1、 - STD*ITU-R RECMN BT-LZ78-ENGL 1997 9 Li855222 0533797 T22 9 Rec. ITU-R BT.1298 115 RECOMMENDATION ITU-R BT. 1298 ENHANCED WIDE-SCREEN NTSC TV TRANSMISSION SYSTEM (Question ITU-R 42/11) ( 1997) The Radiocommunication Assembly, considering that the 16:9 aspect ratio provides an enhanced viewing expe
2、rience, particularly on large screen receivers, and a) is likely to be adopted for new digital services; b) c) d) wide-screen receivers whilst maintaining compatibility with existing 4:3 receivers (using 169 letterbox); e) that the signalling system required by EDTV-II for receiver control has been
3、recommended in Recommendation ITU-R BT.1119; that there are indications that the public interest in the new 16:9 aspect ratio is growing; that NTSC services are likely to continue for the time being, whatever new services are introduced; that the enhanced definition television (EDTV-II) system can p
4、rovide high quality 16:9 pictures for enhanced f) made, some or all of the modular enhancements and features listed in Annex 1 to that Recommendation should be used; that Recommendation ITU-R BT. 1 1 18 recommends that when enhancements to existing television system are g) further that three of thes
5、e modules and features are: coder requirements for accommodating wide aspect ratio signals, coder requirements for increased resolution, methods to reduce impairments that might be created on the 4:3 conventional receivers by the enhancement signals; that EDTV-II system provides for the three module
6、s and features listed in $ g), recommends - - - h) 1 NTSC system M) television with compatible wide-screen, the EDTV-II system, as specified in Annex 1, should be used. that where administrations or broadcasters wish to enhance the delivery of conventional NTSC (in the case of ANNEX I EDTV-II system
7、 specification CONTENTS 1 Introduction 2 Features of EDTV-II transmission system 2.1 2.2 2.3 2.4 Wide-screen signalling system 2.5 Chrominance signal, audio signal Vertical conversion to 360-line letterbox picture Enhancement by vertical helpers (VH, VT) Enhancement by horizontal helper (HH) COPYRIG
8、HT International Telecommunications Union/ITU RadiocommunicationsLicensed by Information Handling ServicesSTD-ITU-R RECMN BT-LZ78-ENGL 1777 P 9855232 05337q8 7bd H Enhancement Mandatory or optional in EDTV-II - Letterbox Mandatory 116 Rec. ITU-R BT.1298 Vertical temporal helper (VT) Horizontal helpe
9、r (HH) 3 Input signal formats for EDTV-II transmission system Optional() OptionaP) 4 Wide-screen technique of EDTV-II Ghost cancellation reference signal 5 EDTV-II techniques for enhancement of picture quality 5.1 Enhancement technique for vertical resolution 5.1.1 Vertical high resolution helper (V
10、H) 5.1.2 Vertical-temporal helper (VT) 5.1.3 Multiplexing of VH and VT Enhancement technique for horizontal resolution Interference visibility reduction techniques in multiplexing the vertical helpers 5.3.1 5.3.2 Adaptive set-up level control 5.2 5.3 Gain control by correlation in active image area
11、Optional 6 Signalling Appendix 1 to Annex 1 Recommended practices 1 Introduction The second generation EDTV (EDTV-II) is an enhanced wide-screen NTSC transmission system, which provides existing NTSC broadcasters with wide-screen (16:9 aspect ratio) and high picture quality, while maintaining the co
12、mpatibility with NTSC transmission system and with existing NTSC receivers. The first generation EDTV (CLEARVISION) was recommended as Recommendation ITU-R BT.797. CLEARVISIONs enhancement modules are optional to EDTV-II, and the modules are equally applicable to both conventional NTSC and EDTV-II s
13、ignals. 2 Features of EDTV-II transmission system An EDTV-II signal is derived using some or all of the processes as listed in Table 1, and illustrated in Fig. 1. The vision signal shall be described as “EDTV-II” both when one or more helpers (VH, VT and HH) are used and when the wide- screen signal
14、ling (Annex 2 to Recommendation ITU-R BT. 11 19) is used. TABLE 1 The enhancement features incorporated in EDTV-II transmission I Vertical high resolution helper (VH) r- Optional() 1 I Wide-screen signalling -I I Mandatory COPYRIGHT International Telecommunications Union/ITU RadiocommunicationsLicen
15、sed by Information Handling Services STDaITU-R RECMN BT-1278-ENGL 1777 LI855212 05337q7 AT4 1 t 111- v 117 Rec. ITU-R BT.1298 t -ri f q t - 1 M T COPYRIGHT International Telecommunications Union/ITU RadiocommunicationsLicensed by Information Handling Services STD-ITU-R RECMN BT-3278-ENGL 1797 485523
16、2 0533750 5Lb 118 Rec. ITU-R BT.1298 2.1 This is the conversion of the 16:9 aspect ratio source picture with 480 active lines to a 16:9 aspect ratio letterbox picture with 360 active lines. Vertical conversion to 360-line letterbox picture 2.2 The helpers for vertical high resolution are transmitted
17、 taking advantage of the black bands above and below the active picture area. The vertical helper (VH) signal carries the vertical luminance component higher than 360 lines per picture height in the still portion of the picture. VT carries the vertical temporal component in order to realize progress
