SMPTE ST 309-2012 Transmission of Date and Time Zone Information in Binary Groups of Time and Control Code.pdf

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1、 Copyright 2012 by THE SOCIETY OF MOTION PICTURE AND TELEVISION ENGINEERS 3 Barker Avenue, White Plains, NY 10601 (914) 761-1100 Approved October 5, 2012 Table of Contents Page Foreword . 2 Intellectual Property 2 1 Scope . 3 2 Conformance Notation . 3 3 Normative References . 3 4 Glossary . 4 5 Dat

2、e and Time Zone in Binary Groups 4 5.1 Time Zone, Date Format and Daylight Saving Time in Binary Groups 7 and 8 . 4 5.2 Date as Binary Coded Decimal Digits 6 5.3 Modified Julian Date . 6 5.4 Time and Date Coordination 6 Annex A Differences between GPS Time and UTC Time (Informative) 8 Annex B Additi

3、onal Data in Binary Groups (Informative) . 9 Annex C Modified Julian Date (MJD) (Informative) . 10 Annex D Bibliography (Informative) . 11 Page 1 of 11 pages SMPTE ST 309:2012 Revision of SMPTE 309M-1999 SMPTE STANDARD Transmission of Date and Time Zone Information in Binary Groups of Time and Contr

4、ol Code SMPTE ST 309:2012 Page 2 of 11 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 conti

5、nents. SMPTEs Engineering 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-developin

6、g organizations, including ISO, IEC and ITU. SMPTE Engineering Documents are drafted in accordance with the rules given in Part XIII of its Operations Manual. SMPTE ST 309 was prepared by Technology Committee 33TS. Intellectual Property At the time of publication no notice had been received by SMPTE

7、 claiming patent rights essential to the implementation of this Standard. 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 309:201

8、2 Page 3 of 11 pages 1 Scope This standard specifies a coding technique for the transmission of date and time zone information in the user groups of a time and control code signal. A two-digit hexadecimal code in a pair of binary groups specifies the time zone and the format for the date encoding in

9、 the remaining six binary groups. Date information is encoded either as six decimal digits to display the date in the YYMMDD format or as six decimal digits in the modified Julian date (MJD) format. 2 Conformance Notation Normative text is text that describes elements of the design that are indispen

10、sable or contains the conformance language keywords: “shall“, “should“, or “may“. Informative text is text that is potentially helpful to the user, but not indispensable, and can be removed, changed, or added editorially without affecting interoperability. Informative text does not contain any confo

11、rmance keywords. All text in this document is, by default, normative, except: the Introduction, any section explicitly labeled as “Informative“ or individual paragraphs that start with “Note:” The keywords “shall“ and “shall not“ indicate requirements strictly to be followed in order to conform to t

12、he document and from which no deviation is permitted. The keywords, “should“ and “should not“ indicate that, among several possibilities, one is recommended as particularly suitable, without mentioning or excluding others; or that a certain course of action is preferred but not necessarily required;

13、 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 courses of action permissible within the limits of the document. The keyword “reserved” indicates a provision that is not defined at this time, shall

14、 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 defined in the future. A conformant implementation according to this document is one that includes all mandatory provisions (“shall“) and, if implem

15、ented, all recommended provisions (“should“) as described. A conformant implementation need not implement optional provisions (“may“) and need not implement them as described. Unless otherwise specified, the order of precedence of the types of normative information in this document shall be as follo

16、ws: Normative prose shall be the authoritative definition; Tables shall be next; followed by formal languages; then figures; and then any other language forms. 3 Normative References Note: All references in this document to other SMPTE documents use the current numbering style (e.g. SMPTE ST 12-1:20

17、08) although, during a transitional phase, the document as published (printed or PDF) may bear an older designation (such as SMPTE 12M-1-2008). Documents with the same root number (e.g. 12-1) and publication year (e.g. 2008) are functionally identical. The following standards contain provisions whic

18、h, through reference in this text, constitute provisions of this recommended practice. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this recommended practice are encouraged to investigate the possibility of a

19、pplying the most recent edition of the standards indicated below. SMPTE ST 12-1:2008, Television Time and Control Code SMPTE ST 309:2012 Page 4 of 11 pages ISO 8601:2004, Data Elements and Interchange Formats Information Interchange Representation of Dates and Times ITU-R TF.457-2 1997, Use of the M

20、odified Julian Date by the Standard Frequency and Time-Signal Services 4 Glossary Coordinated Universal Time or Universal Time, Coordinated (UTC): UTC is an international atomic time standard and is the basis for civil time. It is the current term for what was commonly referred to as Greenwich Mean

