1、STD-ITU-R RECMN BT*LLLB-L-ENGL 1797 W 4855232 0533733 437 W Rec. ITU-R BT.1118-1 101 RECOMMENDATION ITU-R BT. 1 1 18-1 ENHANCED COMPATIBLE WIDESCREEN TELEVISION BASED ON CONVENTIONAL TELEVISION SYSTEMS (Question ITU-R 42/1 i) (1 994- 1997) The IT Radiocommunication Assembly, considering a) broadcast
2、ers are therefore committed to maintaining the existing service; that both broadcasters and viewers have a large investment in equipment for conventional television, and b) competition; that many broadcasting organizations may wish to enhance the quality of their existing services to meet c) and sou
3、nd, including wider aspect ratio; d) e) that there are proposais to introduce new systems of television broadcasting with improved quality of picture that the quality goal for such new services has been defined in Recommendation IT-R BT.1127; that the introduction of such new enhanced services will
4、be supported by some existing production equipment; f) receivers and new studio equipment; g) life expectancy to justify investment in all areas of the broadcasting system; h) that modem technology allows cost-effective integration of enhancement technology into new consumer that despite the advent
5、of advanced television services in the future, enhanced systems could have sufficient that a modular approach to enhancement will allow flexibility for broadcasters, manufacturers and consumers, recommends that for enhanced television: 1 optimized to suit the populations of existing 4:3 receivers an
6、d new 16:9 receivers); the display format should be 16:9. (As an interim arrangement the aspect ratio of transmitted images could be 2 the window technique may be used) when displayed on conventional 4:3 receivers; the transmission of wide aspect ratio images should use the letter-box technique (as
7、an interim arrangement, 3 transmitted should be carried within the nominal 6,7 or 8 MHz RF channel occupied by the conventional signal; 4 for conventional or enhanced receivers, should be the same as for conventional signals; any additional signals which may be required to convey information to rece
8、ivers for the enhancements being the minimum protection ratios and the transmission power required by the enhanced television signal, either 5 features listed in Annex 1 should be used, when enhancements to existing television systems are made, some or all of the modular enhancements and firther rec
9、ommends 1 considered acceptable with current broadcasting services in the VHF/UHF bands; that enhanced terrestrial television broadcasting should not cause interference subjectively greater than that 2 3 NOTE 1 - Administrations are invited to conduct further studies with the aim of making detailed
10、proposals. that the enthusiasm among creative staff for producing in 16:9 should be recognized and promoted; that the circumstances of developing countries should be given careful consideration in terms of priorities. COPYRIGHT International Telecommunications Union/ITU RadiocommunicationsLicensed b
11、y Information Handling ServicesSTD-ITU-R RECMN BT-LL18-1-ENGL 1777 4855212 O53373q 373 Rec. ITU-R BT.1118-1 ANNEX 1 Modules and features of enhanced television 102 When enhancements to existing NTSC, PAL or SECAM television transmission systems are made, some or all of the following modular enhancem
12、ent methods and features should be used according to the following: 1 Picture enhancement modules 1.1 - Preferred image format: 16:9, - - Coder requirements for accommodating wide aspect ratio signals method of format conversion from 16:9 to 4:3, method of preserving the vertical resolution informat
13、ion: - - - method of deriving additional information, method of processing the additional information, method of including the additional information in the broadcast signal. 1.2 - Method of luminance filtering, - method of chrominance filtering, - method of modulation, - Coder requirements for redu
14、cing cross-effects and making optimal use of the signal spectrum method of combining luminance and chrominance. 1.3 Ghost cancellation - Insertion test waveform, - position in the signal. 1.4 - - Coder requirements for increased resolution Method to derive extra information, method of including the
15、extra information in the channel. 1.5 Data signalling - - position in the signal, - data to be transmitted. Details of the data waveform, 2 Sound enhancement modules - - Details of sound coding technique, method of including the sound signal. 3 Other features - Methods to reduce impairments that mig
16、ht be created should also be taken into consideration; n the 4:3 conventional receivers by the enh n ement sign 1 COPYRIGHT International Telecommunications Union/ITU RadiocommunicationsLicensed by Information Handling Services103 Rec. ITU-R BT.1118-1 Y, c Format - the possibility of the need for in
17、-vision subtitles in the lower black part of the screen for existing 4:3 receivers without teletext decoders should be taken into account; +Hk7 - - the possibility of transmitting such an enhanced signai through the existing satellite-broadcasting service and other media should be taken into account
18、. A - Multi-dimensional conversion pre-coding processing The main features of such a system, emphasizing the modular approach, are shown in the block diagram given in Fig. 1. I 1 A Augmentation c signal FIGURE 1 Block diagram of an enhanced television encoder - Input wide aspect ratio signai Signall
19、ing signai Signalling for decoder control 413 aspect ratio signal Test signai for ghost cancelling Compatible baseband composite signai Ghost waveform processing I To videolsound mixing t- Sound -I processing Sound input - Component video 118-01 Table 1 provides a summary of methods and parameter va
