1、 Copyright 2015 by THE SOCIETY OF MOTION PICTURE AND TELEVISION ENGINEERS 3 Barker Avenue, White Plains, NY 10601 (914) 761-1100 Approved March 26, 2015 Table of Contents Page Foreword . 2 Intellectual Property 2 Introduction 2 1 Scope . 4 2 Conformance Notation . 4 3 Normative References . 4 4 Defi
2、nition of Terms and Acronyms . 5 5 PTP Profile . 6 5.1 Profile Identification 6 5.2 Best Master Clock Algorithm (BMCA) 6 5.3 Management Mechanism . 7 5.4 Path Delay Measurement Mechanism . 7 5.5 PTP Attribute Values 7 5.6 Slave Clocks 10 5.7 Clock Physical Requirements 10 5.8 Node Types Required, Pe
3、rmitted or Prohibited . 10 5.9 Transport Mechanisms Permitted 11 5.10 Communication Model . 11 5.11 PTP Options . 11 5.12 Alternate Master . 11 5.13 Organization Extension TLV: Synchronization Metadata 12 5.14 Setting Dynamic SM TLV Values . 15 Annex A Calculation of timeOfNextJam (Normative) . 18 A
4、nnex B Bibliography (Informative) . 19 SMPTE ST 2059-2:2015 Page 1 of 19 pages SMPTE STANDARD SMPTE Profile for Use of IEEE-1588 Precision Time Protocol in Professional Broadcast Applications SMPTE ST 2059-2:2015 Page 2 of 19 pages Foreword SMPTE (the Society of Motion Picture and Television Enginee
5、rs) 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 Documents, including Standards, Recommended Practices, and Engineering Guidelines, are
6、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 ISO, IEC and ITU. SMPTE Engineering Documents are drafted in accordance with the rules
7、 given in its Standards Operations Manual. SMPTE ST 2059-2 was prepared by Technology Committee 32NF. Intellectual Property SMPTE draws attention to the fact that it is claimed that compliance with this Standard may involve the use of one or more patents or other intellectual property rights (collec
8、tively, “IPR“). The Society takes no position concerning the evidence, validity, or scope of this IPR. Each holder of claimed IPR has assured the Society that it is willing to License all IPR it owns, and any third party IPR it has the right to sublicense, that is essential to the implementation of
9、this Standard to those (Members and non-Members alike) desiring to implement this Standard under reasonable terms and conditions, demonstrably free of discrimination. Each holder of claimed IPR has filed a statement to such effect with SMPTE. Information may be obtained from the Director, Standards
10、formulae which specify the ongoing alignment of signals to time since the SMPTE Epoch; and formulae which specify the calculation of SMPTE ST 12-1 time address values and SMPTE ST 309 date values. A basic understanding of these concepts that are described in SMPTE ST 2059-1 will be helpful to reader
11、s of ST 2059-2. Synchronization is considered to have been achieved when network-based time accuracy between any two slave devices with respect to the master reference is within 1 microsecond. This standard is capable of providing a higher degree of accuracy depending on the network architecture. Th
12、is profile is designed with the following purposes in mind: To permit a slave to be synchronized within 5 seconds of its connection to the operational PTP network. While there are many factors that will in practice influence the synchronization time, the default values of configurable attributes hav
13、e been chosen to help achieve this target. Having achieved initial synchronization, to maintain network-based time accuracy between any two slave devices with respect to the master reference within 1 microsecond. To convey Synchronization Metadata (SM) required for synchronization and time labeling
14、of audio/video signals. SMPTE ST 2059-2:2015 Page 4 of 19 pages 1 Scope This standard specifies a Precision Time Protocol profile specifically for the synchronization of audio/video equipment in a professional broadcast environment. The profile is based on IEEE Std 1588-2008 and includes a self-cont
15、ained description of parameters, their default values, and permitted ranges. 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 potenti
16、ally helpful to the user, but not 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 lab
17、eled 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 the document and from which no deviation is permitted. The keywords, “should“ and “should not“ indicate that, among several
18、 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; or that (in the negative form) a certain possibility or course of action is deprecated but not prohibited. The keywords “
19、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 not be used, and may be defined in the future. The keyword “forbidden” indicates “reserved” and in addition indicates tha
20、t 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 implemented, all recommended provisions (“should“) as described. A conformant implementation need not implement optional provisi
21、ons (“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 follows: Normative prose shall be the authoritative definition; Tables shall be next; followed by formal languages; then figure
