ANSI SCTE 27 pdf free download
ANSI SCTE 27 pdf free download.Subtitling Methods for Broadcast Cable.
2.1 Terms, Acronyms and Abbreviations
2.1.1 Terms
The following terms are used throughout this document:
message: A sequence of bytes comprising a data structure defined in this Standard. All messages begin with the table_ID and end with the CRC_32 field. Messages are carried in non-PES streams; their starting points within a packet payload is indicated by the pointer_field mechanism defined in the ISO/JEC 13818-I Systems document.
section: A message comprising a portion of an JSO/JEC 13818-1-defined table, such as the Program Association Table (PAT). Conditional Access Table (CAT), or Program Map Table (PMT). The term conforms to MPEG terminology, but since it applies primarily to the delivery of table structures, the more appropriate term “message” is used to refer to non-table oriented data structures such as, for example, the subtitle message.
program element: A generic term for one of the elementary streams or other data streams that may be included in a program.
program: A collection of program elements. Program elements may be elementary streams. Program elements need not have any defined time base; those that do have a common time base and are intended for synchronized presentation. The term “program” is also used in the context of a “television program” such as a scheduled daily news broadcast. The distinction between the two usages should he understood by context.
service: ISO/fEC 13818-I uses the term “program” to refer to a collection of program elements without regard to time. In this Standard, the term “service” is used in this same context to denote a collection of elementary components. Usage of the term service clarifies certain discussions which also involve the notion of the term program in its traditional meaning (in, for example, the statement “A video service carries a series of programs”).
stream: An ordered series of bytes. The usual context for the term “stream” involves specification of a particular PID (such as the “Program Map PID stream”), in which case the term indicates a series of bytes extracted from the packet multiplex from packets with the indicated PID value.
2.2 Stream Type for Subtitling Messages
Stream type ()x82 shall be used for program subtitles defined in this Standard.
2.3 Section and Data Structure Syntax Notation
This document contains symbolic references to syntactic elements. These references are typographically distinguished by the use of a different font (e.g., restricted), may contain the underscore character (e.g., sequence_end_code) and may consist of character strings that are not English words (e.g., dynrng).
The formats of sections and data structures in this document are described using a C-like notational method employed in 1SO/JEC 13818-I. An extension to this method is described below.
Each data structure is described in a table format wherein the size in bits of each variable within that section is listed in a column labeled “Bits.” The column adjacent to the bits column is labeled “Bytes” and indicates the size of the item in bytes. For convenience, several bits within a particular byte or multi-byte variable may be aggregated for the count.ANSI SCTE 27 pdf download.