21、Time (GMT). Zero (0) hours UTC is midnight in Greenwich, England, which lies on the zero longitudinal meridian. Daylight Saving Time (DST): The civil time observed when daylight saving is adopted in a country or region. Julian Date (JD): The Julian day number is a count of days that have elapsed sin

22、ce Greenwich mean noon on 1 January 4713 B.C., Julian proleptic calendar. Modified Julian Date (MJD): The MJD is an abbreviated version of the Julian date (JD) dating method. It is defined as MJD = JD - 2400000.5. An MJD day thus begins at midnight, civil date. Standard Time: The civil time adopted

23、for a country or region. 5 Date and Time Zone in Binary Groups Two binary groups (BG7 and BG8) encode the time zone and define the format for the encoding of the date in the remaining six binary groups. The date, as specified by a date format flag bit in binary group 8, may be either six decimal dig

24、its in YYMMDD format or a six-decimal digit modified Julian date (MJD). Note: The bit positions of the binary groups are described in Table 11 of SMPTE ST 12-1 for LTC and VITC applications and in Table 6 of SMPTE ST 12-2 for ATC applications. Table 1 Date format and time zone offset coding in binar

25、y codes Binary group Assignation Description 7.0 7.1 7.2 7.3 8.0 8.1 TZ-0 TZ-1 TZ-2 TZ-3 TZ-4 TZ-5 1s bit 2s bit 4s bit Time zone code 0-63 (00-3FHEX) 8s bit see Table 2 16s bit 32s bit 8.2 DST flag 0 = DST not in effect 1 = DST in effect. 8.3 MJD flag 0 = YYMMDD format 1 = MJD (6-digit) format 5.1

26、Time Zone, Date Format and Daylight Saving Time in Binary Groups 7 and 8 Binary groups 7 and 8 as detailed in Table 1 define the format of the date encoded in binary groups 1 through 6, daylight saving time observance and the time zone (refer to Table 2). 5.1.1 MJD format flag bit If this bit is log

27、ical zero, then the date is specified as six decimal digits in the format YYMMDD (see Section 5.2). The time address represents the local clock time that has been offset from coordinated universal time SMPTE ST 309:2012 Page 5 of 11 pages (UTC) as specified by the time zone offset. If this bit is lo

28、gical one, then the date is specified as MJD encoded as six BCD digits (see Section 5.3). The time address portion of time code represents UTC without any offset. The time zone offset and daylight saving time flag are provided for information only. They may be used to calculate and display time in t

29、he local time. Note: When BCD dates are carried (MJD=0) legacy readers that are not ST 309 aware can display the correct local time and could display an intelligible date. When Modified Julian Date dates are carried (MJD=1) only readers that are ST 309 aware can decode the correct date, so to assure

30、 alignment of midnight rollover of date and time are concurrent, UTC is carried in the time bits 5.1.2 Daylight Saving Time (DST) flag bit One bit in binary group 8 is used to signal that Daylight saving time is in effect 5.1.3 Time zone coding Six bits in binary groups 7 and 8 code the local time z

31、one as defined in Table 2. Table 2 Time zone offset and time precision coding Offset Standard time (see note 2) Daylight saving Offset Standard time (see note 2) Daylight saving Code Hours Code Hours 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 UTC UTC-01:00 UTC-02:0

32、0 UTC-03:00 UTC-04:00 UTC-05:00 UTC-06:00 UTC-07:00 UTC-08:00 UTC-09:00 UTC-10:00 UTC-11:00 UTC-12:00 UTC+13:00 UTC+12:00 UTC+11:00 UTC+10:00 UTC+09:00 UTC+08:00 UTC+07:00 UTC+06:00 UTC+05:00 UTC+04:00 UTC+03:00 UTC+02:00 UTC+01:00 Greenwich Azores Mid-Atlantic Buenos Aires Halifax New York Chicago

33、Denver Los Angeles Alaska Hawaii Midway Island Kwaialein New Zealand Solomon Islands Guam Tokyo Beijing Bangkok Dhaka Islamabad Abu Dhabi Moscow Eastern Europe Central Europe Halifax New York Chicago Denver Los Angeles New Zealand Central Europe United Kingdom 0A 0B 0C 0D 0E 0F UTC-00:30 UTC-01:30 U

34、TC-02:30 UTC-03:30 UTC-04:30 UTC-05:30 Newfoundland Newfoundland 1A 1B 1C 1D 1E 1F UTC-06:30 UTC-07:30 UTC-08:30 UTC-09:30 UTC-10:30 UTC-11:30 Marquesa Islands 2A 2B 2C 2D 2E 2F UTC+11:30 UTC+10:30 UTC+09:30 UTC+08:30 UTC+07:30 UTC+06:30 3A 3B 3C 3D 3E 3F UTC+05:30 UTC+04:30 UTC+03:30 UTC+02:30 UTC+

