS transmission standard, the MAC/packet family. This problem is studied in the context of the EUREKA 95 project. The HDMAC coding system is outlined; it is a three-mode system (stationary 80 ms, tracking 40 ms, and dynamic 20 ms modes) with motion compensation used in the 40 ms mode. The system was built in hardware and has been demonstrated     

FLC and VLC coding for professional digital HDTV recording — Application to D1-like recorders

Digital recording is a key issue for HDTV studio applications. However, digital baseband recording of HDTV has some drawbacks, for example, high tape consumption and the fact that 1.2 Gbit/s recorders are close to technology limits. Bit-rate reduction techniques allow these difficulties to be overcome. This paper deals with two different approaches for picture coding suitable for professional HDTV recording, with special attention paid to compatibility with existing D1 VCRs (video cassettes recorder). The first approach considers that the behavior of a recorder requires FLC (fixed length code) data as opposed to VLC (variable length code) data, and the second approach supposes that the problems generated by use of VLC data can be overcome with preanalysis and extra error protection strategies. Comparisons of efficiency are presented including multiple copying.     

Flexible and robust packet transport for digital HDTV

The packet-oriented transport approach used in the advanced digital television (ADTV) system for terrestrial HDTV broadcast is described. ADTV achieves robust HDTV delivery on terrestrial simulcast channels via MPEG video compression, prioritization of MPEG data, and `cell-relay' type packet transport in conjunction with a two-tier physical transmission scheme. General design issues relevant to the development of the proposed transport protocol are discussed. ADTV's prioritization algorithm for partitioning MPEG-encoded video into high-priority (HP) and standard-priority (SP) bit streams is outlined. The data transport format supporting these prioritized compressed video bit streams is described. The three principal sublayers of the ADTV transport protocol are discussed in terms of specific functions, impact of system performance, and hardware implementation factors. A proof-of-concept simulation model that incorporates transport encoding and decoding functionality is outlined, and performance evaluation results are given for illustrative transmission scenarios