22、s; and then any other language forms. 3 Normative References The following standards contain provisions that, 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 a
23、greements based on this standard are encouraged to investigate the possibility of applying the most recent edition of the standards indicated below. IEEE Std 1588-2008, IEEE Standard for a Precision Clock Synchronization Protocol for Networked Measurement and Control Systems1 IETF RFC 2236, Internet
24、 Group Management Protocol , Version 2 (IGMPv2) 1 IEEE-1588 is a registered trademark of the Institute of Electrical and Electronics Engineers, Inc. SMPTE ST 2059-2:2015 Page 5 of 19 pages IETF RFC 2710, Multicast Listener Discovery (MLD) for IPv6 IETF RFC 3376, Internet Group Management Protocol, V
25、ersion 3 (IGMPv3) IETF RFC 3810, Multicast Listener Discovery Version 2 (MLDv2) for IPv6 4 Definition of Terms and Acronyms 4.1 Big-endian Also known as network order, a byte order where the bytes of a word are transmitted such that the most significant Byte is transmitted first. 4.2 Byte An ordered
26、 sequence of 8-bits, also termed an octet. 4.3 Daily Jam An optional daily procedure carried out within a facility that uses SMPTE ST 12-1 time code in which the time address value is adjusted to correspond to Local Time at the chosen time of the Daily Jam. It is usually carried out in the early hou
27、rs of the morning at a non-sensitive time as determined by the operator of the facility. Note: The term “Daily Jam“ is historical and used in that context. This standard does not constrain the jam to take place on a daily basis. In some systems it could occur only as required to accommodate disconti
28、nuities such as Leap Seconds or daylight saving time adjustment. 4.4 Grandmaster clock Within a PTP domain, a clock that is the ultimate source of time for clock synchronization using the Precision Time Protocol as defined in IEEE Std 1588-2008. 4.5 Link A network segment between two Precision Time
29、Protocol (PTP) ports supporting the peer delay mechanism of the IEEE Std 1588-2008. 4.6 Local Time The time (and date) as chosen by the facilitys system administrator and implemented by the system. This is typically the calendar date and time-of-day in common use in the locality. It usually includes
30、 an offset from UTC indicating the time zone, accumulated Leap Seconds by the rules of UTC, and, where observed, daylight saving time (summer time) by the rules of the responsible authority. 4.7 Master clock In the context of a single Precision Time Protocol (PTP) communication path, a clock that is
31、 the source of time to which all other clocks on that path synchronize. 4.8 Octet A sequence of 8 bits, also known as a byte. 4.9 PTP Precision Time Protocol as defined in IEEE Std 1588-2008. SMPTE ST 2059-2:2015 Page 6 of 19 pages 4.10 PTP Domain A logical grouping of clocks that synchronize to eac
32、h other using the Precision Time Protocol, but that are not necessarily synchronized to clocks in another domain. See also IEEE Std 1588-2008, Subclause 7.1. 4.11 PTP epoch The origin of the timescale of a domain as defined in IEEE Std 1588-2008 (see Subclause 7.2.2). 4.12 PTP time The time elapsed
33、since the PTP epoch as conveyed by the Precision Time Protocol as defined in IEEE Std 1588-2008 (see Subclause 7.2). Note: The PTP epoch as defined above is 63072010 seconds before 1972-01-01T00:00:00Z (UTC). Note: This PTP epoch is the same as the SMPTE epoch as defined in SMPTE ST 2059-1. 4.13 Sla
34、ve clock In the context of a single Precision Time Protocol (PTP) communication path, a clock that may synchronize to another clock. 4.14 SM: Synchronization Metadata Metadata required for the synchronization of audio/video signals. 4.15 Synchronization signal A reference signal used for the synchro
35、nization of audio/video equipment in a professional broadcast environment, for which a phase relationship with respect to the SMPTE Epoch has been defined (see SMPTE ST 2059-1). 4.16 Time Jump A discontinuity in local time that is known in advance, caused typically by an adjustment to the number of
36、accumulated leap seconds or a change in daylight saving time. 5 PTP Profile 5.1 Profile Identification The PTP Profile shall be identified as follows: PTP Profile: SMPTE profile for synchronization in a professional broadcast environment Version 1.0 Profile identifier: 68-97-E8-00-01-00 This profile
37、 is specified by Society of Motion Picture and Television Engineers (SMPTE) A copy may be obtained from www.smpte.org 5.2 Best Master Clock Algorithm (BMCA) The default best master clock algorithm (BMCA) defined in IEEE Std 1588-2008 (Subclauses 9.3.2, 9.3.3, 9.3.4) shall be used. SMPTE ST 2059-2:20
38、15 Page 7 of 19 pages 5.3 Management Mechanism Management messages are used to access attributes and to generate certain events defined in this standard, and for sending the SM dataset. The management mechanism specified in Subclause 15.2 PTP management mechanism of IEEE Std 1588-2008 shall be used.