20、lues for PAL and NTSC for the above optional enhancement modules. COPYRIGHT International Telecommunications Union/ITU RadiocommunicationsLicensed by Information Handling Services104 NTSC Rec. ITU-R BT.1118-1 TABLE 1 Parameter values or methods for enhancement modules PAL Optional modules Wide image
21、 aspect ratio Method for transmitting widescreen within 43 raster: - Widescreen source material i - Other source material Method for preserving vertical resolution I _ 1 Picture enhancements 1.3 1.1 1.2 Reduced cross effects: - Serving existing receivers - Serving new receivers Comb-filter encoders
22、Rec. ITU-R BT. 1298 Motion adaptive colour plus (see Rec. ITU-R BT.1197) 1.4 Making optimal use of the signai spectrum Ghost cancellation At the encoder, vertical/temporal pre-filtering from higher than 525/2: 1 or 6292: 1 rates Rec. ITU-R BT. 1 124 16:9 1.5 Letterbox Window or letterbox Vertical he
23、lper signais in the black bands (see Recs. ITU-R BT.1298 and ITU-R BT.1197) Increased resolution: - VerticaVemporal - Horizontal HH, Rec. ITU-R BT.1298 2 Sound enhancement 2.1 Digital multichannel sound Rec. ITU-R BS.707 VTNH, Rec. ITU-R BT.1298 I 1.6 I Widescreen signalling I Rec. ITU-R BT. 1 1 19
24、I Some enhancement methods are discussed in Annex- 2 for 625-line systems. ANNEX 2 Enhancement methods for 625-line systems 1 Picture enhancement techniques 1.1 Wide aspect ratio coding Two practical approaches to accommodating the wide aspect ratio frame in a conventional 4:3 signal are: 1.1.1 The
25、letter-box format Widescreen displays with a 16:9 aspect ratio are being made in Europe for enhanced television services. The most straightforward way to convey the 16:9 signal in the 425-line PALKECAM channel, and at the same time preserve the correct geometry for the viewer with a standard 4:3 rec
26、eiver, is to use a letter-box format. In this format approximately 432 of the 575 active lines are used to carry the 16:9 active picture area. COPYRIGHT International Telecommunications Union/ITU RadiocommunicationsLicensed by Information Handling ServicesRec. ITU-R BT.1118-1 105 In the widescreen r
27、eceiver, approximately 432 lines are arranged, by up-conversion or other means, to fill the full height of the display. In the standard 4:3 receiver the viewer sees black bands above and below the active picture. 1.1.2 Window options There are several possible choices for a compromise “letter-box” w
28、indow solution, and one of these could be the mean aspect ratio between 4:3 and 16:9, i.e., 14:9. In this case, the black bands displayed on a conventional 4:3 aspect ratio receiver would be reduced from the 12.5% of a 16:9 letter-box to some 6% of full picture height at top and bottom. However, in
29、practice, the viewer would be likely to see only about 2% black bands, due to the typical receiver overscan. In the case of the widescreen receiver, options could exist to allow the 14:9 picture to be displayed filling the full width of the visible screen by incorporating a small amount of geometry
30、error - typically 8%. 1.2 Reduction of cross-effects Two approaches have been considered for reducing cross-effects in the PAL system, known in broad terms as band segregation and phase segregation. Band segregation is the simplest method to understand because the luminance and chrominance component
31、s are separated in the frequency domain. A motion adaptive technique has been developed in Europe known as “motion adaptive colour plus” which has been designed to allow optimum chrominanceAuminance separation with both electronic camera and film sources. In the phase segregation method, high-freque
32、ncy luminance and chrominance signais are effectively carried on orthogonally-phased subcarriers. Both methods involve complex muiti-dimensional comb filter processing. It remains to be seen whether similar techniques can be applied in the SECAM system. 1.3 Ghost cancellation Proposals for ghost can
33、cellation require the use of a test line or “training” signal. Various possibilities exist for the form of the training signal. (See Recommendation IT-R BT. 1124.) 1.4 Increased resolution In the circumstance where the source signal standard contains more resolution than conventional composite signa
34、ls, there are proposals to include this information in the compatible enhanced signal. Such information might be accommodated by spectrum folding techniques and conveyed in the signai by coding methods such as: - - - - quadrature modulation of the vision RF carrier, signais carried in the video spec
35、trum to take advantage of the Fukinuki hole in vision, signals carried in the vertical blanking interval, - signals carried at the extremities of each active picture line, that would not normally be visible on conventional televisions due to overscan. 1.5 Data signalling At its simplest, data signal
36、ling is desirable that would indicate to the receiver the aspect ratio of the transmission. The enhanced encoder would in addition need to convey other information to the decoder. For example, the status of the coder processing methods, the film or camera mode, if such improvements are incorporated
37、in the system, to the decoder. Refer to Recommendation IT-R BT. 11 19. 2 Sound coding It is expected that improved quality sound coding, by digital means, will form an important enhancement to the broadcast composite signal. The choice of technique needs to be made in association with other requirements in the signal. (See Recommendation -R BS.707.) COPYRIGHT International Telecommunications Union/ITU RadiocommunicationsLicensed by Information Handling Services
