SMPTE ST 12-1-2014 Time and Control Code.pdf

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1、 Copyright 2014 by THE SOCIETY OF MOTION PICTURE AND TELEVISION ENGINEERS 3 Barker Avenue, White Plains, NY 10601 (914) 761-1100 Approved February 20, 2014 ( Table of Contents Page Foreword . 4 Intellectual Property 4 Introduction 5 1 Scope 6 2 Conformance Notation 6 3 Normative References 7 4 Defin

2、itions . 7 4.1 Time and Control Code . 7 4.2 Linear Time Code (LTC) . 7 4.3 Vertical Interval Time Code (VITC) . 8 4.4 Ancillary Time Code (ATC) . 8 4.5 Frame 8 4.6 Field 8 4.7 Time Code Source/Original Source 8 4.8 Binary Coded Decimal (BCD) System 8 4.9 Frame Rate . 8 4.10 Frame Pair. 8 5 Time Rep

3、resentation in 30 and 60 Frames-Per-Second Systems . 9 5.1 Definitions of Real Time and NTSC Time . 9 5.1.1 Definition of real time 9 5.1.2 Definition of NTSC time 9 5.2 Time Address of a Frame . 9 5.2.1 Non-drop frame Uncompensated mode 9 5.2.2 Drop frame NTSC time compensated mode . 9 5.3 Color Fr

4、ame Identification in NTSC Analog Composite Television Systems . 10 6 Time Representation in 25 and 50 Frames-Per-Second Systems . 10 6.1 Definition of Real Time 10 6.2 Time Address of a Frame . 10 6.3 Color Frame Identification in PAL Composite Television Systems . 10 6.3.1 Logical relationship. 11

5、 6.3.2 Arithmetic relationship 11 7 Time Representation in 24 and 48 Frames-Per-Second Systems . 11 7.1 Definitions of Real Time and NTSC Time . 11 7.1.1 Definition of real time 11 7.1.2 Definition of NTSC time 11 7.2 Time Address of a Frame . 12 Page 1 of 41 pages SMPTE ST 12-1:2014 Revision of SMP

6、TE 12M-1:2008 SMPTE STANDARD Time and Control Code SMPTE ST 12-1:2014 Page 2 of 41 pages 8 Structure of the Time Address and Control Bits 12 8.1 Numeric Code 12 8.2 Time Address. 12 8.3 Flag Bits . 12 8.3.1 Drop frame flag . 12 8.3.2 Color frame flag (NTSC and PAL composite color systems) . 12 8.3.3

7、 Binary group flags . 12 8.3.4 Modulation method specific flag . 13 8.4 Use of the Binary Groups 13 8.4.1 Character set not specified and unspecified clock time (BGF2=0, BGF1=0, BGF0=0) . 13 8.4.2 Eight-bit character set and unspecified clock time (BGF2=0, BGF1=0, BGF0=1) . 13 8.4.3 Character set no

8、t specified and clock time specified (BGF2=0, BGF1=1, BGF0=0) . 14 8.4.4 Reserved binary group usage and reserved clock time (BGF2=0, BGF1=1, BGF0=1) . 14 8.4.5 Date/time zone and unspecified clock time (BGF2=1, BGF1=0, BGF0=0) 14 8.4.6 Page/line multiplex system and unspecified clock time (BGF2=1,

9、BGF1=0, BGF0=1) . 14 8.4.7 Date/time zone and clock time (BGF2=1, BGF1=1, BGF0=0) . 14 8.4.8 Page/line multiplex system and clock time specified (BGF2=1, BGF1=1, BGF0=1) . 14 8.5 Clock Time Reference Binary Group Flag Combinations 14 9 Linear Time Code Application . 14 9.1 Codeword Format 14 9.2 Cod

10、eword Data Content 15 9.2.1 Time address 15 9.2.2 Flag bits 15 9.2.3 Biphase mark polarity correction 15 9.2.4 Binary groups 16 9.2.5 Synchronization word . 16 9.3 Modulation Method 17 9.4 Bit Rate 17 9.5 Timing of the Codeword Relative to a Television Signal . 18 9.6 Linear Time Code Interface Elec

11、trical and Mechanical Characteristics 18 9.6.1 Rise/fall time . 18 9.6.2 Amplitude distortion 18 9.6.3 Timing of the transitions 18 9.6.4 Interface connector (Informative) . 19 9.6.5 Output impedance 19 9.6.6 Output amplitude (Informative) 19 10 Vertical Interval Application Analog Television System

12、s 24 10.1 Codeword Format . 24 10.2 Codeword Data Content . 24 10.2.1 Time address 27 10.2.2 Flag bits 27 10.2.3 Binary groups 27 10.2.4 Field identification flag 28 10.2.5 Synchronization bits 28 10.2.6 Cyclic redundancy check code . 28 10.3 Modulation Method . 29 10.4 Bit Timing 29 10.5 Timing of