39、 5.4 Path Delay Measurement Mechanism The delay request-response mechanism shall be the default path delay measurement mechanism. The peer delay mechanism may also be implemented. Note: A boundary clock with ports supporting each of the two mechanisms could be used to bridge between the different me
40、chanisms. As per IEEE Std 1588-2008, for each master-slave connection only a single mechanism is permitted. 5.5 PTP Attribute Values Attributes not specified by this profile shall use the default initialization values and ranges specified in IEEE Std 1588-2008. The following attributes are specified
41、 by this profile: 5.5.1 Configurable data set members defaultDS.priority1 Default value: 128 Configurable range: 0 to 255 defaultDS.priority2 Default value: 128 Configurable range: 0 to 255 defaultDS.priority1 specifies the priority to be used in the execution of the BMCA. defaultDS.priority2 specif
42、ies the secondary priority to be used in the execution of the BMCA. The above default initialization values are the same as those specified in the Default PTP profiles in Annex J.3 and Annex J.4 of IEEE Std 1588-2008. defaultDS.domainNumber Default value: 127 Configurable range: 0 to 127 A domain co
43、nsists of one or more PTP devices communicating with each other as defined by the protocol. The domain is identified by an integer, the domainNumber, in the configurable range of 0 to 127. defaultDS.slaveOnly Ordinary clocks not capable of or not intended to enter the master state: TRUE Otherwise: F
44、ALSE Note: Slave-only devices are expected to be common in typical system configurations using this profile. SMPTE ST 2059-2:2015 Page 8 of 19 pages portDS.logAnnounceInterval: Default value: -2 Configurable range: -3 to +1 The portDS.logAnnounceInterval specifies the mean time interval between succ
45、essive Announce messages, i.e., the announceInterval. This interval in concert with announceReceiptTimeout governs how quickly the BMCA re-configures the system in the event of a master failure. The portDS.logAnnounceInterval shall be chosen to be uniform throughout a domain. Note: The value of the
46、parameter is the logarithm to base 2 of the time interval in seconds. (For example, an interval of 0.25 s gives a value of -2, and an interval of 2 s gives a value of +1.) In order to facilitate the 5-second synchronization time requirement, the default value, or a shorter interval than the default,
47、 is recommended. portDS.announceReceiptTimeout: Default value: 3 Configurable range: 2 to 10 The value of portDS.announceReceiptTimeout specifies the number of announceIntervals that have to pass without receipt of an Announce message before the occurrence of the event ANNOUNCE_RECEIPT_TIMEOUT_EXPIR
48、ES. The above default initialization value and configurable range is as specified in the Delay Request-Response Default PTP profile in Annex J.3 of IEEE Std 1588-2008. portDS.logSyncInterval: Default value: -3 Configurable range: -7 to -1 The portDS.logSyncInterval specifies the mean time interval b
49、etween successive Sync messages. The value of the parameter is the logarithm to base 2 of the time interval in seconds. This interval is set to a low value (i.e. high message rate) to allow the slaves to synchronize quickly. In order to facilitate the 5-second synchronization time requirement, the default value, or a shorter interval than the default, is recommended. portDS.delayMechanism: Delay request-response: 01h Peer delay: 02h The portDS.delayMechanism specifies the propagation delay measuring option used b
