SMPTE ST 170M-2004 Television - Composite Analog Video Signal - NTSC for Studio Applications.pdf

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1、 Table of contents 1 Scope 2 Normative references 3 General description of signal 4 Input signals 5 Transfer characteristics 6 Matrixing of the signals 7 Filtering of signals 8 Subcarrier modulation 9 Timing 10 Encoded signal formulas 11 Frequency specifications 12 Video output waveform definitions

2、13 Blanking intervals and synchronizing signals 14 NTSC encoders 15 Analog interfaces Annex A Derivation of SMPTE NTSC equations Annex B IRE units Annex C Synchronizing signal timing Annex D Bibliography 1 Scope 1.1 This standard describes the composite analog color video signal for studio applicati

3、ons: NTSC, 525 lines, 59.94 fields, 2:1 interlace with an aspect ratio of 4:3. 1.2 This standard specifies the interface for analog interconnection and serves as the basis for the digital coding necessary for digital interconnection of NTSC equipment. NOTE - Parts of the NTSC signal defined in this

4、standard differ from the final report of the Second National Television System Committee (NTSC 1953) due to changes in technology and studio operating practices. 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this sta

5、ndard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent edition of the standards indicated below. Page 1 of 21 pages SMPTE 1

6、70M-2004 Revision of SMPTE 170M-1999 Copyright 2004 by THE SOCIETY OF MOTION PICTURE AND TELEVISION ENGINEERS 595 W. Hartsdale Ave., White Plains, NY 10607 (914) 761-1100 Approved November 30, 2004 SMPTE STANDARD for Television Composite Analog Video Signal NTSC for Studio Applications SMPTE 170M-20

7、04 Page 2 of 21 pages IEC 60169-8 (1978-01), Radio Frequency Connectors Part 8: R.F. Coaxial Connectors with Inner Diameter of Outer Conductor 6.5 mm (0.256 in) with Bayonet Lock Characteristic Impedance 50 Ohms (Type BNC); and Amendment 1 (1996-03) and Amendment 2 (1997-11) ISO 10526:1999 / CIE S00

8、5/E-1998, CIE Standard Illuminants for Colorimetry ISO/CIE 10527, Colorimetric Observers 3 General description of signal The composite color video signal shall contain an electrical representation of the brightness and color of a scene being analyzed (the active picture area) along defined paths (sc

9、an lines). The signal shall also include synchronizing and color reference signals that allow the geometric and colorimetric aspects of the original scene to be correctly reconstituted at the display. The synchronizing and color reference signals shall be placed in parts of the composite color video

10、 signal that are not visible on a correctly adjusted display. Certain portions of the composite color video signal that do not contain active picture information shall be blanked (forced below black level) in order to allow retrace of scanning beams in some types of cameras and display devices. 3.1

11、The video signal representing the active picture area shall consist of: a wideband luminance (brightness) component with setup (see clauses 10 and 12), and no upper bandwidth limitation for studio applications; a pair of simultaneous chrominance (coloring) components, amplitude modulated on a pair o

12、f suppressed subcarriers of identical frequency (fsc= 3.579545. MHz) in quadrature (i.e., with a 90 difference in phase). 3.2 The video signal representing the active picture area shall correspond to the scanning of the image at uniform velocities from left to right and from top to bottom. The veloc

13、ities shall be such that the picture is repetitively scanned on 525 nominally horizontal lines, with alternate lines scanned on each vertical pass. This process is described as 2:1 interlace (see clauses 11 and 13). 3.3 The aspect ratio of the active picture area shall be four units horizontally to

14、three units vertically. 3.4 The composite color video signal shall be produced by an NTSC encoder that functions as follows: 3.4.1 The input signals to an NTSC encoder shall be time-coincident green, blue, and red video signals (G B R), with no setup and of equal amplitude when conveying picture inf

15、ormation with no color content (see clause 4). Horizontal and vertical synchronizing signals and reference subcarrier shall also be required. NOTE Throughout this standard, references to signals represented by a single letter, e.g., G, B, and R, are equivalent to the nomenclature in earlier document

16、s of the form EG, EB, and ER, which, in turn, refer to signals to which the transfer characteristics given in clause 5 have been applied. Such signals are commonly described as being gamma corrected. 3.4.2 Within the encoder, the green, blue, and red (G B R) video signals shall be matrixed to form o

17、ne of two component sets, each comprising luminance (Y) and two color-difference signals (see clause 6); Y, B-Y, and R-Y or Y, I, and Q. The choice of component set is influenced by decisions regarding color component bandwidth; the final encoded signal shall be otherwise identical (see clause 7 and