13、the Codeword Relative to the Television Signal . 29 10.5.1 525/59.94 television system . 29 10.5.2 625/50 television system 29 10.6 Location of the VITC Codeword in the Vertical Interval . 30 10.6.1 525/59.94 television system . 30 10.6.2 625/50 television system 30 10.6.3 Component television syste

14、ms . 30 10.7 Redundancy 30 SMPTE ST 12-1:2014 Page 3 of 41 pages 10.8 Vertical Interval Time Code Waveform Characteristics . 30 10.8.1 Logic level . 30 10.8.2 Rise/fall time 31 10.8.3 Amplitude distortion . 31 11 Relationship Between LTC and VITC . 31 11.1 Time Address Data 31 11.2 Binary Group Data

15、 . 31 11.2.1 Transferring VITC binary group data to LTC binary group data . 31 11.2.2 Transferring LTC binary group data to VITC binary group data . 31 11.3 VITC and LTC Codeword Comparison 31 12 Progressive Systems with Frame Rates Greater than 30 Frames Per Second . 33 12.1 Time Address of a Frame

16、 Pair in 48, 50, and 60 Frames-Per-Second Progressive Systems . 33 12.2 Implementation Guidelines (Informative) 34 Annex A Explanatory Notes (Informative) . 35 A.1 Time Precision 35 A.2 Leap Second Corrections . 35 A.3 Frames and Time Code 35 Annex B Converting Time Codes when Converting Video from

17、24 Frames-Per-Second Television Systems (Informative) 37 B.1 Conversion of 24/1.001 (23.98) Fps Video to 30/1.001 (29.97) Fps Video 37 B.2 Conversion of 24 Fps Video to 25 Fps Video . 38 Annex C Bibliography (Informative) . 39 Annex D Time Code System “Roadmap“ (Informative) . 41 SMPTE ST 12-1:2014

18、Page 4 of 41 pages Foreword SMPTE (the Society of Motion Picture and Television Engineers) is an internationally-recognized standards developing organization. Headquartered and incorporated in the United States of America, SMPTE has members in over 80 countries on six continents. SMPTEs Engineering

19、Documents, including Standards, Recommended Practices and Engineering Guidelines, are prepared by SMPTEs Technology Committees. Participation in these Committees is open to all with a bona fide interest in their work. SMPTE cooperates closely with other standards-developing organizations, including

20、ISO, IEC and ITU. SMPTE Engineering Documents are drafted in accordance with the rules given in its Standards Operations Manual. SMPTE Standard ST 12-1 was prepared by Technology Committee 33TS. Intellectual Property At the time of publication no notice had been received by SMPTE claiming patent rig

21、hts essential to the implementation of this Engineering Document. However, attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. SMPTE shall not be held responsible for identifying any or all such patent rights. SMPTE ST 12-1:2014 Page

22、5 of 41 pages Introduction This section is entirely informative and does not form an integral part of this document. This standard is one of the oldest SMPTE Standards. It was first adopted in 1975, and it has been widely used for many systems outside SMPTEs normal area of purview. It was developed

23、for analog television recording systems and thus dealt only with interlaced television systems operating with frame rates up to 30 frames per second. It is, however, flexible enough in design to be used in digital television systems, both standard definition and high definition. The actual transport

24、 of the codewords for digital systems varies significantly from the transport methods defined for analog systems, and is defined in the associated document, SMPTE ST 12-2. Progressive video systems with frame rates above 30 frames per second are described in this document, documenting what have beco

25、me “de facto” implementations. Since the frame rate of these 50 and 60 frames- per-second progressive systems exceeds the frame count capacity of the time address, counting is done on frame pairs, which results in an edit resolution of two frames using traditional linear time code. For applications

26、of time code to film, SMPTE Recommended Practices RP 135 and RP 136 (see Annex C, Bibliography), which are similar to, but not the same as this standard, may be applied, in particular for in-camera optical recording. Sections 5, 6, and 7 specify the manner in which time is represented in frame-based

27、 systems. Section 8 describes the structure of the time address and control bits of the code, and sets guidelines for storage of user data in the binary groups of the code. Section 9 specifies the modulation method and interface characteristics of a linear time code (LTC) source. Section 10 specifie

28、s the modulation method for inserting the code into the vertical interval of an analog television signal (VITC). Section 11 summarizes the relationship between the two forms of time and control code, LTC and VITC. Section 12 has been added to document time code implementations for video formats with

29、 frame per second rates greater than 30 fps. The readers attention is drawn to the following documentation changes from the prior SMPTE 12M:1999: Two SMPTE Recommended Practices RP 164:1996, Location of Vertical Interval Time Code, and RP 159:1995, Vertical Interval Time Code and Longitudinal Time C

30、ode Relationship have been consolidated into this document. The LTC reference datum has been relocated to the beginning of Vertical Sync from a location one horizontal line later. This change includes a widening of the tolerance interval to include the previous location tolerance interval The time c