18、ive scanning at the receiver. Both VH and VT modulate the colour subcarrier and are then transmitted in the black bands above and below the active picture area. Techniques are employed in an EDTV-II transmission in order to minimize the visibility on 4:3 receivers of the VH signals. The component ca
19、rried by VH or VT is shown in Fig. 2. Enhancement by vertical helpers (VH, VT) FIGURE 2 Resolution (for still and moving pictures) and components carried by VH, VT and HH O 1 07 448 640 Horizontal resolution (lines per picture height) 1298-02 2.3 The helper for horizontal high resolution is transmit
20、ted by using the “Fukinuki hole”. The horizontal luminance component between 4.2 and approximately 6 MHz is transmitted as HH by frequency division multiplexing into the active area of the letterbox signal. The component carried by HH is shown in Fig. 2. Enhancement by horizontal helper (HH) 2.4 Wid
21、e-screen signalling system The wide-screen signalling system provides for identification of an EDTV-II signal, and indicates which kinds of helpers are actually transmitted. The wave form of the signal and the assignment of the bits are described in Annex 2 to Recommendation ITU-R BT. 11 19. 2.5 Chr
22、ominance signal, audio signal The chrominance signal is transmitted in the active area of the letterbox after the conversion from source picture with 480 active lines to 360 active lines. The audio signal is completely the same as that of an NTSC system. The features of EDTV-II transmission are summ
23、arized in Table 1, COPYRIGHT International Telecommunications Union/ITU RadiocommunicationsLicensed by Information Handling Services - - STD-ITU-R RECMN BT.1278-ENGL 1797 W 4855212 0533751 452 W Rec. ITU-R BT.1298 119 3 Input signal formats for EDTV-II transmission system Signal formats 525/59.94/2:
24、1, 525/59.94/1:1 and 1125/60/2:1 are considered to be basic input signal formats. Other formats may be used for encoding after conversion to these basic input signal formats. At the receiving side, EDTV-II programmes can be displayed in the letterbox format on 4:3 NTSC receivers without decoding, an
25、d be displayed in wide-screen format on 16:9 progressive or interlaced scanning receivers. 4 Wide-screen technique of EDTV-II 16:9 aspect ratio pictures can also be viewed on existing 4:3 receivers by using the letterbox format as well as on 16:9receivers. In the encoder, 480 active scanning lines a
26、re converted to 360 active scanning lines by means of a 480 line to 360 line (4-3) converter. Specifically, 180 scanning lines per field are assigned to the centre part of the letterbox format for the active image area and 30 scanning lines per field are given to the black areas above and below the
27、active image area (see Fig. 8). In the wide-screen receiver, 16:9 pictures are reproduced by means of a 360 line to 480 line (3-4) converter. As described in 0 5.1.1, the 4-3 converter operates by vertical sample rate down conversion following a vertical low-pass filter for anti-aliasing. When the v
28、ertical high resolution helper (VH) is multiplexed, the vertical low-pass filter shown in Fig. 3 shall be used. The same filter can be used for anti-aliasing when the VH is not multiplexed. FIGURE 3 Frequency characteristics of low-pass filter and high-pass filter in relation to the active image are
29、a and VH of the letterbox signal m Y Vertical frequency (lines per picture height) Active image area VH - 1298-03 COPYRIGHT International Telecommunications Union/ITU RadiocommunicationsLicensed by Information Handling ServicesSTD-ITU-R RECMN BT-1278-ENGL i797 D 4855232 0533752 377 = Line number 120
30、 Rec. ITU-R BT.1298 Coefficient 5 EDTV-II utilizes the enhancement techniques for vertical resolution and horizontal resolution of luminance signals described below in order to transmit high quality wide-screen pictures using a letterbox format. Further visibility on 4:3 receivers caused by the vert
31、ical helpers is minimized by implementing interference reduction techniques in multiplexing the vertical helpers in the black areas. EDTV-II techniques for enhancement of picture quality 5.1 The vertical helper signal, which is transmitted to improve vertical resolution, is made up of both a vertica
32、l high resolution helper (VH) and/or a vertical-temporal resolution helper (VT). The vertical helper signal is multiplexed in the upper and lower black areas as shown in Fig. 8 and its signal level in these areas before multiplexing is set to O IRE units. In multiplexing the vertical helper signal,
33、the active image area portion of the letterbox signal is obtained by converting the active scanning lines from 480 lines to 360 lines, following the conversion from progressive scanning to interlaced scanning. Enhancement technique for vertical resolution 5.1.1 First, 480 active lines are limited in