18、 annex B). 3.4.3 After low-pass filtering, the color-difference signals (B-Y and R-Y or I and Q) shall be fed to balanced, quadrature-phase, subcarrier amplitude modulators. 3.4.4 The modulated subcarrier signals shall be added to the luminance signal, along with setup, blanking, sync, and burst (a

19、color synchronizing signal) to form the composite output video signal. SMPTE 170M-2004 Page 3 of 21 pages 3.5 There shall be a fixed frequency and phase relationship between the subcarrier in the burst signal, the subcarriers conveying the color-difference signals, and the horizontal and vertical sy

20、nchronizing signals (see clauses 11 and 13). 3.6 The luminance and color-difference components of the composite color video signal at the encoder output shall be time-coincident. 4 Input signals 4.1 The green, blue, and red (G B R) input signals shall be suitable for a color display device having pr

21、imary colors with the following chromaticities in the ISO/CIE 10527 system of specifications: x y Green (G) 0.310 0.595 Blue (B) 0.155 0.070 Red (R) 0.630 0.340 NOTES 1 The display primaries with the chromaticities specified above are commonly referred to as the SMPTE C set. 2 This specification doe

22、s not preclude the continued use of equipment built to the color encoding/decoding parameters of the NTSC 1953 color television transmission standard for which the chromaticities in the ISO/CIE 10527 system were specified at the following values: x y Green (G) 0.21 0.71 Blue (B) 0.14 0.08 Red (R) 0.

23、67 0.33 4.2 The system reference white is an illuminant which causes equal primary (input) signals to be produced by a reference camera and which is produced by a reference reproducer (display device) when driven by equal primary signals. For this system, the reference white is specified in terms of

24、 its ISO/CIE 10527 chromaticity coordinates, which have been chosen to match those of ISO 10526 / CIE S005/E illuminant D65: x = 0.3127 y = 0.3290 4.3 The input signals shall have no setup. Their amplitudes shall be equal for picture areas whose chromaticity corresponds to the system reference white

25、. System nominal peak white shall be represented by input signals whose amplitudes are 100 IRE units for G, B, and R. NOTE IRE units are a linear scale for measuring the relative amplitudes of signals. An IRE unit has no absolute value, unless defined (see annex B). 5 Transfer characteristics The re

26、ference reproducer for this system is representative of cathode ray tube displays, which have an inherently nonlinear electro-optical transfer characteristic. To achieve an overall system transfer characteristic that is linear, it is necessary to specify compensating non-linearity elsewhere in the s

27、ystem. In the NTSC system, this is done at the signal source. For purposes of precision, particularly in digital signal processing applications, exactly inverse characteristics are specified for the reference camera and reproducer. The respective transfer characteristics shall be as defined in 5.1 a

28、nd 5.2. It is recognized that operating values may vary from the precise values given in order to meet operational requirements in practical systems. SMPTE 170M-2004 Page 4 of 21 pages 5.1 Opto-electronic transfer characteristic of reference camera VC= 1.099 LC(0.4500) 0.099 for 0.018 LC 1 VC= 4.500

29、 LCfor 0 LC 0.018 where VCis the video signal output of the reference camera, normalized to the system reference white, and LCis the light input to the reference camera, normalized to the system reference white. 5.2 Electro-optical transfer characteristic of reference reproducer LT= (Vr+ 0.099)/1.09

30、9(1/0.4500) for 0.0812 Vr 1 LT= Vr/4.500 for 0 Vr 0.0812 where Vris the video signal level driving the reference reproducer, normalized to the system reference white, and LTis the light output from the reference reproducer, normalized to the system reference white. NOTE The description above is a mo

31、re technically correct definition of the transfer function (gamma correction), particularly in dark areas of the picture, than the form used in older documents, viz., having a transfer gradient (gamma exponent) of 2.2 associated with each primary and signals shall be gamma corrected through applicat

32、ion of an exponential transfer gradient inverse to that assumed in the display; i.e., 1/2.2 (0.455.). 6 Matrixing of the signals The green, blue, and red (G B R) video signals shall be matrixed to form one of two baseband component sets of luminance (Y) and two color-difference signals: Y, B-Y, and

33、R-Y or Y, I, and Q. 6.1 Luminance (Y) and the color-difference signals B-Y and R-Y can be matrixed from G, B, and R according to the following formulas: Y = + 0.587G + 0.114B + 0.299R BASE EQUATION B-Y = 0.587G + 0.886B 0.299R R-Y = 0.587G 0.114B + 0.701R 6.2 The color-difference signals I and Q can

34、 be matrixed from color-difference signals B-Y and R-Y according to the following formulas: I = 0.2680. (B-Y) + 0.7358. (R-Y) Q = + 0.4127. (B-Y) + 0.4778. (R-Y) (.approximate values) 6.3 The color-difference signals I and Q can also be directly matrixed from G, B, and R video signals according to t

35、he following formulas: I = 0.2746. G 0.3213. B + 0.5959. R Q = 0.5227. G + 0.3112. B + 0.2115. R (.approximate values) NOTE This standard assumes input signals (G B R) to the encoder without setup. The luminance signal (Y) generated by the luminance equation above is, therefore, also without setup.