35、01:30 UTC+00:30 32 UTC+12:45 Chatham Island 33 34 35 36 37 Undefined Undefined Undefined Undefined Undefined Reserved; do not use Reserved; do not use Reserved; do not use Reserved; do not use Reserved; do not use 26 27 Undefined Undefined Reserved; do not use Reserved; do not use 28 29 30 31 Undefi

36、ned Deprecated 38 User defined time offset 39 Undefined Unknown Unknown Notes: 1 The use of codes 28 to 31 to signal time precision information is deprecated in this revision of the standard. 2 The locations shown are informative to aid the reader. SMPTE ST 309:2012 Page 6 of 11 pages 5.1.4 Binary g

37、roup flags Binary group flag assignments conforming to the values shown in table 3 shall signal that the date and time zone are encoded using the methods described in this standard. These assignments may also signal that the time address is referenced to a precision clock time reference as described

38、 in SMPTE ST 12-1. Table 3 Binary group flag assignments for date and time zone encoded in binary groups BGF2 BGF1 BGF0 Time address reference 1 0 0 Unspecified 1 1 0 Precision Clock Note: Refer to SMPTE ST 12-1 for LTC and VITC bit numbers for 24, 25, and 30-frame-per-second systems. 5.2 Date as Bi

39、nary Coded Decimal Digits When the date in the YYMMDD format is used, the date information shall be encoded as six BCD digits in binary groups 1 to 6 as specified in Table 4. Note: If definition of the century is important, then the date can be encoded as a modified Julian date as described in Secti

40、on 5.3. 5.3 Modified Julian Date When the date in the modified Julian date format is used, the date information shall be encoded as six BCD digits in ascending order of magnitude in binary groups 1 to 6 as specified in Table 5. 5.4 Time and Date Coordination The date shall increment at the time addr

41、ess midnight rollover from 23:59:59:2x to 00:00:00:00. This implies that the date and time address are coordinated and are applicable to the local time zone or UTC, as specified by the MJD format flag and time zone offset code (see Section 5.1). SMPTE ST 309:2012 Page 7 of 11 pages Table 4 Date data

42、 in binary groups Binary group Assignation Value Description 1 2 3 4 5 6 D D M M Y Y 0-9 0-3 0-9 0, 1 0-9 0-9 Day units Day tens Month units Month tens Year units Year tens Table 5 Modified Julian date data in binary groups Binary group Assignation Value Comments 1 2 3 4 5 6 MJD units MJD tens MJD h

43、undreds MJD thousands MJD ten thousands MJD hundred thousands 0-9 0-3 0-9 0, 1 0-9 0-9 Will be zero until the year 2131 SMPTE ST 309:2012 Page 8 of 11 pages Annex A Differences between GPS Time and UTC Time (Informative) Users are cautioned to apply any necessary corrections to adjust their chosen c

44、lock reference to UTC. GPS satellite time reference signals have a known published offset from UTC and manufacturers of time code systems based on GPS signals must account for the current offset and make provisions for current and future leap second corrections. SMPTE ST 309:2012 Page 9 of 11 pages

45、Annex B Additional Data in Binary Groups (Informative) Additional data can be encoded into the binary groups by multiplexing data over several frames. When this is implemented, the binary group flags will be changed to the appropriate flag combination for the binary group encoding in use. SMPTE ST 2

46、62 describes a method using a page/line index to identify and multiplex a wide variety of data types into the binary groups. SMPTE ST 309:2012 Page 10 of 11 pages Annex C Modified Julian Date (MJD) (Informative) The modified Julian date (MJD) is an abbreviated version of the Julian date (JD) dating

47、method which has been in use by astronomers, geophysicists, chronologists, and others who need to have an unambiguous dating system based on continuing day counts. The MJD is defined as the JD minus 2400000.5. Note that JD increments at noon while MJD increments at midnight. MJD is thus a continuous

48、 count of the number of days that have elapsed since 17 November 1858. MJD is often more useful than conventional calendar dates for record keeping over long periods of time, since the MJDs of two events can easily be subtracted to determine the time difference in days. Since the MJD is a linear cou

49、nting of days, there is no requirement to differentiate between days, months, and years. As an example, the MJD for 1 January 1995 is 49718. Usually, the MJD is specified as a decimal number with five significant digits. With five digits, the count is good until the year 2132. Since this standard extends to six digits, this precludes any foreseeable problems with future date rollovers from 99,999 to 00,000. SMPTE ST 309:2012 Page 11 of 11 pages Annex D Bibliography (Informative) Note: All references in this docu