1、 Copyright 2008 by THE SOCIETY OF MOTION PICTURE AND TELEVISION ENGINEERS 3 Barker Avenue, White Plains, NY 10601 (914) 761-1100 Approved September 23, 2008 Table of Contents Page Foreword . 2 Intellectual Porperty 2 Introduction . 3 1 Scope . 3 2 Conformance Notation . 3 3 Normative References . 3
2、4 Definitions 4 4.1 Byte 4 4.2 Inserter . 4 4.3 Injector . 4 5 Format of VANC Data Packets 4 5.1 UDW Format 4 5.2 Payload Descriptor Format 5 5.2.1 Mapping syntax version flags 6 5.2.2 Continued packet and following packet flags 6 5.2.3 Duplicate message flag. 6 5.3 ANSI/SCTE 104 Message Format. 7 5
3、.3.1 Serial data connection 7 5.3.2 TCP/IP data connection 7 5.3.3 Maximum ANSI/SCTE 104 message size (Informative) 7 5.4 ANSI/SCTE 104 Messages Exceeding Single Packet Capacity . 7 6 Location of the Vertical Ancillary Data . 7 Annex A Bibliography (Informative) 9 Annex B Comments on the Preferred L
4、ocation of VANC Packets (Informative). 10 Annex C Parsing Messages Conveyed via Serial Data Connections (Informative) 11 Page 1 of 11 pages SMPTE 2010-2008Revision of RP 2010-2007 SMPTE STANDARD Vertical Ancillary Data Mapping of ANSI/SCTE 104 Messages SMPTE 2010-2008 Page 2 of 11 pages Foreword SMP
5、TE (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 Documents, including Standards,
6、 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 ISO, IEC and ITU. SMPTE Enginee
7、ring Documents are drafted in accordance with the rules given in Part XIII of its Administrative Practices. This SMPTE Engineering Document was prepared by Technology Committee D27. Intellectual Property At the time of publication no notice had been received by SMPTE claiming patent rights essential
8、 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. Introduction This section is entirely informative
9、 and does not form an integral part of this Engineering Document. This Standard serves in conjunction with ongoing work under SMPTE S22 defining communications mechanisms between program originators Traffic and Billing systems and their facility Automation Systems. One facet of the end-to-end progra
10、m system is Automation System triggering of downstream Digital Program Insertion (“DPI”). Such insertion is triggered typically by the presence of ANSI/SCTE 35 messages in the MPEG-2 Transport Stream. ANSI/SCTE 104 defines the Communications API between the Automation System and the associated Compr
11、ession System that results in the insertion of those ANSI/SCTE 35 messages. ANSI/SCTE 104 was drafted with bidirectional TCP/IP data communications in mind, but made explicit provision for unidirectional carriage of messages in video signals. SMPTE 2010-2008 Page 3 of 11 pages 1 Scope This Standard
12、specifies a mechanism for the mapping of ANSI/SCTE 104 messages (with a maximum size of 2000 bytes) into 10-bit vertical ancillary data space. It is equally applicable to standard definition digital systems as well as high definition digital systems. 2 Conformance Notation Normative text is text tha
13、t 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 indispensable, and can be removed, changed, or added editorially without affecting interoper
14、ability. 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 individual paragraphs that start with “Note:” The keywords “shall“ and “shall not“ indicate requireme
15、nts 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 recommended as particularly suitable, without mentioning or excluding others; or that a certain course
16、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 courses of action permissible within the limits of the document. The keyword “reserved” indicates
17、 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 defined in the future. Unless otherwise specified the order of precedence of the types of normat
18、ive information in this document shall be as follows. 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 The following standards contain provisions which, through reference
19、 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 applying the most rec
20、ent edition of the standards indicated below. ANSI/SCTE 35-2004, Digital Program Insertion Cueing Message for Cable ANSI/SCTE 104-2004, Automation System to Compression System Communications Applications Program Interface (API) SMPTE 291M-2006, Television Ancillary Data Packet and Space Formatting S
21、MPTE RP 168-2002, Definition of Vertical Interval Switching Point for Synchronous Video Switching SMPTE 2010-2008 Page 4 of 11 pages 4 Definitions 4.1 Byte Throughout this Standard, the term byte shall refer to 8-bit values (and not 10-bit values) unless otherwise stated. In this Standard, 10-bit va
22、lues are called “words.” 4.2 Inserter An Inserter is a device that places an ANSI/SCTE 104 message into the VANC space of a digital video data stream in response to receipt of that message via TCP/IP or serial data communications. 4.3 Injector An Injector is a device (or combination of devices) that