36、Adjustment to achieve the required luminance signal, including setup, is performed in the encoding equations defined in clause 10. It should be noted that this practice differs from the NTSC 1953 specification, which utilized input signals to the encoder having setup on them and, hence, not requirin

37、g the addition of setup in the encoder. It should also be noted that the coefficients given for G, B, and R in the luminance base equation are precise values; i.e., 0.587 G = 587/1000 G, etc. SMPTE 170M-2004 Page 5 of 21 pages 7 Filtering of signals 7.1 This standard does not impose a bandwidth rest

38、riction on the luminance part of the NTSC signal. Care should be taken to ensure that appropriate filtering is applied before the signal is fed to bandwidth-limited devices. 7.2 The color-difference signals shall be bandwidth limited prior to modulation as follows: less than 2 db down at 1.3 MHz; at

39、 least 20 db down at 3.6 MHz. (See figure 1 for an example of the baseband, modulated carrier, and encoded composite signal passbands.) 7.3 The low-pass filters that are used with the baseband color-difference signals should have characteristics with a minimum of ringing and overshoot (Gaussian filt

40、er characteristics, for example). NOTE to clause 7 This standard does not preclude the continued use of equipment built to the NTSC 1953 color television transmission standard for which the I signal bandwidth is as specified in 7.2 and the Q signal bandwidth is limited as follows: at 0.4 MHz less th

41、an 2 db down; at 0.5 MHz less than 6 db down; at 0.6 MHz at least 6 db down. When the overall bandwidth is not limited to less than 5 MHz, use of wideband, equiband chroma signals provides improved chroma resolution for signal processing in the studio. When the composite NTSC signal is transmitted (

42、or recorded on some types of video tape recorders), the overall bandwidth is normally limited to less than 5 MHz, typically 4.2 MHz as for broadcasting. In such cases, if it is desired to permit recovery at the receiver of the wideband I signal, as provided in the NTSC transmission specifications, i

43、t is necessary to decode and re-encode with the appropriate narrowband Q channel filter prior to transmission (or ecording). (See SMPTE EG 27 for further information.) This standard does not preclude the application of more sophisticated filtering techniques to any combination of the luminance, colo

44、r-difference, or chrominance signals, provided care is taken not to degrade picture quality on display devices not equipped for operation with the sophisticated filtering techniques. 8 Subcarrier modulation 8.1 After low-pass filtering, the B-Y and R-Y (or I and Q) signals shall be fed to balanced,

45、quadrature-phase, subcarrier amplitude modulators. This process yields suppressed-carrier amplitude modulation in which the subcarrier chrominance signals (chroma) reduce to zero when the G B R input signals are of equal amplitude. 8.2 A gated and filtered signal derived from subcarrier, called the

46、burst, shall be added in the horizontal blanking interval of each line, excluding the nine-line vertical sync interval, as a synchronizing signal and amplitude reference for the chrominance signals. The burst signal shall be inverted in phase from the reference subcarrier. 8.3 The modulated subcarri

47、er signals (B-Y and R-Y or I and Q) shall be added to the luminance signal along with sync, blanking, setup, and burst to form the composite output video signal (N). 9 Timing The input signals to the encoder shall be time coincident. Similarly, all the components that make up the encoded composite v

48、ideo signal (N) shall be time coincident at the output of the encoder (see figure 2). The recommended tolerance for time coincidence shall be 25 ns for any pair of nominally coincident signals. SMPTE 170M-2004 Page 6 of 21 pages Figure 1 Examples of signal passbands SMPTE 170M-2004 Page 7 of 21 page

49、s Figure 2 Points of time coincidence Figure 3 Chrominance axis and burst phase 10 Encoded signal formulas The encoded video signal (N), without sync, burst, and blanking, shall be defined by the following formulas (see figure 3). (These equations assume G B R inputs to the encoder of 100 IRE without setup). Where Y, B-Y, and R-Y are used: N = 0.925(Y) + 7.5 + 0.4552.(B-Y) sin(2fsct) + 0.8115.(R-Y) cos (2fsct) BASE EQUATION or, where Y, I, and Q are used: N = 0.925(Y) + 7.5 + 0.92