34、 the vertical frequency domain by a high-pass filter, then their signal polarities are alternately reversed from the beginning of the scanning lines. After that, VH is generated by 480 to 360 scanning line conversion and progressive to interlaced scan conversion. VH is multiplexed only for stationar
35、y pictures. The high-pass filter has the following characteristics: - - In multiplexing VH, the active image area portion of the letterbox signal is obtained by converting the number of active scanning lines from 480 to 360 after limiting the vertical frequency bandwidth by a low-pass filter with th
36、e following characteristics: - - Figure 3 shows the frequency characteristics of the high-pass filter and the low-pass filter mentioned above. Line number (or position) of the signal which is sub-sampled for the progressive to interlaced scan conversion is the same both for VH and for the active ima
37、ge area signal. Vertical high resolution helper (VH) less than 1 dB down at 360 lines per picture height, greater than or equal to 20 dB down at 180 lines per picture height. less than 1 dB down at 180 lines per picture height, greater than or equal to 20 dB down at 360 lines per picture height. 5.1
38、.2 Vertical-temporal helper (VT) VT is obtained by limiting the vertical frequency bandwidth of the 360 active scanning lines using a high-pass filter (Hl(Z), and converting the scanning format from progressive to interlaced. The coefficients of the high-pass filter are shown in Table 2. TABLE 2 Coe
39、fficients of Hl(Z) (1 In1360) In multiplexing VT, the active image area signal in the letterbox signal is obtained by converting the 360 scanning lines from the progressive format to the interlaced format after limiting the vertical frequency bandwidth by a low-pass filter (Ho(Z). The low-pass filte
40、r has the coefficients shown in Table 3. COPYRIGHT International Telecommunications Union/ITU RadiocommunicationsLicensed by Information Handling Services STD*ITU-R RECMN BT.1298-ENGL 1977 m i855212 0533753 225 Rec. ITU-R BT.1298 TABLE 3 Coefficients of Ho(Z) Line number n-2 n- 1 n n+l n+2 (1 In1360
41、) Coefficient I -1/8 U8 121 Hl(Z) and Ho(Z) shall be used in conjunction with Gl(Z) and Go(Z) on the reception side, as shown in Fig. 4. This forms a SSKF with perfect reconstruction capability. Figure 5 shows the frequency characteristics of these filters. FIGURE 4 SSKF composition P-1 Low-pass fil
42、ter 360 p I I O insertion Low-pass filter 360 i Active image area - High-pass filter High-pass filter Black area Encoder Decoder _1 1298-O$ Regarding the line numbers which indicate the lines to be sub-sampled for the progressive to interlaced scan conversion both of the active image area and of VT,
43、 the VT line numbers are the same as the line numbers of the lines which should be interpolated in the active image area. 5.1.3 Multiplexing of VH and VT The following procedures shall be taken for multiplexing both VH and VT or either of them in the black areas. Step 1: are shown in Fig. 6. - - - C
44、any out band limitation for VH andor VT using a low-pass filter with the following characteristics. These less than 6 dB down at 0.8 MHz, greater than or equal to 6 dB down at 1.0 MHz, greater than or equal to 20 dB down at 1.2 MHz. COPYRIGHT International Telecommunications Union/ITU Radiocommunica
45、tionsLicensed by Information Handling Services122 1 .o - STD-ITU-R RECMN BT-1278-ENGL 1997 m 4855212 0533754 Ibl = Rec. ITU-R BT.1298 FIGURE 5 SSKF frequency characteristics 2.0 O O 90 180 270 360 O 90 180 270 360 (Lines per picture height) a) HoZ) 1 .o e .- v O O 90 180 270 360 (Lines per picture h
46、eight) c) qZ) 2.0 O (Lines per picture height) b) Go(Z) O 90 180 270 360 (Lines per picture height) 4 1298-05 Step 2 : Carry out the following process for VH and VT. - VH: After each line signal is compressed to one third horizontally, each three lines compressed are arrayed in one scanning line seq
47、uentially in order. The polarities of these new lines are alternately reversed from the beginning of the line, and the polarities are also reversed from the lines at the same position in the previous frame. Further, the amplitude is halved. In polarity reversing, the polarity of line No. n in the fi
48、rst field and that of line No. (n + 263) in the next field are made to be the same. In this case, positive polarity is given to the line multiplexed on the 23rd line in the first field of the reference frame (the reference frame serves as a reference phase for the helper). Reference frames occur eve
49、ry two frames. - VT: Each line signal is first compressed to one third horizontally, and the three lines are arrayed in one line sequentially in the scanning order. Step 3 : Add VH and VT after the above processing when multiplexing both of them. Step 4: The signal obtained in Step 2 or Step 3 is used to modulate the amplitude of the vertical helper subcarrier (amplitude modulation with suppressed carrier). Here, the frequency of the vertical helper subcarrier is the same as that of the colour subcarrier, and its phase is delayed by 147 from the colo