23、 convert ANSI/SCTE 104 message data into an SCTE 35 splice_info_section() placed in an MPEG-2 TS. In the context of this document the Injector expects to receive the ANSI/SCTE 104 message data in VANC. 5 Format of VANC Data Packets Each data packet shall comply with the format defined in SMPTE 291M
24、for a 10-bit type 2 ancillary space (ANC) packet. It consists of the ancillary data flag (ADF), the data ID (DID), the secondary data ID (SDID), the data count (DC), the user data words (UDW), and the checksum (CS). The UDW consists of the data payload. The DID word shall be set to the value 41h. Th
25、e SDID word shall be set to the value of 07h. The same values of DID/SDID shall be used for all duplicated or continued packets (see 5.2.2 and 5.2.3). DC is a count of the number of words in the UDW. Each ANSI/SCTE 104 message shall begin a new VANC data packet. If an ANSI/SCTE 104 message exceeds t
26、he capacity of a single VANC packet, multiple data packets will be required. No more than one complete ANSI/SCTE 104 message may be transmitted per video frame time. An ANSI/SCTE 104 message utilizing this specification shall be limited to a maximum of 200 bytes in length for a single_operation_mess
27、age() structure or a maximum of 2000 bytes in length for a multiple_operation_message() structure. NOTE Additional guidance on message length is provided by Informative 5.3.3. 5.1 UDW Format The UDW of each ANSI/SCTE 104 message starts with a one byte Payload Descriptor, followed by one or more byte
28、s from the variable length ANSI/SCTE 104 message itself as shown in Figure 1. The format of the ANSI/SCTE 104 message bytes is defined in 7 (“Message Formats”) of ANSI/SCTE 104. The ANSI/SCTE 104 single_operation_message() or a multiple_operation_message() structure (as the case may be) shall first
29、be extracted from whatever outer message structure may have been used to transport it to the Inserter before being placed in VANC. The ANC packet UDW shall be a sequence of 10-bit words. The ANSI/SCTE 104 message information is transmitted in bits b7 through b0 of the 10-bit data word. Bit b8 is eve
30、n parity for bits b7 through b0 of the 10-bit data word, and bit b9 equals not bit b8. SMPTE 2010-2008 Page 5 of 11 pages Figure 1 VANC packet overall structure The Payload Descriptor shall be added by the Inserter per 5.2. Other single or double-byte values from either an ANSI/SCTE 104 single_opera
31、tion_message() or a multiple_operation_message() shall be placed into the UDW words following the Payload Descriptor. NOTE These values should be according to Table 7-3 of ANSI/SCTE 104 for a single_operation_message()or FFFFh for a multiple_operation_message(). 5.2 Payload Descriptor Format The Pay
32、load Descriptor is a one byte value, added by the Inserter, that shall be the first word of the UDW. Table 1 summarizes the function of each bit of the Payload Descriptor byte. Table 1 Payload Descriptor Bit Assignments Bit Position Name Description 7 (MSB) Reserved Shall set to 0 6 Reserved Shall s
33、et to 0 5 Reserved Shall set to 0 4 VERSION (MSB) 3 VERSION (LSB) Two bit value used to indicate syntax revision for mapping scheme shall be set to “01” 2 CONTINUED_PKT Set to “1” when the ANSI/SCTE 104 message payload carried continues in the next VANC packet (see 5.2.2). 1 FOLLOWING_PKT Set to “1”
34、 when this packet is a continuation from the prior VANC packet in a video frame (see 5.2.2). 0 (LSB) DUPLICATE_MSG Set to “1” when this message duplicates the message of a previous video frame A Payload Descriptor byte value of 08h (0000 1000b) indicates the payload is carried in a single VANC data
35、packet. Other values indicate other possible combinations. CSHeader Type 2 Header SCTE 104 MessageUDW6 bytes Payload Descriptor SMPTE 2010-2008 Page 6 of 11 pages 5.2.1 Mapping syntax version flags Two bits in the descriptor byte are used to signal the mapping syntax version to decoding devices. Bit
36、 4 shall be set to logical zero and bit 3 shall be set to logical one for the mapping syntax described in this Standard. Table 2 Encoding Version (Bits 3 and 4) Bit 4 Bit 3 Reserved 0 0 Version 1 Mapping (current) 0 1 Reserved for future use 1 0 Reserved for future use 1 1 5.2.2 Continued packet and
37、 following packet flags ANSI/SCTE 104 messages longer than 254 bytes must be encoded in two or more consecutive VANC packets (see 5.4). These packets should be inserted on the same line of the video or continued on the line following. The “Continued_Pkt” flag (bit 2 of the payload descriptor byte) i
38、n all but the last VANC packets shall be set to logical one to signal that the ANSI/SCTE 104 message is split across two or more packets. The “Following_pkt” flag (bit 1 of the payload descriptor byte) in the packet containing the first part of the ANSI/SCTE 104 message shall be set to logical zero.