31、ode documents have been restructured and organized into a suite of documents: SMPTE ST 12-1 (previously SMPTE 12M), including the revisions described above. SMPTE ST 12-2 (previously SMPTE RP 188), Ancillary Time Code. SMPTE ST 12-1:2014 Page 6 of 41 pages 1 Scope This Standard specifies a time and

32、control code for use in television and accompanying audio systems operating at nominal rates1 of 60, 59.94, 50, 48, 47.95, 30, 29.97, 25, 24, and 23.98 frames per second. This standard defines a time address, binary groups, and flag bit structure. The standard also defines a binary group flag assign

33、ment, a linear time code transport, and a vertical interval time code transport. This standard defines primary data transport structures for Linear Time Code (LTC) and Vertical Interval Time Code (VITC). This standard defines the LTC modulation and timing for all video formats. This standard also de

34、fines the VITC modulation and location for 525/59.94 and 625/50 analog composite and component systems only. Note: The digital representation of analog VITC (D-VITC) is specified in SMPTE ST 266 and is defined for 525/59.94 and 625/50 digital component systems only. High Definition formats, such as

35、those documented in SMPTE ST 2048-2, SMPTE ST 274, and SMPTE ST 296, use Ancillary Time Code (ATC) as specified in SMPTE ST 12-2 (formerly SMPTE RP 188) for transport of time code in the digital video data stream. For future implementations of time code for digital Standard Definition formats, the u

36、se of ATC rather than D-VITC is encouraged. 2 Conformance Notation Normative text is text that describes elements of the design that are indispensable or contains the conformance language keywords: “shall“, “should“, or “may“. Informative text is text that is potentially helpful to the user, but not

37、 indispensable, and can be removed, changed, or added editorially without affecting interoperability. Informative text does not contain any conformance keywords. All text in this document is, by default, normative, except: the Introduction, any section explicitly labeled as “Informative“ or individu

38、al paragraphs that start with “Note:” The keywords “shall“ and “shall not“ indicate requirements strictly to be followed in order to conform to the document and from which no deviation is permitted. The keywords, “should“ and “should not“ indicate that, among several possibilities, one is recommende

39、d as particularly suitable, without mentioning or excluding others; or that a certain course of action is preferred but not necessarily required; or that (in the negative form) a certain possibility or course of action is deprecated but not prohibited. The keywords “may“ and “need not“ indicate cour

40、ses of action permissible within the limits of the document. The keyword “reserved” indicates a provision that is not defined at this time, shall not be used, and may be defined in the future. The keyword “forbidden” indicates “reserved” and in addition indicates that the provision will never be def

41、ined in the future. A conformant implementation according to this document is one that includes all mandatory provisions (“shall“) and, if implemented, all recommended provisions (“should“) as described. A conformant implementation need not implement optional provisions (“may“) and need not implemen

42、t them as described. 1The reader is cautioned that non-integer values are abbreviated. These abbreviations may be seen throughout this document. See Section 5.1.2 for additional information. SMPTE ST 12-1:2014 Page 7 of 41 pages 3 Normative References Note: All references in this document to other S

43、MPTE documents use the current numbering style (e.g. SMPTE ST 170:2004) although, during a transitional phase, the document as published (printed or PDF) may bear an older designation (such as SMPTE 170M-2004). Documents with the same root number (e.g. 170) and publication year (e.g. 2004) are funct

44、ionally identical. The following standards contain provisions which, through reference in this text, constitute provisions of this standard. 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 enco

45、uraged to investigate the possibility of applying the most recent edition of the standards indicated below. ISO/IEC 646:1991, Information Technology ISO 7-Bit Coded Character Set for Information Interchange ISO/IEC 2022:1994, Information Technology Character Code Structure and Extension Techniques R

46、ecommendation ITU-R BT.1700 (2005), Characteristics of Composite Video Signals for Conventional Analogue Television Systems, Annex 1 Part B, PAL Signal Format and Specification SMPTE ST 170:2004 (Archived 2010), Television Composite Analog Video Signal NTSC for Studio Applications SMPTE ST 262:1995

47、(Archived 2011), Television, Audio and Film Binary Groups of Time and Control Codes Storage and Transmission of Data SMPTE ST 309:2012, Transmission of Date and Time Zone Information in Binary Groups of Time and Control Code SMPTE RP 168:2009, Definition of Vertical Interval Switching Point for Sync

48、hronous Video Switching 4 Definitions 4.1 Time and Control Code The term “time and control code” encompasses all aspects of the time address, flag bits, and binary groups for user-defined data codes, as well as two methods of modulation of the resulting codewords. It is commonly abbreviated to simpl

49、y “time code” (note that some users spell this “timecode”). Note: The time address and binary group (“user data”) payload is attached to a particular frame or frame pairs either directly or by reference within the users system. For frame-based systems the time address that forms part of the time code is primarily intended as a label to identify discrete frames. It also may imply that a particular frame has had, has now, or will have, a tempor