ANSI SMPTE ST 253M-1998 Television - Three-Channel RGB Analog Video Interface.pdf

1、STD-SMPTE 235fl-ENGL 1778 8357LiOL 0002987 102 m SMPTE STANDARD for Television - Three-C hannel RGB Analog Video Interface ANWSMPTE 253M-1998 1 Scope This standard defines the component analog video interface for studio applications using three primary color signals carried on parallel channels for

2、the inter- connection of television equipment. The signals carried across the interface have a typical scanning structure of 525 lines, 59.94 fieldsls, 2:l interlace, and 4:3 or 16:9 aspect ratio. The signals have a vertical blanking interval that is divided into an active line period and a horizont

3、al blanking interval. Signal characteristics are defined by a gamma-corrected set of red, green, and blue RGB (hereafter defined as RGB) primary video signals. In addition to general interconnection of television equipment at the RGB component analog level of operation, the signals defined by this s

4、tandard are suitable as inputs to analog-to-digital conversion systems in compliance with ANSVSMPTE 125M and ANSVSMPTE 267M or as inputs to NTSC composite encoders in compliance with ANSVSMPTE 170M. The three-channel interface defined by this standard (sync on green) is the preferred implementation.

5、 Some applications may require a four-channel inter- face (with sync carried separately). Such an imple- mentation is described in annex A. 2 Normative reference The following standard contains provisions which, through reference in this text, constitute provisions of this standard. At the time of p

6、ublication, the edition indicated was valid. All standards are subject to revision, and parties to agreements based on this standard are encouraged to investigate the possibility Page 1 of 7 pages of applying the most recent edition of the standard indicated below. IEC 60169-8 (1978-Ol), Part 8: R.F

7、. Coaxial Con- nectors with Inner Diameter of Outer Conductor 6.5 mm (0.256 in) with Bayonet Lock- Characteristic Impedance 50 Ohms (Type BNC); Appendix A (1993), Information for Interface Dimensions of 75- Ohm Characteristic Impedance Connectors with Unspecified Reflection Factors; and Amendment NO

8、. 1 (1996-03) 3 Scanning 3.1 The video signal shall correspond to scanning of the image at uniform velocities from left to right and from top to bottom. This will provide 525 nominally horizontal lines where alternate lines are scanned on each vertical pass for 2:l interlace. As a result of vertical

9、 blanking, there are 483 active picture lines which are divided into an active picture period and a horizontal blanking period. 3.2 The aspect ratio of the active picture is entirely determined by the geometry of the pickup and display devices which should be appropriately matched. Parameters specif

10、ied in this standard are not affected by the operational aspect ratio. Typical aspect ratios are 4:3 and 16:9. 4 System colorimetry 4.1 The RGB signals shall be suitable for a color display device having primary colors with the following chromaticities in the CIE SOO2 system of specifications: CAUTI

11、ON NOTICE This Standard may be revised or withdrawn at any time The procedures of the Standard Developer require that action be taken to reaffirm, revise. or withdraw this standard no later than five years from the date of publication Purchasers of standards may receive current information on all st

12、andards by calling or writing the Standard Developer Printed in USA American Nalional Standard Copyright G 1998 by THE SOCIETY OF MOTION PICTURE AND TELEVISION ENGINEERS 595 W Harbdaie Ave., White Plains. NY 10607 (914) 761-1100 Approved March 3, 1998 7 STD-SMPTE 235M-ENGL 1778 8357iOL 0002988 OLi9

13、H ANSIISMPTE 253M-1998 X Y Red (R) 0.630 0.340 Green (G) 0.310 0.595 Blue (B) 0.155 0.070 NOTES 1 The display primaries with the chromaticities specified above are commonly referred to as the SMPTE C set. 2 This specification does not preclude the continued use of equipment built to the color parame

14、ters of the NTSC 1953 color television transmission standard for which the chro- maticities in the CIE SO02 system were specified at the values listed below. Signals produced using the original NTSC specifications will not display properly on modern display devices: X Y Red (R) 0.67 0.33 Green (G) 0

15、.21 0.71 Blue (B) 0.14 0.08 4.2 The system reference white is an illuminant which causes equal primary signals to be produced by a reference camera and which is reproduced by a reference display device when driven by equal primary signals. For this system, the reference white is specified in terms o

16、f its CIE SO02 chromaticity coordinates which have been chosen to match those of CIE SO02 illumi- nant D65: x = 0.3127 y= 0.3290 4.3 The individual component amplitudes shall be equal for picture areas whose chromaticity corresponds to the system reference white. 5 Transfer characteristics 5.1 The r

17、eference reproducer for this system is representative of cathode ray tube displays, which have an inherently nonlinear electro-optical transfer characteristic (see annex B). To achieve an overall system transfer characteristic that is linear, it is necessary to specify compensating nonlinearity else