39、 The “Following_pkt” flag in the packet(s) containing the remaining parts of the ANSI/SCTE 104 message shall be set to logical one. Table 3 Continued Packet and Following Packet Flag Bits (Bits 1 and 2) CONTINUED_PKT Bit 2 FOLLOWING_PKT Bit 1 ANSI/SCTE 104 messages are contained within a single pack
40、et 0 0 First packet 1 0 Intermediate packets 1 1 ANSI/SCTE 104 messages are contained within two or more packets Final packet 0 1 5.2.3 Duplicate message flag Certain ANSI/SCTE 104 messages are permitted to be repeated multiple times in different frames of video to ensure receipt (See 8.3 in ANSI/SC
41、TE 104). This may be accomplished either by the Automation System or by the Inserter. Should the inserter provide this function, it must retain the message contents in a buffer, and it shall set the Duplicate_Msg flag bit to logical one in each and every duplicated message. A message may not be dupl
42、icated within the same frame of video. Duplicated messages need not be placed in immediately succeeding frames, rather may be spaced apart by several frames. Note: If this approach is taken, then certain values within certain SCTE 104 messages (such as pre-roll times) may need to be adjusted to main
43、tain frame accuracy. NOTE Receiving equipment may use packets with the Duplicate_Msg flag bit set to logical one to assist downstream equipment with recovery from interruptions in the video stream. SMPTE 2010-2008 Page 7 of 11 pages 5.3 ANSI/SCTE 104 Message Format 5.3.1 Serial data connection If th
44、e VANC Inserter utilizes a serial data connection to the Automation System, then the messages received, which should have been encoded with the syntax specified in B.1 (“The Basic Link Layer Syntax”) of ANSI/SCTE 104, shall be decoded into the normal ANSI/SCTE 104 message format specified above. Thi
45、s entails removal of any ESC sequences in the message prior to placement in the VANC payload. 5.3.2 TCP/IP data connection If the VANC Inserter utilizes a TCP/IP data connection to the Automation System then the message bytes as received (after removal of any TCP/IP wrapper data) shall be placed int
46、act into the VANC UDWs (see 5.1). 5.3.3 Maximum ANSI/SCTE 104 message size (Informative) ANSI/SCTE 104 messages using the single_operation_message() structure cannot exceed 200 bytes in length due to constraints in the message syntax, and typically range is between 13 and 21 bytes in length. ANSI/SC
47、TE 104 messages using the multiple_operation_message() structure might, under certain circumstances, exceed 254 bytes in length, although a typical message length is less than 100 bytes. The normative constraints on message size may be found in the final paragraph of 5. Should the Automation System
48、wish to send a number of time deferred requests at once (which would result in a single very large multiple_operation_message() structure), that it might instead divide these into several multiple_operation_message() structures which have the same trigger point value specified. Inserter manufacturer
49、s should be encouraged to document the maximum message length handled by a given device. 5.4 ANSI/SCTE 104 Messages Exceeding Single Packet Capacity As noted in 5, an ANSI/SCTE 104 single_operation_message() structure shall not exceed 200 bytes and is thus limited to a single ANC packet. Should an ANSI/SCTE 104 multiple_operation_message() structure exceed 254 bytes in length, it shall be divided into two or more smaller ANC packets by breaki