18、where in the system. This is done at the signal source. For purposes of pre- cision, particularly in digital signal processing applications, exactly inverse characteristics are specified for the reference camera and repro- ducer. The respective transfer characteristics as defined in 5.1.1 and 5.2 sh

19、all be applied to all three channels. It is recognized that operating values may vary from the precise values given in order to meet operational requirements in practical systems. 5.1.1 Electro-optical transfer characteristic of the reference camera shall be: vc = 1 .o99 x Lc Vc = 4.500 x Lc for O 5

20、 LC 5 0.018 - 0.099 for 0.01 8 5 Lc 5 1 where Vc is the video signal output of the reference camera normalized to the system reference white and Lc is the light input to the reference camera normal- zed to system reference white. 5.2 Electro-optical transfer characteristic of the reference reproduce

21、r shall be: LT = (Vr + 0.099)/1 .099(“0.4500) for 0.081 2 5 Vr 5 1 LT = 4.500 x LC for O 5 Vr 5 0.0812 where Vr is the video signal level driving the reference reproducer normalized to the system reference white and LT is the light output from the reference repro- ducer normalized to system referenc

22、e white. 6 RGB component set The RGB component set, as shown in figure 1, origi- nates as equiband and garnrna-corrected (see clause 5) RGB primary signals from a picture source, such as a camera or telecine, or as synthetically generated RGB video from a character generator, graphics generator, or

23、test signal generator. These video signals are positive going, and each shall have a maximum peak level of 700 mV from blanking level with zero setup. The green signal shall have a negative-going sync pulse of amplitude 300 mV from blanking level that conforms to the timing require- ments of clause

24、7. NOTES 1 Some applications may require a four-channel inter- face (with sync carried separately). Such an implemen- tation is described in annex A. Page 2 of 7 pages STD-SMPTE 235M-ENGL 1778 8357LiOL 0002787 T5 ANSI/SMPTE 253M-1998 mV +7001- - - - - GREEN u00 O i! - rnV rnV Figure 1 - RGB componen

25、t set 2 Some applications may require sync on all of the three component channels. In that case, waveform specifications for the synchronizing area of the red and blue signals will be identical to those of the green signal. Such an implemen- tation is not described further in this standard. 7 Horizo

26、ntal blanking and synchronization Each line outside the vertical blanking interval is divided into an active line period and a horizontal blanking interval. The horizontal blanking interval for the green signal contains the negative-going horizontal sync pulse. The remainder of the horizontal blanki

27、ng interval is at blanking level and may be used for signal dc clamping. Horizontal timing is given in table 1 and shown in figure 2. 8 Vertical blanking and synchronization In an interlaced raster, each television frame (one complete scanning of the picture) is divided into two fields. The fields c

28、arry every other scan line in succes- sion with succeeding fields carrying the lines not scanned by the previous field. Each field is divided into an active picture area and a vertical blanking interval. The vertical blanking interval for the green signal contains the vertical synchronizing informat

29、ion surrounded by blanking periods to prop- erly position the vertical sync and by space allocated for special vertical interval signals (equalizing pulses) as shown in figure 3 (optional separate sync is also shown in annex A). Page 3 of 7 pages STD-SMPTE 235M-ENGL 1998 8357403 0002977 7T7 D ANCI/C

30、MPTE 253M-1998 Table 1 - Video signal horizontal timing Measurement Recommended points Value tolerance Units PS Total line period (derived) 63.556 Horizontal blanking rise time 10% - 90% 140 i 20 ns Sync rise time 10% - 90% 140 i 20 ns H-blanking start to H-reference 5 0 O/o 1.3 i 0.1 PS Horizontal

31、sync 5 0 O/o 4.7 IO.1 PS H-reference to H-blanking end 50% 9.0 PS + 0.2 - 0.1 NOTE - It is recognized that horizontal blanking operating values may vary from the precise values given in order to meet operational requirements in practical systems and to ensure that an encoded output sianal meets that

32、 in ANSIISMPTE 170M (M/NTSC). H Blanking rise time 50% - 50% - to H reference - Sync .F H reference to Blanking End 4 Figure 2 - Horizontal blanking interval, green signal c Page 4 of 7 pages STD-SMPTE 235M-ENGL 1998 ANSVSMPTE 253M-1998 The vertical synchronization signal consists of a nine- line bl

33、ock divided into three, three line long segments. The first segment contains six preequalizing pulses. The second segment contains the vertical synchronizing pulse with six serrations provided to maintain horizontal synchronization. The third segment contains six post- equalizing pulses. The remaind

34、er of the vertical blanking interval not used for the nine-line vertical sync block is available for special vertical interval signals. When such signals are carried on a particular line, the signals must conform to the period between horizontal blanking intervals. When such signals are not carried

35、on a particular line, the line must be maintained at blanking level. 9 Interface characteristics 9.1 Each of the three signals shall be carried on an unbalanced coaxial cable whose nominal impedance is 75 ohms. Preferred channel numbering is Chl = green, Ch2 = blue, Ch3 = red. NOTE - In color-differ

36、ence systems not covered by this standard, Chl = luminance, Ch2 = PE, Ch3 = PR. 9.2 Signal sources shall have an unbalanced output circuit with a source impedance of 75 ohms and a return loss of at least 30 dB over a frequency range of 1 kHz to the maximum of the frequency range used. 9.3 Signal amp

37、litudes shall conform to clauses 4, 5, and 6. 9.4 Any pair of signals in the set shall be time coincident with respect to each other Ir 5 ns when used in a totally component system. When used as the input to an encoder, all signals shall be time coincident with respect to encoder out- put sync, with

38、 adjustments for encoder internal delays. 9.5 The dc offset, as defined by the blanking level of the signal, shall be 0.0 V f 1 .O V. 9.6 The terminating impedance of a receiver signal shall be 75 ohms with a return loss of at least 30 dB over a frequency range of 1 kHz to the maxi- mum of the frequ

39、ency range used. Table 2 - Video signal vertical timing Measurement Recommended points Value tolerance Units Field period (derived) 16.6833 ms Frame period (derived) 33.3667 ms Vertical blanking start before Vertical blanking 20 lines) O) lines first equalizing pulse 5 0 O/o 1.5 5 0.1 PS (63.556 s x

40、 20 lines + 1.5 s) (approximate value, see notes) 1.5 ps IO.1 PS Preequalizing pulse width 5 0 10 2.3 * 0.1 PS Vertical serration pulse width 50% 4.7 * 0.1 PS Post-equalizing pulse width 50% 2.3 f 0.1 KS plus Preequalizing duration 3 lines Vertical sync duration 3 lines Post-equalizing duration 3 li

41、nes NOTES 1 Some component equipment does not blank lines 20 and 282, resulting in 19-line (I 1.5 ps) vertical blanking. 2 All pulse rise and fall times, unless otherwise specified, are to be 140 ns * 20 ns measured from 10% to 90% amplitude points. All pulses are measured at 50% amplitude points. P

42、age 5 of 7 pages STD-SMPTE 235M-ENGL 1798 8357q03 0002792 57T U ANWSMPTE 253M-1998 Vertical Blanking Interval 21234567891011 yl2d 119y20y21 1 GREEN Start of Field I Pre-equalizing Dulse interval -i Start of Field 2 A . p2y1 -t-23-t-4-t-5-t-678910y11 y121 t19j+20?211 I I (optional) (see Annex A) SYNC

43、 I Figure 3 - Vertical blanking interval Page 6 of 7 pages STD-SMPTE 235M-ENGL 1778 = 8357901 0002993 iOb D 9.7 The connector shall have mechanical char- acteristics conforming to the 50-ohm BNC type. Mechanical dimensions of the connector may produce either a nominal 50-ohm or nominal Annex A (info

44、rmative) Implementation using four channels In some applications, it may be necessary to implement systems using four separate channels rather than the three channels specified in the main body of this standard. Although the three-channel implementation is the preferred method, a four-channel approa

45、ch is provided as defined in this annex. In a four-channel interface, the fourth channel is used to carry the synchronizing signal. The first three channels are used to carry the RGB component signal set. These are identical to the signals used in the three-channel implemen- tation with the exceptio

46、n that sync need not be added to the Annex B (informative) Reference camera and reproducer In clause 5, the electro-optical transfer characteristics of the reference camera and reproducer are defined. These references do not represent the transfer characteristics of real devices; rather, they are ma

47、thematical descriptions of a transfer function, the reproducer being the inverse of the camera leading to a linear system that is convenient for many analyses. Experience has shown that, for the most Annex C (informative) ANSIBMPTE 170M (NTSC) encoders ANSIISMPTE 170M requires an input signal of 714

48、 mV, not the 700 mV of this standard. However, most system M/NTSC encoders have input gain adjustments. Even if the encoder Annex D (informative) Bibliography ANSIISMPTE 125M-1995, Television - Component Video Signal 4:2:2 - Bit-Parallel Digital Interface ANSVSMPTE 170M-1994, Television - Composite

49、Analog Video Signal - NTSC for Studio Applications ANSVSMPTE 267M-1995, Television - Bit Parallel Digital Interface - Component Video Signal 4:2:2 16x9 Aspect Ratio ANSVSMPTE 253M-1998 75-ohm impedance. Where a 75-ohm connector is used, its mechanical characteristics must reli- ably interface with the nominal 50-ohm BNC type defined by IEC 60169-8. green signal. Although sync is not required on any of the video signals, it is not precluded, and system designers are advised to allow for the possibility that sync will appear on one or all of the video signals.